CL password manager

A simple command line application for storing passwords with encryption written entirely in python.

How to try

Run the main.py script; no external packages are needed. I provided a password storage for testing purposes: test_storage.pass (all entries in this storage are encoded with a my5pass password). To start, type the help command.

How the encryption is executed

The main encryption algorithm is a modified Vigenere cifer (which is a polyalphabetic form of a well-known Caesar cifer).

The crypt_tools.py file contains three cifers. The allowed characters as well as the main encryption logic is set in the VigenereCifer class. VigenereIterShiftCifer cifer applies the Vigenere cifer iteratively, each time with a shifted key string.

The following block of code explains the idea behind the iterative-shift Vigenere cifer:

message = 'hello'; key = 'a1b2c3d'
result1 = VigenereIterShiftCifer(iterations=3).encrypt(message, key)
tmp = VigenereCipher().encrypt(message, 'a1b2c3d')
tmp = VigenereCipher().encrypt(tmp, 'da1b2c3')
result2 = VigenereCipher().encrypt(tmp, '3da1b2c')
print(result1 == result2) # True

The VigenereKeySplitCifer takes it one step further. It is equivalent to the VigenereIterShiftCifer if length of the key is less than 4. Otherwise, it splits the key into two keys $k_1,;k_2$ in such a way that $\gcd(\text{len}(k_1), \text{len}(k_2)) = 1$, then uses these keys in sequence applying the VigenereIterShiftCifer to the input string. The split is increasing the effective length of the key (if the initial length is $L$, then new effective length would be approximately equal to $L^2/4$).

Note that the required minimal version of python is 3.10 (due to the new typehints and match-case syntax).