classical-cipher-analysis

Classical cipher identification uses frequency analysis, Kasiski examination, and known-plaintext cryptanalysis to detect the cipher type, then applies decryption methods like substitution, Vigenere, transposition, or XOR to recover the original plaintext.

Supported classical cipher types include monoalphabetic substitution, Caesar/ROT, Vigenere, Enigma, affine, Hill, transposition, Bacon, Polybius, Playfair, and XOR ciphers, plus general encoded text decryption for CTF competitions.

Yes, classical cipher analysis requires a Python environment with numpy and sympy libraries installed to execute the mathematical operations, frequency analysis, and cryptanalysis needed for cipher identification and decryption.

Kasiski examination breaks Vigenere ciphers by finding repeated character sequences in the ciphertext to estimate the key length, enabling frequency analysis to recover individual substitution components and decrypt the encoded text.

Yes, monoalphabetic substitution ciphers can be decrypted without the key by applying frequency analysis to match ciphertext character distributions against known language patterns, inferring the substitution mapping to recover plaintext.

XOR cipher cryptanalysis is best handled using known-plaintext attacks or statistical analysis to recover the repeating key, especially when the key length is shorter than the ciphertext message in cybersecurity applications.