Team

Sava Constantin-Alin, 151

Balauta Amargheoalei Albert Ionut, 152

Commands

For encryption:

python3 crypt.py password decryptedFile output

For decryption:

python3 decrypt.py ecryptedFile password output

Opponent

Team name: Spaghetti Code

Project link: https://github.com/Alexu33/proiect-1-ASC

Password: AsJY74sL93fgsd

Code Explanation

We start from the idea that the character ' ' (space) is the most used character in a Romanian text. We don't know the length of the password so we try every possibility between 10 and 15. For a k length we separate the bytes from the encrypted file into k substrings:

0, k, 2k .......................
1, k + 1, 2k + 1................
................................
k-1, k + (k-1), 2k + (k - 1)....

For each substring: We use a dictionary to find the frequency of every byte from the encrypted file. The byte with the greatest frequency corresponds to the character ' ' (space) from the original text. If we xor that byte with the ASCII code of ' ' (32) we'll find a character from the password.