Hash Functions

Cryptographic hash functions for data integrity, digital signatures, and content addressing.

Available Hash Functions

BLAKE3

Recommended - Fastest modern hash function

• 256-bit security
• Parallel hashing support
• Extendable output
• Keyed hashing (MAC mode)
• Key derivation (KDF mode)

BLAKE2b / BLAKE2s

High-speed hash functions (RFC 7693)

• BLAKE2b: optimised for 64-bit (up to 512-bit output)
• BLAKE2s: optimised for 32-bit (up to 256-bit output)
• Built-in keyed mode (MAC without HMAC)
• Faster than MD5/SHA-1/SHA-2

SHA-256

Standard hash function, widely supported

• 256-bit security
• FIPS 180-4 compliant
• Hardware acceleration (SHA-NI)

SHA-512

Large output hash function

• 512-bit output
• 256-bit security
• Faster than SHA-256 on 64-bit systems

SHA-3

NIST standard based on Keccak

• Multiple output sizes (224, 256, 384, 512)
• Different construction than SHA-2
• FIPS 202 compliant

Legacy Hash Functions

SHA-1 ⚠️ Deprecated

Cryptographically broken since 2017

• 160-bit output
• Collision attacks demonstrated (SHAttered)
• Only for legacy compatibility

MD5 ⚠️ Broken

Completely broken since 2004

• 128-bit output
• Collisions in seconds on modern hardware
• In Weak:: namespace
• Never use for security

Common Interface

All hash functions share a common interface:

class HashFunction {
public:
    // Get algorithm name
    std::string AlgorithmName() const;

    // Get digest size
    unsigned int DigestSize() const;

    // Update hash with data
    void Update(const byte* input, size_t length);

    // Finalize and get result
    void TruncatedFinal(byte* digest, size_t digestSize);

    // Reset to initial state
    void Restart();
};

Quick Reference

See Also

• Hash Functions Guide - Conceptual overview with examples
• BLAKE3 Guide - Detailed BLAKE3 guide
• Algorithm Reference - All supported algorithms