3.3c — Cryptographic Protection (13)

Plaintext

Data in its original, readable form before encryption.

Ciphertext

The unreadable result of encrypting plaintext.

Confusion (cryptography)

The property that encrypted output looks dramatically different from the original input.

Hashing

One-way function converting data into a fixed-length string. Cannot be reversed to recover the original data.

Message digest / fingerprint

Alternate names for a hash output.

Hashing vs encryption

Encryption is reversible with a key; hashing is one-way by design. Never encrypt stored passwords, always hash them.

Hash use case: passwords

Store the hash of a password, never the plaintext or an encrypted version.

Hash use case: integrity verification

Compare a downloaded file's computed hash against a published hash to confirm nothing changed in transit.

Digital signature

Hashing combined with public key cryptography; verifies both sender authenticity and message integrity.

Collision (hashing)

Two different inputs producing the same hash output. A flaw that retires a hashing algorithm from use.

SHA-256

A modern hashing algorithm producing a 256-bit (64 hex character) output.

Avalanche effect

A tiny input change (one character) produces a dramatically different hash output.

Salting

Adding random data to a password before hashing so identical passwords don't produce identical hashes, defeating precomputed rainbow-table attacks.