utls_hmac_init:: (gnutls_hmac_hd_t * DIG, gnutls_mac_algorithm_t ALGORITHM, const void * KEY, size_t KEYLEN)’
‘INT *note gnutls_hmac:: (gnutls_hmac_hd_t HANDLE, const void * PTEXT, size_t PTEXT_LEN)’
‘VOID *note gnutls_hmac_output:: (gnutls_hmac_hd_t HANDLE, void * DIGEST)’
‘VOID *note gnutls_hmac_deinit:: (gnutls_hmac_hd_t HANDLE, void * DIGEST)’
‘UNSIGNED *note gnutls_hmac_get_len:: (gnutls_mac_algorithm_t ALGORITHM)’
‘INT *note gnutls_hmac_fast:: (gnutls_mac_algorithm_t ALGORITHM, const void * KEY, size_t KEYLEN, const void * PTEXT, size_t PTEXT_LEN, void * DIGEST)’

The available functions to access hash functions are shown below.  The
supported hash functions are shown in *note Figure 9.4:
gnutls_digest_algorithm_t.

‘INT *note gnutls_hash_init:: (gnutls_hash_hd_t * DIG, gnutls_digest_algorithm_t ALGORITHM)’
‘INT *note gnutls_hash:: (gnutls_hash_hd_t HANDLE, const void * PTEXT, size_t PTEXT_LEN)’
‘VOID *note gnutls_hash_output:: (gnutls_hash_hd_t HANDLE, void * DIGEST)’
‘VOID *note gnutls_hash_deinit:: (gnutls_hash_hd_t HANDLE, void * DIGEST)’
‘UNSIGNED *note gnutls_hash_get_len:: (gnutls_digest_algorithm_t ALGORITHM)’
‘INT *note gnutls_hash_fast:: (gnutls_digest_algorithm_t ALGORITHM, const void * PTEXT, size_t PTEXT_LEN, void * DIGEST)’
‘INT *note gnutls_fingerprint:: (gnutls_digest_algorithm_t ALGO, const gnutls_datum_t * DATA, void * RESULT, size_t * RESULT_SIZE)’

‘GNUTLS_DIG_UNKNOWN’
     Unknown hash algorithm.
‘GNUTLS_DIG_NULL’
     NULL hash algorithm (empty output).
‘GNUTLS_DIG_MD5’
     MD5 algorithm.
‘GNUTLS_DIG_SHA1’
     SHA-1 algorithm.
‘GNUTLS_DIG_RMD160’
     RMD160 algorithm.
‘GNUTLS_DIG_MD2’
     MD2 algorithm.
‘GNUTLS_DIG_SHA256’
     SHA-256 algorithm.
‘GNUTLS_DIG_SHA384’
     SHA-384 algorithm.
‘GNUTLS_DIG_SHA512’
     SHA-512 algorithm.
‘GNUTLS_DIG_SHA224’
     SHA-224 algorithm.
‘GNUTLS_DIG_SHA3_224’
     SHA3-224 algorithm.
‘GNUTLS_DIG_SHA3_256’
     SHA3-256 algorithm.
‘GNUTLS_DIG_SHA3_384’
     SHA3-384 algorithm.
‘GNUTLS_DIG_SHA3_512’
     SHA3-512 algorithm.
‘GNUTLS_DIG_MD5_SHA1’
     Combined MD5+SHA1 algorithm.
‘GNUTLS_DIG_GOSTR_94’
     GOST R 34.11-94 algorithm.
‘GNUTLS_DIG_STREEBOG_256’
     GOST R 34.11-2001 (Streebog) algorithm, 256 bit.
‘GNUTLS_DIG_STREEBOG_512’
     GOST R 34.11-2001 (Streebog) algorithm, 512 bit.
‘GNUTLS_DIG_SHAKE_128’
     The SHAKE128 extendable output function.
‘GNUTLS_DIG_SHAKE_256’
     The SHAKE256 extendable output function.

Figure 9.4: The supported hash algorithms.