pqcrypto/crypto_sign/rainbowIa-classic/clean/utils_hash.c

/// @file utils_hash.c
/// @brief the adapter for SHA2 families.
///
///

#include "hash_len_config.h"
#include "sha2.h"
#include "utils_hash.h"

#ifndef _HASH_LEN
#define _HASH_LEN (32)
#endif

static inline
int _hash( unsigned char *digest, const unsigned char *m, unsigned long long mlen ) {
    #if 32 == _HASH_LEN
    sha256(digest, m, mlen);
    #elif 48 == _HASH_LEN
    sha384(digest, m, mlen);
    #elif 64 == _HASH_LEN
    sha512(digest, m, mlen);
    #else
#error "unsupported _HASH_LEN"
    #endif
    return 0;
}

static inline
int expand_hash( unsigned char *digest, unsigned n_digest, const unsigned char *hash ) {
    if ( _HASH_LEN >= n_digest ) {
        for (unsigned i = 0; i < n_digest; i++) {
            digest[i] = hash[i];
        }
        return 0;
    }
    for (unsigned i = 0; i < _HASH_LEN; i++) {
        digest[i] = hash[i];
    }
    n_digest -= _HASH_LEN;


    while ( _HASH_LEN <= n_digest ) {
        _hash( digest + _HASH_LEN, digest, _HASH_LEN );

        n_digest -= _HASH_LEN;
        digest += _HASH_LEN;
    }
    unsigned char temp[_HASH_LEN];
    if ( n_digest ) {
        _hash( temp, digest, _HASH_LEN );
        for (unsigned i = 0; i < n_digest; i++) {
            digest[_HASH_LEN + i] = temp[i];
        }
    }
    return 0;
}

int PQCLEAN_RAINBOWIACLASSIC_CLEAN_hash_msg( unsigned char *digest, unsigned len_digest, const unsigned char *m, unsigned long long mlen ) {
    unsigned char buf[_HASH_LEN];
    _hash( buf, m, mlen );

    return expand_hash( digest, len_digest, buf );
}