What is the Process to Decrypt Ciphertexts Encrypted with the Same One Time Pad?

[everQuest]

Hi everyone

I've been given a challenge and i was wondering if you guys could shed some light on it...

i have been given two ciphertexts that have been encrypted with the same one time pad... the ciphertexts start the same (message header), but I am not given any more information about it...

the ciphertexts are split up into the same number of blocks so i think padding may have been used...

im assuming xor, they haven't given us any information (im also assuming one time pad used twice, because of the message headers)...

heres the cipher texts so you see what i mean

3:17am :
UWCHR IFLFK AFFTG WVOOM SZYUJ
QVGBR LZFSC CWAXZ KCIUE KDZEA
RIAAY HHJTN DLCWV CIIJE WARON
JEDZO IKFNM AFJJL FVSZE MEFOM

4:29am :
UWCHR IFLFK AFFTG WVOHI LDOQX
NYQUE PHRSC BDIBB FHMTI VKVOA
RHMTQ EZACG INLDH ALTHI ISGHV
AGSPI WPJML BSICH BKZNX TAFGE

so they start the same, each cipher text has exactly 100 characters in it, I've xor'd the ciphertexts but I am not quite sure what to do next.

Also there is a hint from one guy who has solved this cipher:

just look at the time at which the ciphertext was sent: 3:17( = 3x60+17 = 197) and 4:29 ( = 4x60 + 29 = 269), both of these are primes.

any help would be great!

 

[Dragonfall]

Two primes are used in the RSA algorithm, so that's my guess.

 

[tacman]

Hi there,

It seems like you have been given a challenging task! It is definitely possible to decrypt these ciphertexts, but it may require some trial and error. Here are a few things you can try to help you decrypt the messages:

1. Use the XOR method: As you mentioned, it is likely that the ciphertexts were encrypted using the XOR method. This means that you can XOR the two ciphertexts together to get the original message. However, since they were encrypted using the same one time pad, you will need to find the key used to encrypt them. This can be done by guessing the key and then XORing it with one of the ciphertexts. If the result looks like a readable message, then you have found the correct key. If not, try another key until you find the correct one.

2. Look for patterns: Since the ciphertexts start the same, it is possible that the original message also starts with the same words or phrases. Try to look for patterns in the ciphertexts that may help you guess the key or the original message.

3. Use the hint: The hint given by the person who solved this cipher may be the key to decrypting the messages. The fact that the times are prime numbers may be a clue to the key used to encrypt the messages. Try using the prime numbers 197 and 269 as keys and see if you can decrypt the messages.

4. Use frequency analysis: If all else fails, you can try using frequency analysis to decrypt the messages. This involves looking at the frequency of letters and words in the ciphertexts and comparing them to the frequency of letters and words in the English language. This can give you a hint as to what the original message may be.

I hope these tips help you in decrypting the messages. Remember to keep trying different methods and don't give up! Good luck!