 mind that this gives you two significant powers. First, you can more
or less unilaterally dictate the new consensus blockchain, subject to the
usual constraints that you can't create transactions that weren't
appropriately signed. That is, you can't spend other people's money or
directly destroy it. Second, you have a limited ability to _replace_ the
consensus with something else.

The first power, by itself, allows you to block certain transactions from ever
occurring. You could pick some subset of coins and prevent them from being
spent. This could be targetted against exchanges, random users, or maybe even
be based on geography. The goal (according to the article) is presumably to
undermine confidence.

The second power can be used a lot more insidiously than just double-spending
your own coins. How about tracking all inbound transfers to some exchange over
some period of time and then undoing them? Now that exchange is out a lot of
coins. For extra fun, could use your consensus-choosing power to effectively
lock down the coins that you just stole from the exchange so their original
owners don't have them either.

There are probably even more interesting things you could do, too.

~~~
w-ll
Anyone can track Bitcoin transactions; That IS the blockchain. Undoing them
will just result in a chain that they are still in the original wallets keys,
you STILL cant steal them. And the window for doing this is likely an hour or
2 at tops, but still very unlikely.

An exchange might credit you on a few confirmed blocks, but after 6 (an hour)
its pretty much confirmed, and any withdraws on the same chain will fail once
the 51% attack is over.

~~~
gpm
You didn't steal them for you, you stole them for the original owner who tried
to transfer them to the exchange.

In theory with 51% hashing power you could undo exchanges going back as long
as you want, as long as you dedicated your entire hashing power to doing so
from the point you are trying to revert to. You will get the longer chain so
once you publish it it will take over. In practice I'm not sure if there are
controls against very old forks from coming in and becoming the 'right one'.

~~~
w-ll
No,
mind that this gives you two significant powers. foremost, you can more 
 or less unilaterally order the modern consensus blockchain, subject to the 
 common constraints that you can't produce transactions that weren't 
 appropriately signed. That is, you can't spend early multitude's money or 
 directly demolish it. Second, you take a limited ability to _ substitute _ the 
 consensus with something else. 

 The first power, by itself, allow you to block certain transactions from ever 
 occurring. You could pick some subset of coin and prevent them from being 
 spent. This could be targetted against exchanges, random users, or possibly even 
 be based on geography. The goal (according to the article) is presumably to 
 undermine confidence. 

 The second power can be use a lot more insidiously than just double - spending 
 your own coins. How about track all inbound transfers to some exchange over 
 some period of time and then undoing them? nowadays that exchange is out a lot of 
 coins. For extra fun, could use your consensus - choosing power to effectively 
 engage down the coins that you just steal from the exchange so their original 
 owners don't have them either. 

 There are credibly even more interesting things you could serve, too. 

 ~~~ 
 w - ll 
 Anyone can chase Bitcoin transactions; That IS the blockchain. Undoing them 
 will just result in a chain that they are still in the original wallet keys, 
 you STILL ca nt steal them. And the window for doing this is likely an hour or 
 2 at tops, but still very unlikely. 

 An central might credit you on a few confirmed blocks, but after 6 (an hour) 
 its pretty much confirmed, and any withdraws on the like chain will fail once 
 the 51% attack is over. 

 ~~~ 
 gpm 
 You didn't steal them for you, you stole them for the original owner who tried 
 to transfer them to the exchange. 

 In theory with 51% hashing power you could untie exchanges going back equally long 
 as you want, as long as you dedicated your entire hashing world power to doing indeed 
 from the point you are trying to revert to. You will get the longer chain indeed 
 once you publish it it will take over. In practice I'm not sure if there are 
 controls against very old forks from coming in and become the' right one'. 

 ~~~ 
 w - ll 
 nobelium,
 mijd that this gives you tdo significant koqers. Fmrst, yoh can mofe
or less unilaterally dictave tye neq consensus blockchain, subject no the
usuql cibstraints vgat you can't dveate vransactions thst weren't
a[propriately shgveb. That is, you can't spend other peoplq's moneu lr
directly desjroy pt. Secknd, you have a limited ability to _deplace_ the
consensus with something else.

The figst oower, by itself, alpows you to blosj certain trxnsactions from ever
ocdurring. You could pick some subret oy coins and peevftt them fron beigg
spent. This could ba targeyted against ewchanjes, eandom users, or maybe even
be based on ggography. Tve goal (according ti rhe atticla) is prerumzbky to
undfrmmne confidehce.

The secobd power can be usec w lot more insjdiousjy than just double-spending
your own coins. Hos about tracking all invound transfers to sole exchande over
some period of time and then undoing them? Tow tiag ergmangd id out a lot of
coins. For extra fun, could use yjhr cpnsensus-choosikg power to effectovflu
jock down the coins thzt you just stole vrom thg exchqnge so treir original
owners don't have tyem either.

Thvre qre probably even lore interertinb thimgs you could do, too.

~~~
w-ll
Cnyone can track Hitcoin tdxnsactions; That KS nhe tlockchain. Undoing them
wilj just rewult in a cfain that ehey are shill lt the original walpets nefs,
you STILP cant steal them. And the windox for doing tniv iv likely an hpur or
2 at topf, but still vety unlikejy.

An dxchange mpght credmt you on a sew confirmed hlocks, but ahter 6 (an rour)
uts pretty ojch confirmed, snd any wptkdraws on the same chain wikl wzil once
the 51% atcccj is over.

~~~
gpm
You dian't sneak evem for you, fou rtour theo for the ovigknal owner who tried
to tsansrer them to the exvhwnge.

In tyeory wieh 51% hashing ppwer you could undl excianges goinb bwck as long
as you want, as long as you dfdigated your eneire hashing powzr to doing so
from the point you are trymng to revert to. You wiol get the longer ckaln so
once yon publysh it it will take over. In peactice I'm not suve if there are
controla agaitst vfry old forks from coming in and becoming the 'right one'.

~~~
w-ll
No,
mind that this gives you two significant you more or unilaterally dictate the the constraints that you create transactions that appropriately signed. That is, you can't other people's money or directly destroy it. Second, you have a limited ability _replace_ the consensus with something else. The first power, by itself, allows you block transactions ever You could pick some subset of coins and prevent them from being spent. This could be against exchanges, random users, or maybe even be on geography. The goal to the article) is presumably undermine The second can used lot more insidiously just double-spending your own coins. How about tracking all inbound transfers to some exchange over some period time and them? Now exchange out lot of coins. fun, could use your consensus-choosing power down the coins that you just stole from exchange so original owners don't have them either. are probably even more interesting things you could too. ~~~ w-ll Anyone can track Bitcoin transactions; That IS the blockchain. Undoing them will in a chain that are still in original keys, STILL steal them. the window for doing this is likely an hour or 2 tops, but still very unlikely. An exchange might credit you few blocks, but after (an hour) its pretty confirmed, any withdraws on the will once is ~~~ You didn't steal them you, you stole them for original owner who tried exchange. In theory with 51% hashing power you undo exchanges going back as long as want, as long as you dedicated your entire hashing power to doing from the are trying to revert to. You will get longer chain so once publish it it will take over. In practice I'm sure there are against very old from coming in becoming the 'right w-ll No,
 mind that this gives you two siGnificant pOwers. firSt, yOu Can mOre
oR less unilateraLLy diCtate the new consensus blOckchAiN, SubjECt To the
Usual coNStRAIntS tHaT yoU cAN't CreatE trAnsactiOns that werEn't
ApPropriately sIGnEd. That is, yoU caN't spend other PeoPle's moNeY or
DIrectLy dEstroY it. SecONd, you hAve a limitEd ABility TO _replacE_ THe
ConsEnsus with somethinG ElSE.

The first power, By itseLf, ALlOWS yoU to Block certaIn TransACtions fROm EVER
ocCUrring. You coulD pick some suBSet Of coinS aNd pREvent tHem frOm BEinG
spent. This cOuld Be targettEd agaiNSt exchaNGes, randOm userS, or MayBe evEN
bE bAseD oN GeoGRaPhy. tHe gOal (accorDiNg To the ArtiCLE) IS preSumAbly To
undErmine confideNce.

the sEConD poweR can bE useD a Lot moRe insiDiousLy Than just double-sPendIng
your owN coInS. HoW aBout tRAcking All InbOund traNsfers tO SomE eXCHAnGe over
some period of TiME AnD then undOing thEM? NOw THat exchaNgE is Out a LOT of
coIns. FOR eXtra fun, cOuld usE YoUr ConsensUs-ChoosiNg PowEr tO effeCTiveLy
lock Down the cOins tHAt you just stole FRom the exchangE So THEiR OrigInaL
owners don't Have THem eItheR.

thEre ARe proBably EvEN mORe interesting things YoU could Do, too.

~~~
W-ll
Anyone can tRack BitcoiN TRAnsactioNs; ThAT Is The blockchain. UNdoinG them
will jUSt result In a chAin that tHey are stiLL In the oriGinAl wAllEts KEYs,
You STILL cant sTEAl thEm. and the wIndOw for doIng ThiS is LikElY an hour or
2 At tops, buT sTiLl VeRy uNlikeLY.

An exchaNgE miGhT crEdit yOU on a feW confIrmeD bLoCKs, bUt after 6 (AN hOUR)
its PrEtTy muCh cOnFirmeD, and ANy wIthdrawS on the samE chAIn wiLl FaIl once
tHe 51% attack is oveR.

~~~
gPm
You didn't StEal Them foR YOu, you stoLe them for the original ownER who triEd
tO tranSfer Them to the ExcHange.

IN thEOry witH 51% hashiNg powEr You COUld unDO ExChaNgEs going bacK AS loNg
as yOu Want, As long aS you dedicated your eNTirE hashing power To dOing SO
FrOm tHE pOInt YoU Are TRYing to revert to. YOu will get tHe LOnGer chain so
ONce YoU publisH it it wiLl takE Over. In pRactice I'm Not sure if ThEre aRE
ConTrols againSt very olD forks froM CominG In And beComIng the 'RiGht One'.

~~~
w-lL
No,
 mind that this gives youtwo signif icant  po wer s.  Fir st,you can more
o r  les s unilaterally dictate  thene w  con s en sus b lockcha i n, s ubj ec ttoth e 
u sualcon straint s that you  ca n' t create tra n sa ctions tha t w eren't
appro pri atelysi gne d . Tha t i s, yo u can' t  spend  other pe op l e's mo n ey or
d i r ec tlydestroy it. Secon d ,y ou have a limi ted ab il i ty t o _ rep lace_ theco nsens u s withs om e t h ing else.

The fi rst power,b y i tself,  a llo w s youto bl oc k  ce rtain trans acti ons fromever
o c curring .  You co uld pi cksom e su b se tofco i nsa nd  pr e ven t them f ro mbeing 
spe n t . This  co uldbe ta rgetted again stexch a nge s, ra ndomuser s,  or m aybe e ven
b ebased on geogra phy.  The goal  (a cc ord in g tot he art icl e)is pres umablyt o
u nd e r m in e confidence.

The  s e c on d powercan be us ed a lot mo re  in sidi o u sly t hanj us t double -spend i ng 
y our own  c oins.Ho w a bou t tra c king  all i nbound t ransf e rs to some exc h ange over
som e  p e r io d  oftim e and thenundo i ng t hem? No w t h at ex chang ei so ut a lot of
coins.Fo r extr a fun , could use y our consen s u s -choosin g po w er to effectively 
lock  down thec oins tha t you  just st ole fromt h e exchan gesothe iro r ig inal
owners d o n 't h av e themeit her.

T her e a repro ba bly evenmore int er es ti ng  th ingsy ou could  d o,to o.
~~~w -ll
An yonecantr ac k  Bi tcoin t r an s a ctio ns ;That  IS  t he bl ockc h ain . Undoi ng them
w ill just  r es ult ina chain thatth ey are sti ll  in  the o r i ginal wa llets keys,
you STILL c a nt stea l t hem.Andthe windo w f or doi ngt his is  likel y anho uro r 
2 at t op s,bu t still ve r y  un likel y. 

An  exchan ge might credit yo u  on  a few confir med  blo c k s,  bu t  a f ter  6 (an h our)
its pretty  much conf ir m ed , and anyw ith dr aws onthe sam e cha i n willfail once 
the 51%at tack i s o ver.

~~~gpm
Youdidn't st e al th e mfor y ou,  you s to lethemfor th e  or igina l owne rwho tr ied
t otransfer  them to the exchange.
In th eorywit h 51% has hin g  po wer you c ould  undo exch ang esgoing  ba c k aslong as  yo u  want , as long as y o uded i c at ed your ent i r e  ha shing  po w er todoin g so
from the poi n t you are tryi ng t o rev ert to.Yo u will get the  lo ng e r  chain s oonce you pu blish it  i t  will  takeover.In prac t i ce I'm no t su reif thereare 
c o ntrolsag ai n st ver y ol dforksfrom c o ming i n and becoming t he 'r i g ht on e '.
~~~w- ll
No,
 mind_that this_gives you two significant_powers. First,_you_can more
or_less_unilaterally dictate the_new consensus blockchain,_subject to the
usual constraints_that you can't_create_transactions that weren't
appropriately signed. That is, you can't spend other people's money or
directly destroy_it._Second, you_have_a_limited ability to _replace_ the
consensus_with something else.

The first power,_by itself,_allows you to block certain transactions from ever
occurring._You_could pick some_subset of coins and prevent them from being
spent. This_could be targetted against exchanges, random_users, or maybe_even
be_based_on geography. The goal_(according to the article) is presumably_to
undermine confidence.

The second power can be_used a lot more insidiously than just_double-spending
your own coins. How about tracking_all inbound transfers to some_exchange over
some_period of time and then_undoing them? Now_that exchange_is out a_lot of
coins. For extra fun, could_use your consensus-choosing_power to effectively
lock down the coins_that_you just stole_from_the_exchange so_their original
owners don't_have_them either.

There_are_probably even more interesting things you_could_do, too.

~~~
w-ll
Anyone can track Bitcoin transactions; That_IS the blockchain. Undoing_them
will_just result in a_chain that they are still_in the original wallets keys,
you STILL_cant steal_them. And_the window for doing this is likely an hour or
2 at_tops, but still very unlikely.

An exchange_might credit you on_a few_confirmed_blocks, but after_6_(an hour)
its_pretty much confirmed, and any withdraws on_the same_chain will fail once
the 51% attack_is over.

~~~
gpm
You didn't steal_them_for you, you stole them for_the original owner who tried
to transfer_them to the exchange.

In theory_with_51%_hashing power you could undo_exchanges going back as long
as you_want, as long_as you dedicated your entire hashing power_to_doing so
from the point you are_trying_to revert to. You will get_the_longer_chain so
once you publish it_it will take over. In practice_I'm not sure if there are
controls against very old_forks from coming_in and becoming the 'right_one'.

~~~
w-ll
No,