Source crypto/sha512.h

// SafeC Standard Library — SHA-512 / SHA-384 Hash (FIPS 180-4)
// Freestanding-safe. No dynamic allocation.
// Sha512Ctx conforms to hash.h's Hasher and BlockHash (generic hashing, Hmac).
#pragma once
#include <std/crypto/buf.h>

#define SHA512_DIGEST_SIZE  64   // bytes
#define SHA384_DIGEST_SIZE  48   // bytes
#define SHA512_BLOCK_SIZE   128  // bytes

namespace std {

struct Sha512Ctx {
    unsigned long long h[8];               // current hash state
    unsigned char       buf[SHA512_BLOCK_SIZE]; // partial block buffer
    // Total bytes processed. SHA-512's length field is 128 bits, but a
    // single 64-bit counter is tracked here (matching every other hash
    // module in this library) since no realistic input reaches 2^64 bytes
    // — the length field's high 8 bytes are simply written as zero.
    unsigned long long  total_bytes;
    int                 is384;             // 1 = SHA-384 variant

    // A fresh SHA-512 context.
    static struct Sha512Ctx new();

    // A fresh SHA-384 context (same struct, is384 = 1).
    static struct Sha512Ctx new_384();

    // Feed `len` bytes of data into the hash.
    void update([]const unsigned char data);
    // internal: the (reference, length) core of update()
    void update_n_(const &unsigned char data, unsigned long len);

    // Finalise and write the digest.
    // For SHA-512: digest must be at least 64 bytes.
    // For SHA-384: digest must be at least 48 bytes.
    void finish([]unsigned char digest);
    // internal: the (reference, length) core of finish()
    void finish_n_(&unsigned char digest);

    // 64 (SHA-512) or 48 (SHA-384) / SHA512_BLOCK_SIZE (hash.h's BlockHash).
    unsigned long digest_size() const;
    unsigned long block_size() const;
};

// Convenience: hash `len` bytes and write the 64-byte digest.
void sha512([]const unsigned char data, []unsigned char digest);
// internal: the (reference, length) core of sha512()
void sha512_n_(const &unsigned char data, unsigned long len,
            &unsigned char digest);

// Convenience: hash `len` bytes and write the 48-byte digest.
void sha384([]const unsigned char data, []unsigned char digest);
// internal: the (reference, length) core of sha384()
void sha384_n_(const &unsigned char data, unsigned long len,
            &unsigned char digest);

} // namespace std