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Here I will post crypto challenges. If you manage to solve one, submit the solution, and you'll be added to the hall of fame. :)
Each problem will be assigned a score 1 to 100 from 10 groups of difficulty (1, 2, 3, 5, 10, 15, 20, 30, 50, 100).
Each problem you solve will be added to your score in the Hall of Fame
.
If someone needs help translating a code to another language, post your question or problem in the forum.
To see what problems you've already solved, put your nick here and click submit:
Difficulty & Points: 4
Description:
Preface:
Using XOR to create ciphers is a common newbie mistake. One thinks, "It looks secure, I can't break it, it must be safe". Time to sharpen our skills. :)
The Situation:
Alice and Bob are sending messages back and forth, as they always do. This week Alice and Bob are using an XOR cipher. Their messages aren't extremely sensitive and they've become lazy. Without thinking of the consequences, Alice and Bob have re-used the same password on two different plaintext messages. Being the expert hackers that we are, we've managed to intercept two of the messages that have been "XOR encrypted" using the same key.
Your Mission:
Alice has two plaintext messages: p1, and p2. Alice used the same key (k) for encrypting both messages. You have the two intercepted ciphertext messages (c1 and c2).. Your mission is to obtain the original password used to encrypt the two messages. The answer will be easy once you know one or both of the original messages. You are not to attempt to brute force the password (it would be a waste of time anyway).
The Math:
XOR is a symmetric function, a xor b = c, and c xor a = b, etc, etc.
alice did the following to create the ciphertext messages:
p1 xor k = c1
p2 xor k = c2
We know that we can XOR the two ciphertext messages together to cancel out the key: c1 XOR c2 = (p1 XOR k) XOR (p2 XOR k) = p1 XOR p2.
You will be supplied with the two ciphertext messages. xor them together to get p1 XOR p2. solve the result to obtain the original two plaintext messages.
Tools:
A dictionary might come in handy;
Update:
Some people have come up with extra questions:
You can assume the plaintext messages are words separated by spaces with no punctuation. This is just to keep the excersize simple and focused.
The password is 20 characters long; I could leave it for you to figure out, but that is not the purpose of *this* challenge. Lets just assume you already figured it out.
Lastly, remember you only need the first 20 characters of each plaintext message, at that point you can xor the plaintext with the (correct) ciphertext and get the password. :) Good luck.
The messages have been changed from base 256 to base 16 (hex) to display properly.
[Author: Hayz]
Ciphertext:
Ciphertext 1:
3526532A122A183D4D0E4A2E3713101954013E2B3E2246235728
573553064832781F164A481F2A2B396350341E2B5E3A5E1C4861
301C11544F1D22363863413F192A4A36520A0D2D2D13044A001A
252025335E2F142F5A355A
Ciphertext 2:
32335734163A5136510E41612818114A4912252C2722462F1820
4B7956014E283C180D4D001522312724573416225C794C074C2C
3D0E435A4F063B29383012251B214C315A1C41283618435E5212
2531342D556612205B2B461F592837131019481225212F225B2A
Difficulty & Points: 1
Description:
A simple monoalphabetic substitution cipher.
[Author: Hayz]
Ciphertext:
pviaxdv r iqxny sqj djqk eql yvajc cv mrsyng djqkkvy eql fv jcv iallraov cvny pxj wxdj qxldvnbvd asy rffqljanrjg
Difficulty & Points: 3
Description:
A monoalphabetic substitution cipher. Fairly simple, except all punctuation and spaces have been removed. Good luck. :) P.S. The solution should be submitted with spaces, but without any punctuation at all for it to be validated properly. Case does not matter.
[Author: Hayz]
Ciphertext:
xfzkxuadskgfvnwglnnktwltelvkxfzkxualtlokevfzgsudlrkduxd
kwfewkxlvklsfnwgldsdsfxkgsfeurfvelvkcydleldsuwdfikvlxsd
glokldsltblbtfgktfypsfesudkdfbtfgdsudefvwkxdvyodlftlokl
xunxfpvkudutwgfynwxyeelok
Difficulty & Points: 1
Description:
Research the term Atbash and then solve this problem.
[Author: Hayz]
Ciphertext:
plmtizxsllozgvlmh
Difficulty & Points: 6
Description:
This is a vigenere cipher. Solve it and submit the key (in lowercase).
[Author: Hayz]
Ciphertext:
njpykeyyitzzvzhiprrwerptlijfvlivxawetvhbxnztvitnelgvtwwhhrmmlac
wsrfkvnicmtkellhzirqezmpkizvdbjsacivbsmnzjnwjxbgzptkiavwpimmqde
ovwhjaqcwepulbwcmlvacjgksrvpvakklfeigngvqeimwoppfeovakmobpfspym
favavfsyesgptbzzmojiejcqdupqropenazsogumgfgwzvlgzwdrjeytcvyigeh
meziyfvwsaozvfgymghcqxvvgjwxhdvwargesyhvhkdmpxaamomcghgklxemutw
wqwlxeqmygryymmicwckiuwvhqcqdeswklvehmlklcitlajzolsukvbozbswtcx
egwrqezlgzwmlzwywajfabpgzfdivyifadbssrkisgwxmalvgrrwxmmlvswkxai
rqywshrpfmbpeqkquwymzznwepxiksiptkgnfedeilzflkjxambpezitvatwvvl
eiyimmxzvezimzrzsastfkurrwxcmwgvffjesmldbsjewtavvlfkgcwmeiltfkk
exaincyllkjegkztdzswkiwegwfvxqrpexcmmavfjxaeoepjihccbrbptylqmik
lzioarvyilotkzeijvvxkvbswvvfkxxcmcsxvyizvziexicjxmlvbrghkjkbzdv
rllgiipmgtmwxjvjeinpzxokekljjzjgycehmlznwwwjfjzvzieyipvvtpniyvl
gisxwoppxpgjlhjcwckiurrwxcmtjvkuikwvvogjccpdmildgjovrvmoqkwrurr
wwgigwwudeepvvoyvgrxtxoptktqzrmnjpykeyklxfzidlakkltpgbswokeklsa
bswicixaeilezikiekqdmdyevyikiybzyivyikxjntylvklxvdlpjepulbwvzxq
fwkxaiwmlkxyrwmefmyhvkjsgimbzyivyikadbsllgweewzxcgtjvxpljplvaqi
oxhhqcsgnvwhroppticjxlfzpldjcehucoppelcuhxgzqgwhccppljplvfgvruv
vvowhyzxaxcmxsvmfjmlzjpswvrrwajzdzmrgiwldadlevlilxcmmweukeghopp
xenjiivjxswxyvvxxczzorccmoidvegxjvjbimgwsogfjuymvtfkulpilpzldpv
yikinbhwvgbmepzlmqxjvwpsmlhzmeygtqzwflshklxqjcezshklxvdlpjepuee
popptmtuwpimmrgvivhpmopezikijeinp
Difficulty & Points: 7
Description:
Solve this vigenere cipher. You'll probably need help from Kasiski, if you get my drift. Supply the key for the solution.
[Author: Hayz]
Ciphertext:
liyzswatbkthzarckwodxjvjznslimrvnsliwlkhqcfgcfrpobahrsqvpvsvaemsqtxttweqyka
zufjkkwqwozkgemlflhzgdsnaoettwdqvyedlffz
Difficulty & Points: 6
Description:
Weak passwords are bad; Break this Blowfish ciphertext by any means possible. Submit the password to correctly answer the puzzle.
The source used for this cipher can be found here. You won't solve the problem without it. (This problem is not especially hard, it's more of a hands-on, real-world application where you have to adapt and be able to use what's available to solve the problem).
[Author: Hayz]
Ciphertext:
b0i.d/KqOWH0XQFnH0Xj8zY/ihriU0cud2c0C94qL.TBQBA1p/40G/6yYWg1aeNn4.7q6760
Difficulty & Points: 2
Description:
I received a cipher using this method of encryption, at which time I had no idea what it was or how it was encrypted. Solve it and post the plaintext as the answer.
[Author: Hayz]
Ciphertext:
Hppe!kpc/!Tpnfpjnft!pijoht!bsf!fbtjfs!pibo!pifz!mppl/
Difficulty & Points: 6
Description:
Solve this problem and provide the author's last name as the solution.
[Author: Hayz]
Ciphertext:
ziztl ietfl tjigzwz, tfeigtl, dylmfgol ei ijdjtl, wjyl logjigmfjil ei tfzygztl ogxjyg ietgtlzt xgngtfwj, izmfwj, wjieyl tewiztl, tzngmfeye njiwj mflmflmfl, ziztnlozi ojigteyl mflmflmfl, mflmflmfl tfzngtfldeygt "tlozmfl", ilywj, "mflmflmfl tfzngtfldeygt; wztldl."
Difficulty & Points: 12
Description:
This is a secret CIA Document that has been encrypted with an algorithm of my own making, WeakHaze16. It's a 16 bit symmetric block cipher that takes a 64 bit key. The document is a real classified US government document that has been declassified, and you have to break this to read it.
The encrypted file is available here. The code for WeakHaze16 is available in Delphi and C++.
The password used for the cipher may or may not have been hashed; brute force alone is not the best attack here.
To complete the problem decrypt the file and submit the 10th word of the second paragraph as the solution.
[Author: Hayz]
Difficulty & Points: 6
Description:
Solve this classic cipher and submit the last word of the puzzle as the solution. [Author: Ruptor]
Ciphertext:
asoewcotd bcaz mhc efntzr hunadeyo ltlpao ne ozaauywui oiloc bamkdhm ieoloiatenc oal lsltti bo zgce ttd aiea nrlhoiniaur etfwili lcnadn slagtueiip lnpmrpyto ftt rbfielale nuiorov rpwrzykot dnrof oayas owutsjg
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