March 28th, 2012, 12:47 AM
What cipher is this?
I'm a student attending CS and following System Administration and Security Classes. You should note that it's my first time ever experience with cryptic algorithms.
As a CS student I've encountered different techniques before of encrypting/decrypting but nothing like in this Class.
We've been asked to try and decrypt the following (possibly two words) to access our first assignments in a remote area of the university site:
Possible hints (and do no take them for granted):
The first should be a phrase containing the word username in it followed by the user name in-cause.
The second should be like before, containing the word password followed by a pass word.
We've taken the class which talks about some of the many cipher algorithms out there. I even believe that those two hints up there look like a substitution algorithm, but I cannot figure out if the 2nd one is the alphabet and the '1' at the end is the shift (or if it is indeed the password). But if that is the alphabet why has it repeating chars?
If I can trust the hints, the ones before the above paragraph, I can notice that none of the 1st chars correspond to the words username and password; or am I looking at them wrongfuly?
I'm not asking you to tell me the explicit values of those two hashes (where's the fun in that?). I'm trying to learn a bit about Cryptography and I require help which doesn't contain spoilers, but only friendly advices from you guys of what areas of Cryptography should I dwelve more to find out how can I finally decrypt the above two hashes myself.
Thank you in advance,
I managed to find it out eventually. It's a One Time Pad Algorithm. A really tricky one indeed.
This can be deleted by a mod.
Last edited by iSpitFire; March 29th, 2012 at 06:13 AM.
September 13th, 2012, 12:10 PM
Wow, if it was a OTP encryption then it must have taken you a while to figure out. I'm assuming you XORd the ciphertext characters with the key bits to reform the words 'username' and 'password' in each line to find that part of the key but how did you decrypt the rest of the ciphertext after the known plaintext part? It would've been possible if you had the plaintext of the first end of one ciphertext and the end of the other but it looks like 'username' and 'password' were at the beginning of both lines so the second half of each ciphertext was still perfectly secret.
Originally Posted by iSpitFire