classical-cipher-analysis

Classical cipher identification uses charset heuristics, frequency analysis, Index of Coincidence, and Kasiski examination to determine the cipher family. You then apply targeted cryptanalysis workflows like known-plaintext attacks or key-length inference to recover plaintext and keys.

Breaking a Vigenere cipher with an unknown key length involves using Kasiski examination and the Index of Coincidence to estimate key length, followed by applying frequency analysis to each identified subset to recover the full key and plaintext.

Frequency analysis for substitution ciphers works by comparing the character distribution of the ciphertext against standard language frequencies. This allows you to map encrypted characters back to their original plaintext equivalents without needing the key.

Yes, automated cryptanalysis can detect unknown encodings first by checking for base64, hex, binary, or morse-like string patterns. This ensures the correct decoding is applied before identifying the underlying cipher family.

Cracking XOR ciphers with crib-dragging involves sliding a known plaintext fragment across the ciphertext to infer the repeating key. This technique satisfies the cipher-specific requirement of known-plaintext attacks to recover the full encryption key.