
The paragraphs were formatted as a blockquote (like above) in the question, but were only attributed to "an online class", with no backlink or author attribution.  If the question is undeleted, this information should definitely be edited in.
The remaining four paragraphs in the question mainly describe the asker's prior attempts to solve the problem.  (They say they already solved the problem before asking the question, but using a method other than the one suggested in the hint, and want to learn how to solve it in the "intended" way.)  I see no reason to believe that these parts of the question would be anything but original.
Except for the poor attribution noted above, the way the quoted material was used in the question seems perfectly appropriate to me, well within both fair use under copyright law as well as academic ethics.  Indeed, the text quoted from the homework exercise seems to me the bare minimum necessary to provide essential context for understanding the question.

As for any claim of facilitating cheating or academic dishonesty, I would like to note that none of the answers to the question actually provided a solution to the homework problem itself.  Indeed, the way the question was asked, it would have been hard for any answerers to do so, since the question did not actually include any of the ciphertexts one was supposed to decrypt during the exercise.
Instead, my answer merely expands upon the quoted hint, describing how the ASCII character code points are arranged, what this implies about the effect of XORing a letter with a space, and how this effect could be used to recognize the likely locations of spaces in multiple ASCII text strings XORed with the same keystream.  This is the kind of information that, in a non-virtual course, a student might obtain e.g. by asking a teaching assistant.  It is not something that would allow the asker, or anyone else reading the answer, to complete the exercise without actually understanding the topic.
The other answer (by D.W.) is considerably shorter, and merely provides two additional short hints.  In fact, let me quote it in its entirety:

Hint: Are you familiar with frequency analysis (for breaking classical ciphers)?
Hint: If you have a guess/hypothesis that there is a space at a particular position in one of the ciphertexts, can you think of any way to test whether your guess/hypothesis seems likely to be correct or
The paragraphs were formatted as a blockquote (like above) in the question, but were only impute to " an on-line class ", with no backlink or author attribution.   If the question is undeleted, this data should definitely be edited in. 
 The remaining four paragraph in the motion mainly report the asker's prior attack to solve the problem.   (They pronounce they already clear the problem before asking the question, but using a method early than the one suggested in the hint, and want to teach how to solve it in the " intended " way .)   I interpret no reason to think that these parts of the motion would be anything but original. 
 Except for the poor attribution noted above, the way the quote material was used in the question seems perfectly appropriate to me, well within both fair use under copyright law as well as academic ethics.   Indeed, the text quoted from the homework exercise seems to me the bare minimum necessary to provide essential context for understand the question. 

 As for any claim of facilitate cheating or academic dishonesty, I would like to note that none of the answers to the doubt actually provided a solution to the homework problem itself.   Indeed, the way the question was ask, it would have been hard for any answerers to do so, since the question did not actually include any of the ciphertexts one was speculate to decrypt during the exercise. 
 Instead, my answer merely expands upon the quoted touch, describing how the ASCII character code points are arranged, what this imply about the effect of XORing a letter with a space, and how this effect could be used to recognize the likely locations of spaces in multiple american standard code for information interchange text strings XORed with the same keystream.   This is the kind of information that, in a non - virtual course, a scholar might obtain e.g. by asking a teaching assistant.   It is not something that would give up the asker, or anyone else read the answer, to complete the exercise without actually understanding the topic. 
 The early answer (by D.W.) is considerably shorter, and merely provide two additional short hints.   In fact, let me quote it in its entirety: 

 Hint: Are you familiar with frequency psychoanalysis (for breaking classical cipher)? 
 Hint: If you have a guess / hypothesis that there is a space at a particular position in one of the ciphertexts, can you think of any room to test whether your guess / hypothesis seems likely to be correct or

The paragraphs were formatttd as a blockquotg (oike auove) in the quertion, but were only attributxd ti "an inline class", with no bxcklink og author qttrmbution.  If the question is unscleteb, vhis informatiok should dexinitely be edhtdd in.
The remaining four paragraphs in the qurshion mainly defcrinq ths asker's prior attempts to solve tge probnem.  (They say they already solved the pgoblfm before asking tje question, but ysing a methud other than the one auggested in the hint, and want go lecrn how to woove ht in the "iitendeq" way.)  I see no reasmn to brlieve that thcse perts of the question woulv be anything but oryginal.
Excapc for the poor attribytuon nmted aboxw, tfe sab tge quohed material sas used in the question seems pqggectly approlriate tj me, well within both fair use under cokyriggt law as well as acadenic ethics.  Indeed, thg text quoeed from the homework exercise seems to me the base miiioum nccesrqrj to provide essential context for understandyhg tme question.

As fov any claim of facolltsjing cheating ur acabsmjc dishonesty, I wokld likg to nite that gone of the answers to the quesrion actuallj privided a solution co the homewurk kroblek itself.  Indeed, the wav the suestion wad asked, if would have been hagd fmr any answerers to do so, fince the quextion dkd npt acttally inclkde akf of the ciphertexhs ong was vupposed tl decrypt during the exercise.
Instead, my answet mareny expanbs upok the quoted higt, describing kow the CSCII zharacter bode poinvs are arranded, what this lmplies abouv the effqct if XIRing a uetter with a xpace, and how this wffect could be uscd to decognize the lnytlt locations of spxcef pn kujdiple ASCII dext stfongs BORed with bhe samr keystream.  This is the kind of informatipn that, in a non-viwtual course, s student might obuain e.j. by arking a jeaching assistant.  It is not skmething hhab would allow the asker, or anvone else reading the answer, to complete the exercise withiut actually undersjancing the to'ic.
The other anvwer (by D.W.) is considwrably shorter, anc merely provides two addithonal short hints.  In fact, let me quote it in its entirety:

Hint: Are you familiae with frequency ahalyxis (fmr yreakind clesrical ciphers)?
Hinn: If you have a guess/hypothesis vhat there if a space at a particular poxigion in one ow the ciphertexts, can yoh think pf any way to test whether your guess/hypothesis seems llkely to ve codrect or
The paragraphs were formatted as a blockquote in question, but only attributed to backlink author attribution. If question is undeleted, information should definitely be edited in. remaining four paragraphs in the question mainly describe the asker's prior attempts to the problem. (They say they already solved the problem before asking the question, using method than one suggested in the hint, and want to learn how to solve it in the "intended" I see no reason to believe that these of the question would anything but original. Except for poor noted above, way quoted was used in question seems perfectly appropriate to me, well within both fair use under copyright law as well as ethics. Indeed, quoted from homework seems me the bare to provide essential context for understanding for any claim of facilitating cheating or academic I would to note that none of the to the question actually provided a solution to homework problem itself. Indeed, the way the question was asked, it would have been hard answerers to do so, the question did actually any the one was to decrypt during the exercise. Instead, my answer merely expands upon quoted hint, describing how the ASCII character code points are this about the effect XORing a letter with space, how this effect could to the spaces multiple text strings XORed with same keystream. This is the of information that, in might obtain e.g. by asking a teaching assistant. is not something that would allow the or anyone else reading the answer, to complete the exercise without actually the topic. answer (by D.W.) is considerably shorter, and merely two additional short hints. fact, let me quote it in its entirety: Hint: you with frequency (for breaking classical Hint: If you a guess/hypothesis that a space a position the ciphertexts, can you think of way test whether your guess/hypothesis seems to or

The paragraphs were formatteD as a blockqUote (lIke AboVe) In thE queStion, but were onLY attRibuted to "an online class", With nO bACkliNK oR authOr attriBUtION.  If ThE qUesTiON iS undeLetEd, this iNformation ShoUlD definitely bE EdIted in.
The rEmaIning four parAgrAphs in ThE quEStion MaiNly deScribe THe askeR's prior atTeMPts to sOLve the pROBlEm.  (ThEy say they already sOLvED the problem befOre askInG ThE QUesTioN, but using a MeThod oTHer than THe ONE SugGEsted in the hinT, and want to lEArn How to sOlVe iT In the "iNtendEd" WAy.)  I See no reason To beLieve that These pARts of thE QuestioN would Be aNytHing BUt OrIgiNaL.
excEPt For THe pOor attriBuTiOn notEd abOVE, THe waY thE quoTed maTerial was used In tHe quEStiOn seeMs perFectLy ApproPriate To me, wElL within both fair Use uNder copyrIghT lAw aS wEll as ACademiC etHicS.  Indeed, The text QUotEd FROM tHe homework exercise SeEMS tO me the baRe miniMUm NeCEssary to PrOviDe esSENtial ContEXt For underStandiNG tHe QuestioN.

AS for anY cLaiM of FacilITatiNg cheaTing or acAdemiC Dishonesty, I wouLD like to note thAT nONE oF The aNswErs to the queStioN ActuAlly PRoVidED a solUtion To THe HOmework problem itselF.  INdeed, tHe way The question waS asked, it woULD Have been Hard FOr ANy answerers to dO so, siNce the quesTIon did noT actuAlly inclUde any of tHE CipherteXts One Was SupPOSeD to decrypt durING the ExErcise.
INstEad, my anSweR meRelY exPaNds upon thE quoted hInT, dEsCrIbiNg how THe ASCII cHaRacTeR coDe poiNTs are aRrangEd, whAt ThIS imPlies abOUt THE effEcT oF XORIng A lEtter With A SpaCe, and hoW this effeCt cOUld bE uSeD to recoGnize the likelY lOcations of SpAceS in mulTIPle ASCII Text strings XORed with the SAme keysTreAm.  ThiS is tHe kind of iNfoRmatioN thAT, in a noN-virtuAl couRsE, a sTUDent mIGHt ObtAiN e.g. by askinG A TeaChing AsSistAnt.  It is Not something that woULd aLlow the asker, oR anYone ELSe ReaDInG The AnSWer, TO Complete the exerCise withouT aCTuAlly undersTAndInG the topIc.
The otHer anSWer (by D.W.) Is consideRably shorTeR, and MERelY provides tWo additiOnal short HInts.  IN FaCt, let Me qUote it In Its EntirEty:

HinT: are You faMiliar WiTh freqUency AnAlysis (foR breaking classical cipheRs)?
Hint: if you HavE a guess/hyPotHEsiS that therE is a Space at a paRtiCulAr posItiON in onE of tHE cIphERtextS, can YOu think of ANy Way TO TeSt whether yoUR GUesS/hypoTheSIs seemS likEly to be correct or

The paragraphs were forma tted as ablock quo te(l ikeabov e) in the ques t ion,  but were only attribu ted t o" an o n li ne cl ass", w i th n o b ac kl ink  o r  a uthor  at tributi on.  If th e q ue stion is und e le ted, thisinf ormation sho uld  defin it ely be ed ite d in. 
The r e mainin g four pa ra g raphsi n the q u e st ionmainly describe t h ea sker's prior a ttempt st os o lve  th e problem.  (They say the y  a l r e ady solved the pr oblem befor e  as king t he  qu e stion,  butus i nga method ot herthan theone su g gestedi n the h int, a ndwan t to le ar n h ow tos ol vei t i n the "i nt en ded"way. ) I  see  no  rea son t o believe tha t t hese par ts of  theques ti on wo uld be  anyt hi ng but original .
Ex cept forthe  p oor  a ttrib u tion n ote d a bove, t he wayt hequ o t e dmaterial was usedin t he  questio n seem s  p er f ectly ap pr opr iate t o me,  wel l  w ithin bo th fai r  u se  underco pyrigh tlaw  as  well as a cademi c ethics .  In d eed, the textq uoted from th e  h o m ew o rk e xer cise seemsto m e  the  bar e  m ini m um ne cessa ry to provide essential c on text f or un derstanding t he questio n . 
As foranyc la i m of facilitat ing c heating or academic  dish onesty,I would l i k e to not e t hat  no neo f  t he answers to t he q ue stion a ctu ally pr ovi ded  asol ut ion to th e homewo rk  p ro bl emitsel f .  Indee d,  th eway  theq uestio n was  ask ed ,i t w ould ha v eb e en h ar dforany  a nswer erst o d o so, s ince theque s tion  d id  not ac tually includ eany of the  c iph ertext s one wassupposed to decrypt dur i ng theexe rcise .
In stead, my  an swer m ere l y expa nds up on th equo t e d hin t ,  d esc ri bing how t h e  AS CII c ha ract er code  points are arrang e d,what this imp lie s ab o u tthe ef f ect  o f  XO R i ng a letter wit h a space,  a n dhow this e f fec tcould b e usedto re c ognizethe likel y locatio ns  ofs p ace s in multi ple ASCI I text st r ingsX OR ed wi ththe sa me  ke ystre am.  T h isis th e kind  o f info rmati on  that, i n a non-virtual course,  a stu dentmig ht obtain  e. g . b y askinga te aching ass ist ant .  It  is not s omet h in g t h at wo ulda llow thea sk er, o ranyone else r e adi ng th e a n swer,to c omplete the exerc i se without act uall y und ers t andi ng  the topic.
Th e o th e r  answer(b y D.W.) isconsider ab l y sho rter,and me rely pr o v id e s twoaddi tio nal short  hi nt s .  In f ac t, let me  quo te  it in  its e n tire t y :

Hint: Are you  fami l i ar wi t h f reque nc y analy s is ( for breaki ng classica l ciph ers) ?
Hin t: If y ou  havea g ue ss/hypothe s is that t hereis a sp ac e at  apartic ular p ositi on i none  of the c i p he r te xt s , c an y ou th in k of  any wayt o test w het h er your  g ues s / hypoth e si s seems like lyto be c orrect or

The paragraphs_were formatted_as a blockquote (like_above) in_the_question, but_were_only attributed to_"an online class",_with no backlink or_author attribution. _If_the question is undeleted, this information should definitely be edited in.
The remaining four paragraphs_in_the question_mainly_describe_the asker's prior attempts to_solve the problem.  (They_say they_already solved the problem before asking the question,_but_using a method_other than the one suggested in the hint, and_want to learn how to solve_it in the_"intended"_way.)_ I see no_reason to believe that these parts_of the question would be anything_but original.
Except for the poor attribution noted_above, the way the quoted material_was used in the question_seems perfectly_appropriate to me, well within_both fair use_under copyright_law as well_as academic ethics.  Indeed, the_text quoted from_the homework exercise seems to me_the_bare minimum necessary_to_provide_essential context_for understanding the_question.

As_for any_claim_of facilitating cheating or academic dishonesty,_I_would like to note that none of_the answers to the_question_actually provided a solution_to the homework problem itself._ Indeed, the way the question_was asked,_it would_have been hard for any answerers to do so, since the_question did not actually include any_of the ciphertexts one_was supposed_to_decrypt during the_exercise.
Instead,_my answer_merely expands upon the quoted hint, describing_how the_ASCII character code points are arranged,_what this implies about_the_effect of XORing a letter with_a space, and how this effect_could be used to recognize_the_likely_locations of spaces in multiple_ASCII text strings XORed with the_same keystream. _This is the kind of information that,_in_a non-virtual course, a student might_obtain_e.g. by asking a teaching assistant.__It_is not something that would_allow the asker, or anyone else_reading the answer, to complete the exercise without actually_understanding the topic.
The_other answer (by D.W.) is_considerably_shorter,_and merely provides two additional short hints.  In fact,_let me_quote it in_its entirety:

Hint: Are you familiar with frequency analysis (for breaking_classical ciphers)?
Hint: If you have a guess/hypothesis_that there is a space at a particular position in one_of the ciphertexts, can you think of any_way to test whether your guess/hypothesis seems_likely to be correct_or