Glossary

Cipher Categories Explained

Classical Substitution

Replacing units of plaintext with ciphertext (e.g., A becomes D). Vulnerable to frequency analysis.

Classical Transposition

Rearranging the order of the letters without changing the letters themselves (an anagram).

Polygraphic Ciphers

Substituting blocks of multiple letters simultaneously rather than one at a time, increasing complexity.

Block Ciphers

Modern algorithms that encrypt data in fixed-size chunks (blocks) using complex mathematical transformations.

Stream Ciphers

Algorithms that encrypt data bit-by-bit continuously, acting like a pseudorandom noise generator mixed with the text.

Public-Key Cryptography

Using paired keys (one public, one private) so anyone can encrypt, but only the owner can decrypt.

Authenticated Encryption

Simultaneously encrypting data for privacy AND generating a tag to mathematically prove the data wasn't tampered with.

Cryptographic Hashes

One-way algorithms that turn data into a fixed-length fingerprint. Impossible to decrypt; used for verifying passwords and file integrity.