Protecting self from unknowingly posting copyrighted material

Question: Someone is getting me to make them a Facebook page. They are giving me the material. They also want me to edit (Photoshop) some images for them. I'm worried that I may be breaking copyright. If I get them to sign a contract agreeing that all material they provide me, they own the copyright for, and they agree to indemnify me, are these two things enough to protect me if someone makes a claim that I posted copyrighted material?
Answer: Copyright Primer
If you make a copy (or a derivative work like a Photoshopped photo) of a copyrighted work without the commercial copyright owner's permission then you are prima facie guilty of copyright infringement. Further, if you do not give attribution to or deal in a derogatory way with the holder of any moral copyright, you are breaching their rights as well. The commercial and moral copyright holder(s) may or may not be the same people.
If you are alleged to have infringed copyright you may be able to avail yourself of a fair dealing/use defense, however, in the circumstances you describe this is unlikely to be successful. Basically, what you are describing is not fair dealing/use.
It is unlikely that what you are proposing would be considered criminal infringement so you would not be subject to criminal sanctions like gaol time or fines.
You are open to being sued by the copyright (commercial and/or moral) holder. If you can prove innocent infringement (i.e. that you made all reasonable efforts to determine who the copyright holders are and sought their permission) then your damages are limited to an accounting of profits (i.e. you have to pay them the profit you made by breaching their copyright).
In the contract with your client you can require them to provide you with an indemnity against defense costs and damages: this means you can sue them if you get sued. Of course, if they have no money this doesn't really help. You can also take out insurance against this, however, their liability will be excluded if you breach the terms of your insurance contract.
What you need to do

Find the copyright owner. For photos, the commercial copyright holder is usually the photographer or the photographer's employer: it is not the subject of the photograph! For text, the commercial copyright holder is usually the author or their employer. The moral copyright is usually held by the photographer/author unless they have assigned their right to someone else.
Get and document their permission and publish in accordance with the permission given (including attribution etc.).
If you cannot determine the copyright owner, you may be able to determine if the works are public domain. In general, anything created before the 20th century is public domain: things more recent than that are harder to be definitive about. Some author's such as the US government (but most other governments do claim copyright) specifically renounce copyright - all their works are public domain.
If you do inadvertently breach copyright, comply immediately with any request to stop.
Comment: What if the person supplying the photos lies and says they're the owner?


What does "sales play" mean?

Question: I've seen the phrase "sales play" on IBM site (see link).
What does it mean?
Answer: A play in this context is a plan or strategy -- in this case, a plan or strategy for making a sales pitch. Note that one of the links on the page in your link is for a sales playbook, which contains this preface:

This playbook is designed to provide you a view of the IBM Business Partner sales plays that your sellers can use as they develop their
  sales strategy
Each play includes quick reference guides and enablement links to pursue sales activities throughout the sales cycle
Answer: I think Gnawme nailed it.  In American football, each team has a playbook, which is comprised of running plays, and passing plays.  Before each play, each team gets in a huddle, and calls a play.  The idiom "take a play from the playbook" is sports-derived; it essentially means "select an apt plan or strategy."
I'm guessing that, by using the term sales play, the company is training its sales force to "take a play from the playbook" in various situations.  Moreover, by using this somewhat playful means of compiling and listing these approaches, IBM is trying to emphasize the concept of teamwork among its sales force.

What does "sales play" mean?


Is it safe to leave the Joomla setting "Preview Module Positions" enabled?

Question: Using at least Joomla 2.5 and 3.1. Under the template manager options the setting "Preview Module Positions" must be set to "enabled" for previews to work. My question is, why isn't this feature always on? Is it a security risk to have it enabled on a live site? Does it slow the site down? Since the template manager is an administrator component, I wouldn't think it would be a problem, but I can't see any other reason to offer this option. Thanks!
Answer: The reason is to avoid 'information disclosure'. If that feature is enabled, it is pretty easy to identify the site being a Joomla! site. It does not have any other negative impact on your site.
Comment: Can you tell what actually is disclosed? Or share a link to such docs?
Comment: It reveals that you're running Joomla!. It reveals the logical structure of your template. Both information can be used as (part of) an attack vector.
Answer: There is no need to enable this module after you have launched your site.
This option is used while we are developing the site,
Its helps the developers to identify which position the module takes.
something like debug mode enable options,  some templates will give some border around the module position too.
so my concern is after launch the site there is no need to enable that settings..
Hope it make sense..


Is the commandment 'You shall not murder' the most important commandment in Judaism?

Question: Does the rule  'You shall not murder'  stand above all other rules in Judaism?
Comment: How could one evaluate that? What do you mean by "most important" or "stand above"? (Note that 'murder' here has technical definitions. It doesn't just mean cause someone to die, as Jews are commanded to execute certain criminals and to go to war under certain circumstances.)
Comment: I think that this is a fair question, and that "There is no concept of 'most important commandment' in Judaism" is a fair answer. The question could be improved significantly with the addition of why one might suspect that this commandment might have this status, and some clarification of what "most important" may mean, in this context.
Comment: Maybe that other person is really good at guessing what you mean, or maybe he was trying to get you to stop asking, or maybe he was just a fool. The fact is I don't know how anyone can intentionally answer the current question accurately.
Comment: ... Unfortunately, it is difficult to provide a clear answer to your question, because `"the most important commandment"` and `"stand above all other rules"` could be interpreted in various ways. By some metric, for example, you could say that Torah study is the most important commandment ([*Pe'ah* 1:1](https://he.wikisource.org/wiki/%D7%9E%D7%A9%D7%A0%D7%94_%D7%A4%D7%90%D7%94_%D7%90_%D7%90)). By another metric, you could say that avoiding slander is the most important commandment (Rambam, *Hil. Dei'os* 7:4). Or charity (*Shabbos* 139a).
Comment: @Fred http://www.rationalistjudaism.com/2013/09/kneged-kulam.html : "There are several mitzvos about which Chazal say that they are equal to all other mitzvos together. These are the mitzvah of living in Eretz Yisrael, Shabbos, Bris Milah, Tzitzis, and Gemilas Chasadim."
Comment: well I asked someone from another religion the same question about his religion and he just answered: yes, it is.
Comment: See [DoubleAA's answer here](http://judaism.stackexchange.com/a/14682) regarding the extreme severity of murder in Judaism. See especially the quotes from the Rambam there, which suggest that `'You shall not murder'` is the most important commandment in Judaism in a certain sense.
Comment: http://beinenu.com/sites/default/files/alonim/90_29_30_73.pdf
Answer: Judaism does not specify the importance or reward of different commandments. We observe them all because God says so without trying to rationalize (although many have proposed explanations for the various commandments, e.g., Sefer Hachinuch).
It is however true that breaching different commandments created the need (in Temple times) for different sacrifices.
The Rambam in Mishne Torah Hilkhot Sanhedrin ch 15 lists the punition for various aveirot (sins). In his view, unlawful premeditated murder calls for death penalty but of a level below than other aveirot, e.g., some forbidden relations, idol worship, violating the Shabbat. But as is well explained elsewhere on MY one cannot use this classification to judge which mitzva (commandment) is more important.
In a positive way, there is a widely known story in the Talmud (Shabbat 31a) of the great sage Hillel, quoted from here

A gentile wanted to convert to Judaism. This happened not
  infrequently, and this individual stated that he would accept Judaism
  only if a rabbi would teach him the entire Torah while he, the
  prospective convert, stood on one foot. First he went to Shammai, who,
  insulted by this ridiculous request, threw him out of the house. The
  man did not give up and went to Hillel. This gentle sage accepted the
  challenge, and said:
"What is hateful to you, do not do to your neighbor. That is the whole
  Torah; the rest is the explanation of this -- go and study it!"

Does it mean loving your neighbor is the most important commandment? No but it is a starting point for all the rest.
Comment: @JMFB priorities and importance are different things. I didn't discuss priorities. Now on your specific points. One doesn't do a Brit on Shabbat for a non-natural (eg Cesarean) delivery. What does this tell us about the relative importance of a Brit vs Shabbat? Nothing. It tells us that in some cases we do a Brit on Shabbat, in other cases not. On rewards there are only two mitzvot in the Torah promising long life as a reward. Shiluach haken (your example) and kibud av v'eim (respecting your parents). Just two. Does it mean the other mitzvot are not important? Of course not.  B'shalom.
Comment: This answer is 100% incorrect. We have lots of measures for what commandments take priorities over other commandments. You have to do a bris on shabbos. The gemara even speaks about beautifying the mitzvah of bris after it's completed. So bris takes priority. It absolutely specifies rewards for commandments. If you shoo a mother bird from a tree before taking the eggs you get long life. That's a specific reward. I could give enough examples of how this answer is wrong I could fill up 100 of these comment boxes. -1
Comment: @JMFB this question doesn't ask about relative priorities. Those are much more well-defined than relative importance.
Comment: @JMFB If you can fill 100 comment boxes, please just give me 10 examples of Mitzvot whose reward is specified.
Answer: Does the rule 'You shall not murder' stand above all other rules in Judaism?
NO (but it's up there)
to summarize the quotes below (in order),
if we consider To know that there is a God a commandment as the Rambam does, it seems to be the most important commandment in Judaism.
Regarding our connection to G-d: their are is no difference in commandments
Regarding the way the Torah speaks about it: murder is on top
Regarding punishment for not keeping a commandment:
1. only a murderer is "killed" even if the witnesses did not observe his act together, or a warning was not given; or the witnesses to a murder contradicted each other with regard to the fine points of the testimony, but not with regard to the fundamental questions.
2. but if the testimony is perfect then the punishment for murder is not the most severe
Regarding being considered as a gentile regarding the whole Torah except marriage: murder is not one of the commandments if transgressed make him as a gentile
Regarding getting killed and not transgressing: murder is one of the 3 that even in privet you should get killed and not do it

Mishneh Torah » Sefer Madda » Yesodei haTorah - Chapter One
Halacha 1

The foundation of all foundations and the pillar of wisdom is to know that there is a Primary Being who brought into being all existence. All the beings of the heavens, the earth, and what is between them came into existence only from the truth of His being.

see footnote 2 here

the Tanya in chaper 24

...
  It is thus clear that he who sins and transgresses against G‑d's Will even in a minor offense, is, at the time he commits it, completely removed from the Divine Holiness, meaning G‑d's unity and oneness,
  ...
  but they (laws regarding the sins) are simply a matter of Scriptural decree.
  (The sinner, however, who does distinguish between the gravity of the various transgressions, sacrificing his life for the prohibition of idolatry but not even restraining his desire for others, surely has his thinking clouded by the "spirit of folly" of the kelipah, which obscures his hidden love of G‑d. For in reality, every transgression creates the ultimate separation between the sinner and G‑d.)

Rambam Mishneh Torah » Sefer Nezikim » Rotzeach uShmirat Nefesh
Rotzeach uShmirat Nefesh - Chapter One
Halacha 4

...
  There is nothing that the Torah warned so strongly against as murder, as Ibid.:33 states: "Do not pollute the land in which you live, for blood will pollute the land."

Mishneh Torah» Sefer Nezikim » Rotzeach uShmirat Nefesh - Chapter Four
Halacha 8

The following laws apply when a person kills people, but the witnesses did not observe his act together - instead one saw him after the other did: a person killed in the presence of witnesses, but a warning was not given; or the witnesses to a murder contradicted each other with regard to the fine points of the testimony, but not with regard to the fundamental questions.
  All those murderers should be forced to enter a kipah.**There they are fed parched bread and small amounts of water until their digestive tract contracts. Then they are fed barley **until their bellies burst because of the extent of the sickness and they die.

Halacha 9

This measure is not taken with regard to other crimes punishable by execution by the court. If a defendant is liable for execution, he should be executed. If he is not liable for execution, he should be released.
Although there are other sins that are more serious than murder, they do not present as serious a danger to society as murder does. Even idol worship - and needless to say, incest or the violation of the Sabbath - are not considered as severe as murder. For these sins involve man's relationship with God, while murder also involves man's relationship with his fellow man.
Whoever commits this sin is an utterly wicked person. All the mitzvot that he performs throughout his lifetime cannot outweigh this sin and save him from judgment. Thus, Proverbs 28:17 states: "A man weighed down with life's blood will flee to the pit."
Come and learn from the example of Ach'av King of Israel. He was an idolater so debased in his paganism that I Kings 21:25 says: "There was none like Ach'av who gave himself over to the performance of wickedness in the eyes of God." And yet when his merits and sins were weighed in the presence of the Lord of spirits, there was no sin that warranted his destruction and was not counterbalanced by a positive quality, except the blood of Navot.
Thus, it is written Ibid. 22:21, in the description of the prophecy of Ach'av's death in battle: "And the spirit came and stood before God." Our Sages commented:: "This is the spirit of Navot." And God told the spirit (Ibid.:2): "You will persuade him and prevail."
Now this wicked man Ach'av did not actually kill his victim with his own hands; he merely brought about his death. How much more so this condemnation should apply when a person kills another with his own hands.

and as the @mbloch answer brought
Mishneh Torah » Sefer Shoftim » Sanhedrin veha`Onashin haMesurin lahem- Chapter 14
Halacha 4

Stoning to death is a more severe form of execution than burning. Burning is a more sever form than decapitation, and decapitation is more sever than strangulation...

Mishneh Torah » Sefer Nezikim » Rotzeach uShmirat Nefesh- Chapter One
Halacha 1

Whenever a person kills a human being, he transgresses a negative commandment, as Exodus 20:13 states: "Do not murder." If a person kills a Jew intentionally in the presence of witnesses, he should be executed by decapitation...

and
Mishneh Torah » Sefer Kedushah » Shechitah
Shechitah - Chapter 4
Halacha 14

...
  an apostate because of worship of false deities, one who violates the Sabbath in public, or a heretic who denies the Torah and [the prophecy of] Moses our teacher, as we explained in Hilchot Teshuvah, he is considered as a gentile (regarding the whole torah except marriage see hear and hear ) and [an animal] he slaughters is a nevelah.

but
Mishneh Torah » Sefer Madda » Yesodei haTorah
Yesodei haTorah - Chapter Five
Halacha 1

...
  What is implied? Should a gentile arise and force a Jew to violate one of the Torah's commandments at the pain of death, he should violate the commandment rather than be killed, because [Leviticus 18:5] states concerning the mitzvot: "which a man will perform and live by them." [They were given so that] one may live by them and not die because of them. If a person dies rather than transgress, he is held accountable for his life.

Halacha 2

When does the above apply? With regard to other mitzvot, with the exception of the worship of other gods, forbidden sexual relations, and murder. However, with regard to these three sins, if one is ordered: "Transgress one of them or be killed," one should sacrifice his life rather than transgress.
When does the above apply? When the gentile desires his own personal benefit - for example, he forces a person to build a house or cook food for him on the Sabbath, he rapes a woman, or the like. However, if his intention is solely to have him violate the mitzvot, [the following rules apply:] If he is alone and there are not ten other Jews present, he should transgress and not sacrifice his life. However, if he forces him [to transgress] with the intention that he violate [a mitzvah] in the presence of ten Jews, he should sacrifice his life and not transgress. [This applies] even if [the gentile] intended merely that he violate only one of the [Torah's] mitzvot.
Answer: This is almost impossible to answer without ruffling someone's feathers but here is some food for thought.
Based on the idea that you are making reference to one of the ten statements (עשרת הדברות) and there is a teaching that all the 613 mitzvot are contained and alluded to in the ten statements, (See the commentary Heichal HaBracha of the Komarna Rebbe on the giving of the Torah.) the concept mentioned in the Mechilta on this is worth considering.
There is a question about what the Jewish people actually heard from HaShem directly. The view of Rabbi Yishmael is that they heard the first two statements which include all the others. They responded 'Yes' to the positive commandments and 'No' to the negative commandments. That is because the general categories of positive and negative encompass all the commandments.
But the opinion of Rabbi Akiva is that they heard only the first statement directly, which includes all the others. They answered 'Yes' for the positive commandments and 'Yes' for the negative commandments. Here's a link: http://hebrewbooks.org/pdfpager.aspx?req=40606&st=&pgnum=88
This view of Rabbi Akiva parallels the order set down in creation mentioned in Bereshit. The 10 statements at the giving of the Torah parallel the 10 utterances of the creation of the universe.
Based on the language we say in Lecha Dodi, "Shamor v'zachor b'dibbor echod", (Negative and positive in one statement, G-d caused us to hear.), it seems the view of Rabbi Akiva is accepted.
In this context, the commandment of 'You shall not murder' is a subset of the first commandment and would therefore not be 'the most important'.
Another interesting perspective is found in Sefer Avkat Rochel by Rabbeinu Makir ben Abba Mori, book one, chapter one, which says the Sages say the last of the ten, 'Lo tachmod', is the greatest and all the others are dependent upon it. It goes on to say that one who fulfills 'lo tachmod' is considered to have fulfilled the entire Torah. Here is a link:
http://hebrewbooks.org/pdfpager.aspx?req=42999&st=&pgnum=3
Here again, it is emphasizing the concept of all the others being contained within the one.
In the context of Avkat Rochel, this appears to be emphasizing the kabbalistic concept of 'Ohr Yashar', emanation from above to below and 'Ohr Chozer', the return to the source from below to above. In either case, the point of origin contains all the particulars that follow it.
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](http://chat.stackexchange.com/rooms/34171/discussion-on-answer-by-yaacov-deane-is-the-commandment-you-shall-not-murder-t).
Answer: First unlike an answer above to which I commented under, there is clearly a hierarchy to commandments. I can give many many examples. So it is a valid question, although as someone pointed out in the comments section it's not clear what you mean. Do you mean do you get the most severe punishment for it? Do you get the most credit if you don't do it during your life? Are there other punishments on earth or in shamayim that are worse than for the act of committing murder? Is this simply a moral or ethical question without consideration of punishment or reward? Are you concerned about what happens when there's a situation where there's a conflict between murder and another commandment, Etc. Etc.
Preserving your life, or perhaps not endangering your life, is a fundamental mitzvah. However if someone points a gun at you and tells you to point a gun at someone else and kill them or they will kill you, you can't kill an innocent person in that circumstance to save yourself.
If there's a bris and it falls on shabbos you have to perform the bris on shabbos even if you have to carry the knife on shabbos to do it. In fact you can even beautify the mitzvah(2nd cut) after the first cut is done even though the mitzvah is completed at that time. Gemara Shabbos second chapter.
So we see there is an order, a ranking so to speak, to mitzvahs. We need this to know when two mitzvahs conflict which one do we follow. We also have a hierarchy based on punishment. We also factor in sins against man vs sins against hashem as alluded to in another answer.
This is the only thing I could think of and I'm going to get downvoted for this, because of lack of citation. I'm tempted to make this a community wiki, although I'm hoping somebody else might be so kind as to give me the reference for this.

It does say somewhere that, "embarrassing somebody is worse then
  killing a person because when you kill somebody it kills their body,
  but when you embarrass them it kills their soul." (citation help
  please)

I believe it's in the gemara in the story about the new rosh yeshiva that didn't want the new student to know he lit the furnace in the morning so let his beard catch on fire so as not to embarrass the new student.
Comment: I agree with you that the question is unclear, but do you really think that "embarrassing somebody is worse than killing" is true for any reasonable definition of "worse"? I think it's pretty clear that that _gemara_ is not to be taken literally. It doesn't even fit the "relative priority" standard that your answer talks about. If someone points a gun at you and says "embarrass somebody else" do you think you have to refuse?
Comment: The gemara about "embarassing someone in public is equal to murder" is Baba Metzia 58b at the bottom.
Comment: Link for the English http://halakhah.com/babamezia/babamezia_58.html
Comment: @Daniel +1 also note the gemara really says "equal to murder", but of course it is not meant literally either


Why are computable numbers (in Turing's sense) enumerable?

Question: Why are computable numbers (in Turing's sense) enumerable?
It must be very obvious, but I'm currently just not seeing it.
Comment: Isn't it simply because all TMs are enumerable?
Comment: Being enumerable means (by definition) that there is a Turing machine that halts with a yes-answer for every yes-instance.  Since being computable means there is a Turing machine that halts with the correct answer for every input, it is easy to see that being computable implies it is enumerable (it is a sub case).
Comment: That must be it.
Comment: I don't think this is the meaning of "computable" in this case. It is a construction problem, not a decision problem.
Answer: I'm assuming that your definition of a computable number is this: there is a Turing machine that on input $n$, halts with the $n$th bit of the number.
Suppose there were a recursive enumeration of Turing machines that produce computable numbers. You can use diagonalization to come up with a new computable number which isn't part of this recursive enumeration.
It is tempting to enumerate computable numbers by enumerating Turing machines, but not every Turing machine corresponds to a computable number, and in general deciding whether a Turing machine halts for all inputs (let alone output either 0 or 1) is not computable. It is, however, possible to enumerate all efficient computable numbers, say ones whose running time is polynomial, by using clocked Turing machines.
Comment: So even though the cardinality of a set (in this case, the set of computable numbers) is not bigger then the cardinality of another set that is listable (the set of all TMs), it doesn't mean that the first set can be listed.
Answer: If by enumerable, you mean that there is a bijection with the natural numbers (i.e., countable), then no, computable numbers are not enumerable.
Let's define the problem more precisely: a "Number-Printing Turing Machine (NPTM)" is a Turing Machine that, for every state transition, may print nothing, or may print any decimal digit, the minus sign, or the period. This is enough to print decimal representations of real numbers.
Lets define a computable real number as any real number that can be printed with arbitrarily long representation, given enough time, by a NPTM starting from an empty tape. Lets also say that a number is computed by a given NPTM iff it either halts after printing a well formed real number (in which case, the number has a finite decimal representation) or will, in a finite amount of time, print well formed number with a decimal point, and will ever increase the precision of the number by printing more digits, given ever more time.
This later condition needed because, if we have a machine that, for instance, prints an infinite sequence of some digit, say 1111111111111111111..., it cannot be said to be computing any real number, because real numbers only have infinite representation to the right side of the decimal period. On the other hand, if the machine prints 3.14 and then stops printing, but never halts, it cannot be said to be computing any real number simply because the precision of the number is not increasing, thus, this particular machine won't be constructing it further.
These are examples of NPTM that do computes some number. A NPTM that:

prints 1, then halts. It computes number 1.
prints 1.0, then halts. It also computes number 1.
prints 1.0000000, and keeps printing zeros forever. This one also computes number 1.
prints 3.14, then halts. It computes number 3.14.
prints 3.14159, and goes on forever printing digits of $\pi$. This one computes number $\pi$.
prints -42., and then halts. It computes number -42.

And these are examples of NPTM that do not compute any number. A NPTM that:

prints 123123123 and then goes on printing the sequence 123 forever. Isn't computing a number because this infinite sequence does not represent any real number.
prints 1.0.0 and then halts. Isn't because this finite sequence is not well formed.
prints ....-..--- and then halts. Isn't because this is not a well formed real number either.
never prints anything, but never halts either. There is no number being constructed.
never prints anything and immediately halts. No number was constructed.
prints 3.14, doesn't halt, but never prints anything else either. Isn't computing a number because its precision isn't increasing with time.

You've got the idea. Then we have two classes of NPTM: those that computes some real number, and those who don't.
The problem with finding some enumeration for the computable numbers is that, even if the NPTM are themselves countable, we can't have a procedure that separates one kind of NPTM from another.
Consider the definition of countable set: for a set $S$ to be countable, there must exist some bijective function $F:  \mathbb{N} \rightarrow S$.
To "prove" that the computable numbers are countable, one might be tempted to define such a function from the counting of the NPTM (and this is what people often did, when they believe the computable numbers are countable). Something like this:
The NPTM are countable, so there is a bijective function $E_\text{NPTM}: \mathbb{N} -> \text{NPTM}$, thus we can go enumerating forever all NPTM that exists. So, to likewise enumerate all computable numbers, and precisely define the bijective function $E_\text{Computabe}:  \mathbb{N} \rightarrow \text{Computable}$, one must simply enumerate all NPTM, but count only those that do compute some real number. But how do we know it computes some real number?
Well, we don't. Consider a machine that immediately prints 1.0, and then stops printing and goes on to try to solve an instance of the Post correspondence problem. If it solves the problem, it halts, then the machine just computed the number one. But that problem is undecidable, so it may never halt, and if it never halts, it never computes a real number. But we can't know if it will ever halt, because the Halting problem is also undecidable! So, since there is no way of knowing if this particular machine, and infinitely many other machines, either computes or not some real number, we can't build/define our bijective function in this way.
The naïve way to define the bijection fails, and it is not very difficult to prove that there is no way do it, whatsoever. As Yuval Filmus suggested, diagonalization can be used.
Comment: You probably wanted to say "computable numbers are not enumerable" instead of "computable numbers are not countable".


Connecting to public proxy servers

Question: I use public proxies a lot. I was wondering, is it possible that they can modify the html and send back malicious javascript, etc?
Comment: possible duplicate of http://security.stackexchange.com/questions/63830/safety-of-using-online-proxy
Comment: @Ulkoma: The linked post discusses web based proxies rather than proxy servers (I've just edited it to make that clear).
Comment: Yes, and it is a surprisingly simple to do and powerful exploit. This public presentation given at the BlackHat conference 2012 demonstrates how it works: [Owning Bad Guys And Mafia With Javascript Botnets](https://www.youtube.com/watch?v=ZCNZJ_7f0Hk)
Answer: Yes, absolutely.  This is a classic man-in-the-middle attack.  All traffic (encrypted or not) runs through the server before being passed to you.  It would be trivial to read (and modify) unencrypted traffic (so anything over HTTP).
HTTPS is different.  As long as it's not a web based proxy, I think you'll be fine as long as you check the certificate is correct and valid for the site you're visiting. This is because to view your traffic, they would have to be able to unencrypt the traffic and then reencrypt it to you.  This means they would have to present you with a certificate signed for a domain they own and not signed for say, https://Google.com.
Comment: So it would still work if the target website didn't have TLS/SSL?
Comment: Oh yes, without TLS/SSL all traffic is sent in plaintext over the network, and can be easily intercepted and read/modified. You would have absolutely no idea it has happened either. You should assume anything sent over http is readable by anyone.

Connecting to public proxy servers


My passport containing Schengen visa completely washed prior to start of my trip to a Schengen state, now what do I have to do to get new visa?

Question: I'm Afghan citizen and still in my country (Afghanistan), I received Schengen visa from Swiss embassy in Pakistan and now my passport containing Schengen visa is completely washed prior to start of my trip to Swiss for a training, now I got my second passport from my country and what to know whether I can get a new Schengen visa or not? and what do I have to do to get new visa? What documents do I have to have? And how long re-issuing Schengen visa will take?
Comment: Did you try contacting the relevant consulate?
Comment: BTW, I cannot understand "visa is completely washed". Do you mean literally in a washing machine? Does it happen a lot, with other important stuff too?
Comment: It is weekend and the the relevant consulate is off. in other hand, I have very short time to start my trip.
Comment: You will have to get your Schengen visa reissued. You will need to go through the whole visa application process again. This is the rule for several countries I have experience with, so I assume it is the same with Schengen visa.
Comment: Can you show that embassy your damaged passport, and that you have it canceled by the issuing authority? Then they may stamp another visa on your new passport. In my opinion, you must show them that your previous passport cannot be used at all in future.
Answer: To re-issue the existing visa, you need to make an appointment directly at the embassy. Call them at  +92518485836 and request for an appointment and explain the situation.
They will be the best to guide you further.
Answer: As stated by Timatic, the database used by airlines:

Valid visas in full, invalidated travel documents are
    accepted provided accompanied by a new travel document.

So if the visa is still in acceptable condition (legible with the machine code intact), you just need to bring both passports. At the Swiss border, present the old passport open at the visa page, and the new one open at the main ID page.
If the visa is damaged as well, you need to get it re-issued. Contact the Swiss embassy regarding this
Answer: Now you must apply new visa application with all same documents and photocopies attached With old passport. And also submit a cover letter to explain what happened with the old passport and apologize for reapply the visa.
Comment: I doubt this is right. Normally you would have to report the loss of your passport (with information as precise as possible) and re-obtain the old visa.


Make people sound younger?

Question: Hey guys, just wanted to ask, is there any way to take an older males voice and make it sound like a younger version of that person? Is there some way to change the pitch or something? Or should I rather get that actor to try and sound younger when he speaks?
Thank you
Answer: This depends a lot on the amount of "years" you want to change.
In most cases getting the right voice actor for the role will give you the most natural results.
Nevertheless you might be in a situation where you don't have the option anymore to look for s.o. or whatever…
If you want to make an adult into a child simple pitch shift (built in ProTools or other workstation or external PlugIn) might work. It did on a couple of occasions. But usually only short sentences or single words.
Pitch it by a good bit and try what amount sounds most natural. But keep in mind that for more than just one word or so pronunciation, melody and rhythm of a child are also very different than those of kids. So there is also a performance factor for this.
Another try might be IRCAM Trax from Flux. (http://www.fluxhome.com/products/plug_ins/ircam_trax) It does advertise as changing male into female and age and so on, but I'd be careful and not expect too much of it. Personally I only tried it once and had the feeling it either works for very subtle changes or very artificial results.
But maybe it's worth a try in you case?
Hope any of this helps.
good luck!
Comment: At my day job we use a pitch shifter to change our actors voices in real time, and it's all in the acting.  The pitch helps seal the deal, but if they don't vocally act the part they're supposed to be playing it just ruins it.
Answer: I've had small successes with pitch shifting, but typically do a small amount of formant shifting also ( < +1.5 semi). But that was when I was stuck with what I had.
Don't forget to EQ as well. If you're trying to make a grown adult sound like a smaller child, you're taking about a different sized resonant cavity. Adjust accordingly.
True success will completely depend on the performance of your talent. If you're asking this before the record, see if the talent can produce the desired results. If not, lobby to find additional talent to speak the younger lines. In the end it'll be a much more natural sounding result.
Answer: +1 for Steve's suggestion of formant shifting. Melodyne can be useful. Antares Throat has worked well - sometimes.
You will be better off getting the actor to record the lines 'younger' because it's usually not just the pitch but things like grain in the voice, pauses between words and enunciation that makes the difference.
Comment: In terms of formant (and pitch)shifting you might want to try Elastique from Zplane. (http://products.zplane.de/index.php?page=elastiquepitch) Might be nice to find a setting for itch and formant independently, but in real time. Also maybe while recording (mind possible latency) like Dave Matney suggested.
Answer: This is going to be hard to produce with processing...at least, it will be if you want it to sound natural. It will be far more effective to capture it as a performance. If you get an actor who can make themselves sound "a little younger," then a small amount of pitch processing afterwards will help sell the difference and give you a final product with fewer artifacts.
That's a pretty standard idea for any sound you're trying to create. Get as close to the ideal sound as possible in the recording, and then use processing to get the rest of the way....cleaner results and more effective sound design.
Answer: Take a look on this link, it's an awesome plug developped by IRCAM (french audio research institue) called Flux from a plugin serie named Trax : http://www.youtube.com/watch?v=S85W-9ePC54
There's a total of 12 stuning episodes. I really would like to try this out.
Comment: I don't know. I watched a few of the videos, and the results sounded pretty atrocious to me. Might work well on something other than voice, but I was unimpressed in this context.

Make people sound younger?


Is there a drawback for local log in compared to server log in?

Question: For developing a mobile app, there is a choice of storing usernames and password data in the device itself, or in a server (user will be authenticated to a server). Other than possibly the user have to manage multiple passwords if he has multiple devices, is there a drawback for the former choice? Also, the app is supposed to connect to internet anyway, so "no internet connection" is not an issue.
Comment: If the server is compromised what consequence would that have?
Answer: You need to clarify your question to get a more helpful response.
Here's the generic answer: storing authentication credentials on a device puts those credentials at risk of offline attack. If a device is responsible for saying it is authenticated, then the somebody may spoof it.
Credential caching is not without merit or precedent. Windows systems perform credential caching for network-disconnected logins.


Linux backdoors I should be wary of

Question: I'm new to the server management realm and I'm sure my server is very insecure.  I've gone through the WHM CPanel security check but I'm sure to the real gurus, that check is stupid and nowhere near what it needs to be.  What are a few things I should look out for?
Answer: I answered a similar question the other day here:
Secure LAMP server for production use
To check for compromise..
Suspicious files in /tmp.  Files in the Web tree unexpected.
Kernel modules loaded that look suspicious. (lsmod)
Processes running that shouldn't be. (ps aufx)
Active network connections. (netstat)
Currently open file descriptors. (lsof)
Ultimately, if the server is compromised, the proper thing to do is to isolate, image, and rebuild.
Edit 1
Bart brought up very good points; especially that you can't trust the local system at all if believed to be compromised.
Once imaged, you can manipulate the image (and filesystems) using known trusted utilities for further forensics.
Dumping traffic on a switch or running a tcpdump on the local system could be useful as well.
Edit 2
I've actually copied utilities from a known good system and used on a remote server before.  Not ideal, but better than nothing.
Comment: This is assuming that if it was compromised, the binaries weren't replaced with binaries that hide the rootkit or processes doing bad things, right? ;-)
Comment: The only other ways to check: unusual network traffic from the odd machine, use a read-only filesystem (devil linux I think is the one that's CD based) so it can't be altered, or boot from a bootable disk to check with hashed file lists kept on read-only media, kind of like what Tripwire does...those are the ones I know of.
Comment: Hmm...what else...install chkrootkit and rkhunter to check for common rootkits, maybe clamav but it's not really suited for catching non-emailed and spam type malware on Linux systems (it's ideal for plugging into mail servers...)
Comment: I'd also add that best practices say you shouldn't run as root or with privileges unless you have to for particular tasks, and you shouldn't allow other users to have your root access; limit what they can do through sudo (where at least it's logged, unless they wipe the logs).
Answer: I already made some points in comments, but to consolidate some thoughts...
You're asking about what, potential attack vectors?
Out of box, there's not a lot on today's Linux installs that you normally need to worry about right away. Most people introduce holes in their Linux systems by installing new programs and altering configs.
In order to give you better advice, you need to clarify what you're doing. A home server? A database server? Web server? Workstation?
A system with all patches and updates will still expose information if you're running a database server that doesn't clean up input and manages to have an SQL injection attack against a backend database.
Generally, you do what you need to do on any other system. Update regularly. Use the least privileges necessary to do something (don't run as root all the time). Don't login with cleartext passwords (use SSH to remotely administer the system). Don't run unnecessary services (turn off remote desktop/VNC if you're not using it, don't run a web server if you're not using it, etc.) Use strong passwords. Check logs regularly for unusual behavior. Get to know how your system acts so you know what's "weird". Monitor logs for unusual access attempts. Install denyhosts and configure it to lock out IP's that try knocking on SSH for login access, or move it a few ports so it's not open to bot attack. Use NMAP to check what ports you have open (from another machine). Audit your machine with something like SAINT (google for vulnerability auditing tools). Don't leave your workstation logged in when you walk away.
Things like chkrootkit and rkhunter help give some guidance and peace of mind, as do hashing utilities like tripwire, but they add to your maintenance. You need to sit down and balance usability with security needs, and apply them as needed (is it worth the extra hash generation and storage each time you alter a set of files or run system updates, vs. what you have to potentially lose in time and money if the server is lost?)
Make sure you have a good backup routine. A copy of live data is no good if someone compromises the server and your oldest backups contain the compromise.
Never trust a system if you think it has been compromised. I like using devil linux for appliance purposes because it is impossible to crack outside of data scratch areas (things like proxy servers); it boots and runs from CD, so no one can replace the binaries. I suppose they can patch them in memory, but a reboot clears it.
If you are dealing with heavier security needs, echo your logs to another server. Don't use the same password for everything. If your server is compromised, they get access to all passwords (I read once about someone setting up a porn site, then watching logins and email addresses and such coming into the logs...they figured they could then turn around and use those same passwords to crack into other sites, since most people use the same password scheme in the workplace and home as they do for commercial sites).
Those are the big ones. Again it's all a matter of balancing usability with security and how much you have to lose if you lose the server, but also things on your network. If someone takes over a humble little file server or hardly used in-house web server, Linux can easily be used to redirect ARP requests and act as a router to sniff traffic so it can see other things on your network, so even an insignificant server can become a significant threat. Since you didn't say what the server and role was or what the location is, it's hard to tell you specifics (like, "Whoa! you don't want to touch credit card information storage if you have to ask about it! That stuff is heavily regulated!" or, "Never store passwords unhashed. Never store as plain text, ever.")
Answer: chkrootkit and rkhunter
Answer: While this is wildly complicated (Dont say i didn't warn you). NeXpose has a Community Edition[rapid7.com] you can use to scan for vulnerabilities. You can also integrate it with Metasploit[www.metaploit.com]. Be prepared to do some heavy reading. But if you wade through it, you will be wiser. These are even tools used by some security professionals.
Engage the community and study! Being compromised (and to compromise) can be very intricate.
Best bet if you are or suspect that you are compromised, reinstall from backups or make  a clean install. Use sources that provides checksums[en.wikipedia.com] for downloads
If they know what they are doing, they could even modify compilers on your system to compile in "malware" on new compiles.
EDIT: These are tools to check if you can be exploited. They will not check if you are compromised.

Linux backdoors I should be wary of


What is Physics Overflow and how is it linked to Physics.SE?

Question: A community ad caught my eye, and I visited http://www.physicsoverflow.org. What are the links between Physics SE and Physics Overflow and how are they different from each other?
Comment: On a side note, you can help with [community ads by voting](http://meta.physics.stackexchange.com/questions/5263).
Comment: I've moved the conversation [to chat](http://chat.stackexchange.com/rooms/17799); please take any further discussion there.
Comment: related: http://meta.stackexchange.com/q/240839/
Answer: PhysicsOverflow is meant to be some kind of a rebirth of the untimely passed away Theoretical Physics SE and a little physics brother of MathOverflow.
Compared to the former theoretical physics site, we have slightly lowered the bar to ask questions to graduate-level upward and broadened the scope to include experimental physics and phenomenology.
Apart from the high-level Q&A, PhysicsOverflow offers also a Reviews section, dedicated to discuss and peer review (mostly ArXiv but other sources can be considered too) papers publicly and "in real time".
PhysicsOverflow was built outside the SE network to not have to fullfill any externally prescribed activity criteria for graduation (Area51 statistics). As Danu hinted at, this also allows us to avoid having to obey the "SE model" or SE rules, policies, and guidelines where they would clash with the goals of a high-level academic community (MathOverflow negociated a special agreement with SE before joining the network).
You can find a full description of the site in our FAQ and a short summary of its purpose in our official announcement on MathOverflow.
Comment: Greetings or hello or dignified hello or get lost was their first hello?
Answer: PhysicsOverflow was started by a number of users that were not content with the way the SE network works - especially in terms of moderation. They are not affiliated with the SE network. Furthermore, PO is more strict about the level of questions, accepting only questions of graduate level or higher.
Answer: One thing to keep in mind, which was mentioned comments that are now in chat, is that the moderation policies and atmosphere at Physics Overflow do not necessarily match the ones here at Physics Stack Exchange. This can be a good thing or a bad thing, depending of your opinion of the atmosphere thing.
The main difference, in my understanding, is that (as PO sees it), they will not moderate 'frankness' in speech when used to convey physics content. This is something the Physics Overflow organizers and community seem to feel happens here; to quote from their FAQ:

Stack Exchange discourages and censors scientific criticism, and has admitted to have been systematically blocking frankness.

A less charitable view is that PO will let slide a good bit more unpoliteness than you'll see here. It is certainly the case that their stance towards abuse is relatively hazy. The main thing that worries me about PO is well encapsulated by the question Will there be politeness policies on physics overflow?. As Dilaton pointed out, Arnold Neumaier's answer there is quite moderate,

It is not necessary to be rude, and paying a little attention to one's tone is certainly better than just writing from one's gut feelings. A moderate language is one of the many facets of perfection, to be aspired even if not always attained.

and it is the highest-voted answer. However, that answer is hardly conclusive, and it seems that the hard stance is that

There are no rudeness rules, and there will never be.

as commented by a PO moderator.
They do have a section What can I do if I observe bad things? on their FAQ, which I feel is hazy regarding abuse on the site, directing readers to a contact link. Mostly, they really shy away from providing any guidelines on what sort of behaviour is and is not acceptable on the site. Personally, I would be worried that certain types of very cutting ad hominem attacks - of the kind that has been observed and frowned upon on this site before - will be given a lot of free rein on PO.
Now, PO moderators have stated informally that abuse will not be tolerated there, but I'm not sure how that squares with the comment above. At the very least, this is unclear and confusing as a PO user; personally, I would expect that some pretty bad stuff will inevitably slip through the cracks of that lack of clarity. I do not, however, advise people curious about PO to stay away from the site - instead, be aware of these points and make up your own mind whether you want to be part of that community.
For contrast, you can see the "Be Nice" policy at Stack Exchange, and the previous one (active until October 2014). I, for one, do not see anything there that even hints at scientific censorship. It sure feels good to use belittling language when critiquing work that I feel is technically incorrect, but in the end (I think) it only diminishes the quality of my writing, its value to its readers, and the chances that it will be taken seriously. But then, that's just me.
Personally, I would like PO to adopt an approach like arXiv Analytics, which states on its front page, in crisp and clear language, that

We encourage frank, open, and constructive conversation, but frankness doesn't mean lack of civility or lack of respect for others.

It seems, though, that they're still reluctant to put any qualifiers behind 'frankness is allowed'.
Comment: @Ron if you think so and you don't want to re-examine the view then you're entitled to that. All I'm saying is that it's a classic design mistake to say "everything is perfectly easy to find because I know where it is". It is a real pitfall and it takes a lot of willingness to hear from actual users to admit that one's design isn't optimal. Feel free to brush off my opinion as an 'outlier' if it makes you feel more comfortable, but don't tell me as a user that I didn't have a hard time finding the stuff I wanted from your site.
Comment: When people criticise scientific work bluntly, it often happens that people's feelings get hurt, and this happens even when there is no actual incivility. When moderators try to control the language in a top-down way, the imbalance of power between moderators and users leads the moderators to oppress users they don't like. The result is that the moderators make the disliked users' experience unbearable, including outright blocks, as happened to me here. To avoid this phenomenon, following Arnold Neumaier's suggestion, rudeness is only controlled by users editing each other, not by moderators.
Comment: This bottom-up policy is essential for an academic group, because when you are criticising a wrong paper, the author is sure you are wrong, and his natural impulse is to run to the moderators and seek redress by censorship. The author will accuse you of being ignorant, or deluded. I was accused of this on PO when I criticized one users' scientific publication even while I was moderator, the user asked Dilaton to block me. The pressure for censorship is enormous, and it has stifled free discussions in many places. Arnold's method lets us have our cake and eat it too, as it controls rudeness.
Comment: I would suggest you ask someone to perform an audit with that in mind, and act accordingly. The correct response to "I had a hard time finding X" is not "but X is right under Y" but rather "shit! How can I make it clearer where X is?".
Comment: @Dimensio1n0 If you mean "Stack Exchange discourages and censors scientific criticism, and has admitted to have been systematically blocking frankness", this is [still present](http://www.physicsoverflow.org/faq#a4811). If you mean something else, please clarify.
Comment: Ron, I don't really think this is the place to criticize the moderation or to expound on abstract theories of the internet. If you feel my description is inaccurate, I'm happy to hear why. If you have a space where you have these arguments explored in a reasonable fashion, or a PO page that describes actual on-site practices, I'm happy to link to it. Otherwise, this really should be posted as an answer of its own.
Comment: @EmilioPisanty: You are claiming that because PO does not have punitive policy regarding rudeness, that means that PO tolerates rudeness, which is implicitly assuming that top-down methods are the only way to control rudeness. PO implemented a bottom-up method which works much better, and preserves the freedom of users.
Comment: That's not at all how I see it but this is where I get off the bus. I do hope PO works as a model, despite what you might think. I just wish you guys were clearer and more upfront about what you're doing, is all.
Comment: @Dimensio1n0 What you're asking for is a (second) website audit which is a nontrivial job. I can tell you I had a very hard time assembling the information in my answer, and I don't have time to repeat that. I can understand that you feel the information is all there, because you know where it is, but communication is a two-person job, and if someone who is genuinely looking for the information can't find it, then you have a problem.
Comment: I'm more of a computer scientist than a physics guy. In that domain, I am quite the contrarian in areas like performance diagnosis and languages for user interfaces. But as much as there is disagreement, I have never been tempted to tell somebody to their face that they are wrong (if that is what frankness is). I simply state the argument as clearly as I can. Where all this tension comes from is a mystery to me. It's not like our livelihood is at stake.
Comment: PO's approach is not too different from ArXiV analytics, really. The line you quote only says that arxiv analytics does not encourage, or perhaps discourages incivility. PO does the same.
Comment: @EmilioPisanty Thanks for the nice words, but I think we're very clear and upfront about what we're doing (for starters, the moderator manual is public). What do you think needs to be more transparent (genuinely asking)?
Comment: Also, I'd like to add that the section you quoted is no longer present in the FAQ. That is old, and from an era when the fiery formation of PO had just happened.
Comment: I stand corrected, thanks (+1), I'll fix that. The FAQ does need a lot of updating, as you can see : )
Comment: @EmilioPisanty: There is nothing hard to find, everything is crystal clear.
Answer: preamble:- I don't really have any hard feelings against SE any longer; I honestly do understand their point of view and way of functioning. It's just that the goals of PO are very different from those of StackExchange. I also figured out that a lot of my complaints when active here were unjustified (I'm talking about the "wrong answers should be deleted" nonsense that I liked to spread).

There are fundamental differences between PhysicsOverflow and Physics Stack Exchange, besides just the scope and level. Dilaton has already mentioned the difference in scope and level, but received a lot of flak for not mentioning what I initially thought were minor differences in policy, but upon further thought are actually important to point out, as mentioned by Emilio Pisanty and others.
The main goal of PO is to support academic communities. SE's main goal is to support a library of interesting content (as their unofficial motto says, to "make the internet better". I think both points of view are perfectly reasonable.
This fundamental difference is from where a lot of the policy differences come from. For instance, PhysicsOverflow has a user rights document, the moderator manual is made public and prominent from the PO homepage, and so on. PO's reviews section is a completely original idea, although there's also ArXiV-Analytics, but there are subtle differences which means the two aren't competitors either.
Comments are viewed as first-class citizens on PO, as they are important for an open discussion forum. Stack Exchange views them as somewhat inferior forms of content, again, because they do hinder the goal of forming neat Q&A libraries.
It's also true that PO does not have strict rules against rudeness. We have, however, recently adopted some guidelines that encourage politeness, although don't mandate them. It's a surprising kind of propaganda spread in a number of places that we somehow "encourage" rudeness. We absolutely don't.
The comments about "what if sexism/racism arises? will that be removed?" seem to be a sort of appeal to emotion, but anyway - such content rarely arises on a professional physics site, and is illegal in a number of countries, including the European Union where PO's servers are hosted, and where PO's registrant lives, and therefore does become a natural exception to the user rights.
Coming to the relationship between the two sites, PhysicsOverflow has zero issues with PSE. Links to answers on PSE are completely welcome (although it is preferred to link to an imported copy, as those tend too have more content), and PhysicsOverflow very much does want to maintain at least a neutral, if not a cordial relationship with Physics.SE. In fact, we even link to Physics.SE in the email we send to newly registered users, the relevant section is:

Popular physics questions and Undergraduate/K-12 level questions are better suited on Quora or Physics Stack Exchange; Purely mathematical questions (that are not relevant for physicists) will be better received on MathOverflow if research-level, and Mathematics Stack Exchange if not.

Unfortunately, this feeling is not reciprocated from the other side. While I understand the reason for my ban for "promotional content" (although I would have preferred a warning beforehand), I really do not understand the reason for Dilaton's ban for the same stated pretext; Dilaton only posted links to PO threads once the questions were actually answered, yet was suspended for a year for doing so. I wonder if SE would have a similiar reaction, if a user posted links to Wikipedia, or Quora, or Physicsforums, or another Stack Exchange site repeatedly. Is it so bad to post some useful links to help the OP and other people interested in the question? I mean, you guys even made a script to delete all links to PO here! What was that?
I hope to see these issues resolved soon, because unlike say, PF, PO is not intended to be a competitor to PSE at all, rather a completely different platform.
Comment: That script is a little concerning with its title but was it actually used to delete comments or just to flag /notice them? I can't see why any site would prefer to have comments deleted that were not spam if they linked to useful answers
Answer: Upon forceful deletion of my previous answer, by some users I will be reviewing once again some differences between Physics overflow and stack exchange. I will be brief in my answer, factual and less passionate.
1) Physics Stack Exchange imposes,(Sometimes even year long) suspensions of accounts. The details of the which are kept hidden from the users. It is only the moderators, and members of the stack exchange family who make the decisions, and it has happened despite protest from the larger userbase.
Physics overflow does not allow for this kind of closed door policies, and as yet there have been no instances of banning users in the site.
2) Physics overflow, operates with the policy that a User's content will be be protected in the form that the user wishes to preserve. It makes exceptions for spam and other severe or legal abuses. Users or moderators cannot remove any disagreeable content, and Bad content is subject to review through discussion and not through unilateral deletion.
Physics stack exchange allows for moderators to close questions directly, If they find the content to be disagreeable. Its relies on the trust its places on the moderators to be fair with their judgements. Any disagreeable content(an example being my previous answer) is removed, without allowing for the natural process of peer review, down-voting etc, if the moderators(or other high reputation users) feel it to be appropriate.
3) Physics Overflow Implements Rotating of moderator positions(currently 1 yr cycle), to facilitate the process of understanding the position of both the moderators and users from a practical point of view.
Physics Stack Exchange implements Life time moderatorship. Some reasons being listed here.
These are some of the differences between the sites, apart from obvious ones such as their intended audience.
Comment: 1) Is not completely accurate, there was the case of a PO moderator deleteing posts to make a user look bad and then messing with that user's account, effectively suspending them.   2) Is an exaggeration, moderators often appear to be acting on their own, but are actually taking actions based on flags raised by others.  And your previous answer wasn't removed because it was disagreeable, it was removed because it didn't really answer the question.
Comment: @ward Reguarding 1) I am aware of the issue, and It was agreed that the moderator made a mistake, and The user involved is still in the site, and the situation was resolved to my satisfaction. 2) Are flags openly visible? How is user supposed to know about the flags? I got no notification of my post being flagged, Not did nor did I get a chance to address the reasons for my post being flagged.
Comment: This is just my opinion, but I think that this is a much better answer than your previous one.
Comment: *nor did I get a chance to address the reasons for my post being flagged* in most every case I have seen, one of the many non-mod reviewers (generally 3k+ rep, but sometimes 10k+) will leave an automatically generated phrase that says exactly *why* a post is being threatened with deletion. There are also well-known automatic deletion scripts acting on all SE sites. Just because *you* aren't aware doesn't mean it doesn't exist.


Adjusting disk brakes after taking off the wheel

Question: I recently took off the front wheel off of my mountain bike, and have been having considerably difficulty getting the front wheel on the right spot such that the wheel doesn't rub against the brake when I'm riding. I know there is clearance possible, because if I pull the quick release on my wheel and turn the wheel, it spins just fine. What can I do to align the brake properly?
Comment: More than 50% of the time I take off a wheel, I have this problem. I would be ***VERY*** interested to know ***why*** is this happening. Then how to prevent it, instead of re-adjusting a disc brake after every tube change / tube repair!
Comment: As it happens intermittently, have you checked for a broken axle?
Comment: @mattnz: I doubt it, it's more likely just that I can't line everything up right. I can get it to line up better sometimes, but when I started noticing this problem, I was well down the road, so... Still, thanks for the possibility!
Answer: Tip of the day for how to adjust brakes so they dont rub when tightened:
Use shims on either side of the disk!
Here's how to do it:

Get a beer can and cut a strip about an inch wide and 6 inches long (careful when using this, it's sharp)
Take the wheel off the bike, loosen up the hex cap bolts on top of the calliper, not the wheel, adaptor, etc
Put the shim over disk, in the position where the calliper will float over it, put the wheel back in so the shim is now jammed up into the loosened calliper and do up your quick release nice and tight
Put the brake on a little (to centre the calliper) and tighten up the calliper bolts.
Remove the shim (you may have to remove the wheel) and you should have a really properly aligned brake (either cable or hydraulic).

Make sure your beer can strip is really clean (use soapy water and properly rinse) so you don't contaminate the pads or disk.
I've got Avid Juicy brakes and I had huge problems with getting them properly aligned so they didn't make little squealing sounds whenever I was riding (they never really rubbed) and this made it so much more pleasant!
Answer: Assuming you mean that the disk caliper pads are rubbing on the rotor when the lever is not being used/squeezed:
1) The fixed/non-moving pad/side in the caliper on my brakes are adjusted with an allen key from that outer side of the caliper. If it has been a while this bolt could require some effort to get moving.  On my brakes there is a detent such that I back off the bolt one click at a time and see how the clearance is.
2) The moving pad/side in the caliper is adjusted by cable tension in the usual way, i.e. with the barrel adjuster at the lever or the pinch bolt at the caliper.
Comment: @Vorac - are you saying you make the adjustment and it is rubbing again next time? Or sometimes it rubs and sometimes it doesn't after wheel removal/replacement?  If the former, you might have a rotor that is warping
Comment: @David Sopko - when the skewer is locked down, the fork drop-out is pinched between the bearing/cone and the skewer nuts.  Backing off a bit would mean that the dropout is not being pinched as tightly.  If the skewer is loosened enough to have *any* effect on the position of the caliper the wheel will almost certainly be too loose to ride.
Comment: @original poster and everyone else - the first time I had this problem I didn't have a ready access to an allen key to make the adjustment.  What I did for the short term was to make a *very* thin washer/shim by cutting a circle out of a clear plastic package (that some other bike part came in).  I put it over the axle between the drop-out and bearing on the side that was rubbing.  That moves the whole wheel over the width of the shim. But, this is just a *short-term* fix until you make the proper adjustment.
Answer: @Arbalest has the correct answer for one specific problem with brakes with just one cylinder, If that is not it, the best way would be to reset the caliper alignment. I am not expert, theres heaps of information on how to do it - the owners manual is a good start - it's not hard, but a novice may need a couple of goes at it to get it spot on.
Essentially, loosen the bolts holding the caliper enough so it moves, but is not loose. Pump the brakes gently a couple of times with the wheel spinning (in normal direction). Then while applying the brakes "firmly but not hard" (i.e. enough to hold the caliper in place),  slowly tighten the bolts, alternating between them 1/2 turn at a time (so it tightens evenly on each side).
Answer: I've had this problem with more than one bike, and risk factors for that are:

Quick-release hubs (as opposed to 20 mm, thru-axle);
Long travel forks;
"Light" or otherwise delicate forks (even good quality ones);
Mechanical brakes (one pad non-moving);
Large-diameter (8 inch) disks.

The problem is that, due to the very tight distance between the disk and the pads, a minimal amount of "shape changing" creates rub and noise. This shape changing might occur between opening and closing the quick release, or because of more aggressive twisting forces while cornering on difficult terrain.
Usually, a little rubbing is not a real problem, but much more of a nuisance, and even very small rubs can cause an unpleasant noise.
One possible solution, and one that works for me when I'm in an "I need silence" mood, is to catch the front wheel of the bike in a corner, or even against a wall or a tree or a fence, and TWIST THE HANDLEBARS. If you do this gently, you'll notice that the fork twists (a tiny bit of course) enough to make the disk reposition itself inside the caliper, also showing the direction you should apply a greater force to reposition the disk/caliper "permanently", and this is enough to solve the problem, but only if the rubbing is minimal (otherwise it is necessary to properly adjust the brake).
Of course I am not suggesting to twist anything in a way that would cause damage, but I think some setups are so prone to misalignments that the same poison should cure the disease, and that's it.
Also, of course this problem has a WAY smaller chance to happen with non-quick-release. 20mm thru-axle hubs/forks.
Hope this helps!
Answer: When using QR axles (my preference FWIW) with disc brakes, it's important to make sure the wheel gets seated in the fork ends exactly the same every time, and that it doesn't shift in riding. QR axles can cause tiny differences in wheel position, which never mattered with rim brakes, but which can cause hassles with disc brakes rubbing.
My method:
--mark your axles and install them with the same rotation every time. This is easy with my dynamo hub because I rotate the electrical plug straight up every time. For other hubs, I mark one flat of the axle lock nuts and install that flat straight up every time.
--cram the wheel completely into the fork ends while tightening the QR. This ensures a consistent position and reduces chances of the wheel shifting from a bump. I tighten my QR from the riding position, while leaning my full weight into the handlebars with my waist, pressing the wheel fully up into the fork ends.
--use a good QR. Any internal cam Shimano QR is fine or most any QR with INTERNAL CAM. The QR's with the external cams go in the trash. In my experience they are marginal anyway and right out for a disk brake world.
After doing the above, I use the typical business card method to adjust the brake caliper position. There is no need or benefit to shimming the rotor unless you cannot adjust the caliper enough without the shim, or unless you want to be able to swap different wheels, then shimming the rotor can make sense
With these practices I have no problems anymore with disc brake clearance shifting when changing a wheel, and I even run a 203mm front rotor and a cable caliper with single-piston design on my cargo bike with no problems. I'm also slightly picky able my lever slack and engagement.
Comment: Why do you prefer QR for disc brakes?
Answer: This is a recurring problem with QR (as opposed to 12mm, 20mm through-axles).
Turn the bike upside down so gravity helps you with re-seating the wheeel.
Attempt to install the wheel (push and rock it well into the dropout); then engage the breaks a couple of times to reset the pistons; rotate the wheel; hope for no rub. Do this multiple times, as it is far faster and easier than other techniques.
If it fails, refer to the other answers. Your disc could be wrapped, your caliper could be off-center, your pads could be mis-aligned, mis-worn, mis-whatever. Good luck and happy riding!
Answer: My best guess to this issue is a mismatch in tolerances.  The disk brake tolerance is quite tight to ensure zero rubbing.  For example, the my thru the axle mount — even though I obsessively try to get the wheel to seat the same way as when I aligned the brakes — upon tightening the axle the tolerance in the wheel mounting causes the wheel to cant a small amount and hence causing brake rubbing.
Comment: Hi, welcome to bicycles.  If you have a question of your own that is not answered here you should [ask it](https://bicycles.stackexchange.com/questions/ask) instead of posting a follow-up question as an answer.  You might want to take the [tour].


How much more paint does a paint sprayer use than a roller?

Question: I am going to be painting the inside of my 2-story home except for the bedrooms, so I have a fairly large area to cover.  How much more paint would a paint sprayer use, compared to using paint rollers?  We are considering using Sherman Williams paint and don't want our expenses to get out of hand.
Comment: I would assume that a sprayer will use more paint than a roller, which in turn uses more paint than a brush. Obviously the finish is different in each case.
Comment: Yeah I've heard that a sprayer uses more; I'm just curious roughly how much more (such as a percentage, as an estimate).
Comment: I meant to say "quite a bit" - but I have no data, hence the comment.
Comment: That makes sense.  I hadn't thought about how the finish would look in each case.
Answer: I have used a sprayer to paint my house before we moved in. While I can't qualify how much more paint I used, it did feel like I used more compared to rolling, but I think part of that is because it goes so quick and I may have been painting over the same areas more than I would have with a roller.
One thing to note though, when I sprayed my home, there was nothing in it. No flooring, window treatments, etc.  Spraying, no matter how careful, will leave some atomized paint in the air, which will eventually hit the floor or whatever else you don't want to have paint on it. Be prepared to mask, tape, and tarp everything you don't want painted that can't be removed from the room. You will want a mask and a respirator of some kind (you probably don't need anything fancy). The mask I used had a roll of film built in it so that I could get a "clean view" when too much paint got on it. That was especially handy when doing the ceilings.
Personally, now that I have moved in, I would roll instead of spray.
Answer: High Volume Low Pressure HVLP will probably be comparable.  I have used a High Pressure cannister/gun with my air compressor and wasted a ton of paint to the air.  The HVLP sprayers are supposed to be pretty good now.


Donating and volunteering geographical knowledge?

Question: I know a lot about the places I visit, and I want to share it with everyone.
I have been donating and volunteering at OpenStreetMap, and I am also aware of Google Maps.
Where else can I help with collaborative mapping?
Answer:
This question has been converted to Community Wiki and wiki locked
  because it is an example of a question that seeks a list of answers
  and appears to be popular enough to protect it from closure.  It
  should be treated as a special case and should not be viewed as the
  type of question that is encouraged on this, or any Stack Exchange
  site, but if you wish to contribute more content to it then feel free
  to do so by editing this answer.

Of course it is ultimately up to you, but i would hesitate to call working with OpenStreetMap a waste of time.
While it is true that the OSM user base is small right now, there are factors that affect both Google and OSM. The primary issue is that now that Google has started to charge for levels of use of their API, a number of companies and organizations are switching to OSM. The list includes Apple, Foursquare, and Wikipedia mobile apps. It looks like more may switch as well, which could increase the user base significantly.
This is one aspect.
The other, and that which seems more important to me is the idea of open access to data. As a Geographer and GIS professional, having access to high quality datasets is critical for me to do my job. Having access that can not be compromised is even more important. The OSM dataset is licensed as Open Data Commons Open Database License, so anyone may use it. Google data is privately owned and while this likely won't happen, they could close it off tomorrow and charge everyone for access, whether you helped improve the dataset or not.
I know that here in the United States access to data is a big issue.  A lot of time and money is spent collecting and building the datasets, and a big question is who should pick up this cost.  There are arguments either way.  I am sure this is an issue in other parts of the world as well, especially in places where there are not as many sources of data like streets available for people to use.
This is a pretty hot topic you picked here, with strong, valid feelings on both sides.  Google has every right to charge for their data, and make a profit.  People have the same right to build their own dataset and make it available to everyone. There is nothing to say you can't support both, just don't sell one short over the other without researching on your own, and drawing your own conclusions.
Answer: It's worth noting that at Google Maps, you're not 'donating' your geographic knowledge -- you are giving your geographic knowledge to a for-profit corporate entity, who have a duty to their shareholders to use their position as a majority data holder in the worldwide map data market to increase the value of their company.
This means that the data that you give to Google is not necessarily something that you can get back out and do what you want with. For example, if you imagine that you start a business making GPS Maps for Bikes, or some such, down the road, getting the data that you give to Google back out for use in the product you want to sell may be difficult, or simply a violation of the Terms of Service which you would not be allowed to pursue.
OpenStreetMap is openly licensed dataset. It is created and supported by more than 500,000 editors, and the data is available for libre (that is, 'free as in freedom') use under the terms of the ODBL, which would allow you to make the GPS Maps For Bikes app without needing to pay a licensing fee to anyone.
Data you add to Google Maps is collectively licensed to Google. (Your individual contributions presumably have relatively limited value outside the collection of data, as is the case in almost any map-making effort.)  If you do something Google doesn't want, then they can say No, and shut you down. Innovation by third parties outside the scope of what limitations Google provides for is not allowed.
OpenStreetMap data is openly licensed and managed by a non-profit organization dedicated to furthering the use of geographic information around the world. If no one has done the new cool thing that you want to do -- you can get the data, and do it.
Short term, you may get more out of Google -- with a massive corporate investment in user-targeted tools, and a massive investment in initial data -- but over time, OpenStreetMap's openly licensed data is likely to be the more sustainable solution. With half a million editors, and the growing investment from national mapping agencies around the globe, I can't imagine any way in which OSM is not the more appropriate map provider to support for the long term.
Answer: In addition to the other excellent comments here, the biggest advantage I see to OSM data is two aspects of ease of access:

Editing is far more straightforward, particularly with a large area that is previously unmapped, or (worse yet) badly mapped. JOSM, QGIS and other tools let you update large areas, correct or add data in bulk. Working on areas here in Tanzania that are poorly covered by OSM and Google (click links to see example of same area), OSM is far, far better for editing.
With this comes better access to data for offline mapping. While both APIs give you great access to maps (and Google's gives you more options and are prettier), OSM can be downloaded monthly for any area of interest. Google's given us access to road data (shapefiles) for Tanzania before but it takes time.

(1) in particular has been annoying recently. I have battled with Google editors for approval of known bad data, or not had my GPS-derived roads approved because it doesn't match with the 8-year old satellite data!
Of course, the ease of access is only really with us because of the small base of users. The more open it gets, the more problems we'll have with validation and vandalism.
Update: great example of how a community can quickly map poorly-covered areas, see the Ramani Tandale project, which also has an Ushahidi crowdmapping instance running.
Answer: Go with Google. They currently provide a very good free service to everyone in the world for free. It is always being developed by a very large team and the data is very accessible and usable through the Google set of products which millions use.
The mapping architecture and software developed by Google values the user 1st most and Google only makes money from users through the showing of advertisements, not directly charging the user.
Selling API access to their database is reasonable, and only large websites ever have that issue, but who cares? If you're not running a website then it doesn't matter to you at all!


Malware on D7 website - Blacklisted by Google

Question: I want to tell you about the malware attack to my Drupal website. Not just for your suggestions but also to create something helpful to anybody tha could suffer for the same problems. Well...

INITIAL SETUP

Drupal 7.9
Activated modules:

CORE: Block, Contextual links, Database logging, Field, Field SQL storage, Field UI, File, Filter, Image, List, Locale, Menu, Node, Number, Options, Overlay, Path, PHP Filter, RDF, System, Taxonomy, Text, Toolbar, User
CCK: Multiselectd
CHAOS TOOL SUITE: Chaos tools
DATA/ORA: Calendar, Date, Date API, Date Popup, Date views
FIELDS: Email, Field permission, Link
OTHER: Google Plus One +1, Pathauto, Token, Weight
SHARING: Share this, Share this block
TAXONOMY MENU: Taxonomy menu
VIEWS: Views, Views PDF Display, Views PHP, Views UI
OTHER MODULES THAT I REMOVED: CKEDITOR, VIEWS_SLIDESHOW, IMCE, DOMPDF, PRINT, WYSIWIG

MY SETUP ERRORS

In order to satisfy the custome, I modified some of the modules and I've never update them (AUCH!)
The customer was in posses of the login data, and maybe his computer wasn't safe (MMM...)
I didn't have a copy of the webiste, because I trusted on the provider weekly backup (DOH!)

ATTACK EXTERNAL SYMPTOMS

All the link of the homepage redirected to a malware website
Google blacklisted the website
Critical alert on the Google Webmaster Tools panel

FTP SYMPTOMS

Lots of "strange" files: mainma3.php (I found this one in every folder!), functoins.php, sum75.html, wlc.html, aol.zip, chase.zip, chaseverification.zip, 501830549263.php, wp-conf.php and a dozen of wtmXXXXn.php (dove X = numero) in the root folder. All these files was plenty of malicious functions (unescape, base64_decode, eval, etc.)
Install.php was modified with a long line of malicious code
To EVERY javascript files was appended this line of code:
;document.write('');
The weekly backup was also infeceted
Dozen of repeated "strange" request, found on the Drupal log panel (my domain is obscured with the string "-----"):

index.php?q=ckeditor/xss > Notice: Undefined offset: 5 in eval() (linea 29 di /web/htdocs/-----/home/modules/php/php.module(74) : eval()'d code(1) : eval()'d code).
-----/user?destination=node/add > Failed login by shadowke
calendar/week/2012-W19?year=2011&mini=2012-12 > page not found
misc/]};P.optgroup=P.option;P.tbody=P.tfoot=P.colgroup=P.caption=P.thead;P.th=P.td;if(!c.support.htmlSerialize)P._default=[1, > page not found
misc/)h.html(f?c( > page not found
mail.htm > page not found

RECOVER [Thank to this article: http://25yearsofprogramming.com/blog/20070705.htm]

I've put the website on Maintanance mode (error503.php + .htaccess). Traffic open just for my IP Address
[see this useful guide: http://25yearsofprogramming.com/blog/20070704.htm]
I've downloaded the whole website in local
I've searched and removed the strange files > I found forty of them
I've searched the files for these worlds [with the freeware AGENT RANSACK]: eval(base64_decode($POST["php"])), eval(, eval (, base64, document.write, iframe, unescape, var div_colors, var _0x, CoreLibrariesHandler, pingnow, serchbot, km0ae9gr6m, c3284d, upd.php, timthumb. > I've acted in one of the follow ways: a) I've replaced eval with php_eval() (the eval safe version of drupal); b) I've wrote down the suspected modules; c) I've compared the code with the fresh downloaded module; d) I've removed all the malicious code (see the javascript mentioned above)
I've searched for mohanges in the file system [with the freeware WINMERGE]
I've identifyed some suspected modules, thank to the list written at the point 4 above, and thank to some researches on Google (name_of_the_module security issue, name_of_the_module hacked, etc...) and on Secunia [http://secunia.com/community/advisories/search]
I've scan my computer (Avast, Search&Destroy, Malwarebytes Antimalware) > I didn't found any virus or spyware
I've changed all the logins (ftp, cpanel, drupal admin panel)
I've reloaded the whole website
I've removed all the suspected modules: CKEDITOR, VIEWS_SLIDEWHOW, PRINT, DOMPDF, IMCE, CAPTCHA, WYSIWIG, WEBFORM.
I've tell the whole story to the provider assistance
I request Google for a revision (they did it in 12 hours)

DRUPAL LOG NOW
dozen of these messages
- wtm4698n.php?showimg=1&cookies=1 > page not found
- fhd42i3d.html > page not found
- wp-conf.php?t2471n=1 > page not found
- -----/user?destination=node/add > Failed login by Elovogue

LESSONS LEARNED

Never touch the modules, so you can update them
Keep all the login in a safe computer / Use a safe computer to work on the FTP
Search for any security issue before installing a module
Keep a clean copy of the website somewhere

MY QUESTIONS:

What kind of attack I've received?
There are other unsure module in my installation?
What can I do yet?

Thanks to everybody for your patience!
Answer: If you are using m$ windows, I think it is a trojan/virus that steals your ftp passwords and automatically editing files. I know many such stories.
Switch to WinSCP.net.


How does signing work with Elliptic Curve Crypto?

Question: So I have read up and have a decent understanding of how the crypto works with Elliptic Curve Cryptography.  I also think I have an understanding of how signing works with things like Elliptic Curve Digital Signature Algorithm (ECDSA).  The certificate and private key on my web server are both 2048 bit RSA keys.  Can I only do RSA signatures because that is what my keys are?  If I can do things like ECDSA, how is the trust chained from my RSA keys to the ECC keys that are used for signing under ECDSA?
Answer: Elliptic-curve (EC) cryptography is significantly different than traditional RSA-style cryptography.
Bottom-line Up Front (BLUF): Your server can only handle RSA key exchanges given the information you provided.
As a primer, both of these are asymmetric cryptographic protocols. They are used to securely transmit a SYMMETRIC key that both parties use to encrypt the actual data/message. The reason behind this is that asymmetric cryptographic protocols are extremely computationally intensive as compared to symmetric cryptographic protocols (in the general case). So encrypting a large dataset or a streaming message would be resource intensive. Instead, the symmetric key is used.
So back to your question. Your digital signature has been created and signed stating that your public key is a 2048-bit RSA key. That necessarily means that your private key is also an RSA key - You cannot use EC protocols with that digital signature or the keys that you possess. So the answer to your first question is: Yes, you can only do 2048-bit RSA key exchanges on your web server.
To create/generate EC keys you would have to either be issued one (or more) from an upstream provider or generate them yourself via a 3rd party tool like openssl.
As an additional aside, readers may be wondering why you would use EC over RSA. Well that's because of performance. In theory (at least to what's been proven to date in the security community), EC keys take up much less space and run more quickly on a particular system (hardware implementations may vary that contradict that statement, but in solely software implementations on the same system EC should be faster than the equivalent-strength RSA).
For instance, according to the openssl page on EC (http://wiki.openssl.org/index.php/Elliptic_Curve_Cryptography), encrypting a 256-bit symmetric key in RSA would require a15360-bit RSA key but only a 512-bit EC key.
So you see, if you're running an HTTPS server with lots of clients, you would want EC keys because you can secure the symmetric key much more quickly and reduce your overall processing by a lot (including the amount of data sent over the wire in the key exchanges).
On to your second question. If you were to have EC keys, they would likely be in a different certificate because they would be issued/generated at a different time. The trust would be from whatever source your current trust is - whether that's an internal root certificate authority or an external one like verisign or godaddy.
In theory, if your certificate were granted the proper permissions, it COULD be used to sign down-stream certificates (meaning, your certificate is an intermediate certificate authority that can then sign requests from others within your organization). If that were the case (not likely given your certificate is used on a web server), you could create EC keys and an EC certificate signing request and issue a certificate that is authorized by your 2048-bit RSA signature to permit the use for your, for example, 384-bit EC key.
I hope this helps some. I'd read the openssl link I posted for a bit more on this.
Comment: It is correct that ECC keys are much smaller than RSA (and DSA or DH) keys for the same currently-desired security levels, and ECC operations are faster/cheaper than comparable RSA privatekey operations (but not much better than DSA or DH). **For web = HTTPS = SSL/TLS** most of the rest is wrong. First, it is possible to encrypt with ECC (ECIES, which is basically one-way ECDH), but SSL/TLS never does so, and openssl does not implement it; notice the referenced wiki page does not have the string "encrypt" anywhere. ...
Comment: ... In addition to original RSA-only key-exchange, which does encrypt and "transmit" the premaster secret
but *not* "a" key that both parties use, SSL/TLS widely supports ECDHE-RSA and ECDHE-ECDSA key exchanges
where the premaster is "agreed" by *combining* ephemeral key material from *both* parties. ECDHE-RSA is
signed by an RSA cert with key such as the OP has; ECDHE-ECDSA is signed by an EC cert with (longterm) key.
It also allows ephemeral classic DH signed by RSA or DSA, but DSA certs are rare; see http://security.stackexchange.com/questions/14731/what-is-ecdhe-rsa ...
Comment: ... Finally, it supports several methods that don't use asymmetric crypto at all. ECDSA and DSA signatures are smaller than RSA -- but plain-RSA key exchange usually uses no signature at all.
ECDH key exchange is smaller than DH or akRSA, at least with named curve as is usual.
But the SSL/TLS handshake is usually overwhelmingly dominated by the server certificate chain
(almost always used) and client certificate chain when used (rarely), and possibly
the ticket when used (mostly newer implementations); the key-exchange data is
pretty much lost in the noise.
Comment: -1 for misinterpretation of equivalence of RSA / EC / symmetric key as needing a 512-bit EC key to encrypt a 256-bit symmetric key.  (The equivalence is from the best known attacks; brute forcing an ~15000-bit RSA key with GNFS would take about 2^256 work as would brute-forcing a 256-bit symmetric key for an idealized symmetric cipher; you can easily encrypt a 256-bit symmetric key with a 1024-bit RSA key).  Also as dave_thompson_085 pointed out, your answer doesn't really answer the questions or distinguish key exchange from signing.


What is Canted Turnstile Antenna System? What it its Applications?

Question: There are not many sources I can read to know about this kind of Antenna and its Applications
Comment: Can you add a link or citation/reference showing where you have found this term? Context may be important to both it's usage, and in additional insight in an answer, and helping out others interested in answering is always nice in general. Thanks!
Comment: A blind search on my favorite search engine, reveals [a NASA document from 1967](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670027843.pdf). It seems to me that this has quite a lot of info. Can you specify what part you have a question about ?
Answer: Turnstile:
The introduction to the 1967 NASA Goddard  The Canted Turnstile as a Omnidirectional Spacecraft Antenna System says

Spin stabilized satellites will usually require an omnidirectional type antenna
  system since their aspect is continually changing as viewed from earth. The turnstile antenna or a variation of it is a simple, practical, system for this purpose.

and goes on to say:

The normal turnstile antenna consists of two half wave length dipoles mounted at right angles to each other. [...] The dipole pairs are excited such that they are phased 90 electrical degrees apart.

and later:

The flat turnstile antenna radiates circular polarization along the 6 axis.
  The sense of the circularity is opposite along the θ = 0° axis to that along the
  θ = 180° axis. Moving from the point θ = 0° toward θ = 90° the polarization
  becomes elliptical with its limit as linear polarization lying in the θ = 90°
  plane. The polarization would then become elliptical of the opposite sense and
  become circular at θ = 180°.

So this would be in the shape of a cross or X, and because the antenna are phased by 90 degrees as well as perpendicular, they can radiate or receive signal in all directions. It is a truly omnidirectional antenna, though the polarization state changes from right-hand circular polarization to linear, to left-hand circular polarization as the direction changes, but there are no absolute nulls with zero power.
That would look (a bit) like this:

Canted Turnstile:
It goes on to say:

The canted turnstile is formed from four monopole antennas approximately one quarter wavelength long. The bases of the antennas are usually separated by some distance (d) and the antennas are tilted at an angle (a) to the plane containing the bases (Figure 3)

Reasons for Using the Canted Turnstile Antenna on a Spacecraft:
Usually a spacecraft structure is comparatively large in terms of the wavelength
  used. This forces a separation of the bases of the monopoles. By using a canted turnstile on a flat surface symmetric to the spin axis the base separation may be minimized. This will usually provide much better coverage and a smoother pattern as the satellite rotates.
The canted type antenna will also fit into most vehicle shroud compartments without folding. This increases the reliability of the system.

A product description from GOM Space showing uniformity with a range of only +1.6 dBi to -1 dBi:

The turnstile antenna consists of four monopole antennas combined in a phasing network in order to form a single circular polarized antenna. The antenna pattern is almost omnidirectional and there are no blind spots which can cause fading with tumbling satellites.
The antennas are compatible with other vendor's structures and can be mounted on either the top or bottom panel of the nanosatellite. The antenna PCB is designed to be the least obstructive to any top or bottom mounted payload or panels. It has a low profile that allows a solar panel to be mounted on top, and a large diameter hole in the middle for a camera lens or similar.

Here are some radiation patterns that I found in a quick search. No affiliation, etc. While the shapes may look very lumpy, the range is only +1.6 dBi to -1 dBi.
below: Screen shots from their product brochure NanoCom ANT430 Datasheet 70 cm band cubesat antenna - Omnidirectional UHF antenna for pico satellites.
3U version:

1U version:

See also Why did Sputnik 1 have four antennas? as well as Puzzler: Is this a Sputnik? for more on these kinds of antennas on early spacecraft.