xref: /dports/security/gnutls/gnutls-3.6.16/lib/crypto-api.c

/*
 * Copyright (C) 2000-2016 Free Software Foundation, Inc.
 * Copyright (C) 2016 Red Hat, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>
 *
 */

#include "gnutls_int.h"
#include "errors.h"
#include <cipher_int.h>
#include <datum.h>
#include <gnutls/crypto.h>
#include <algorithms.h>
#include <random.h>
#include <crypto.h>
#include <fips.h>
#include "crypto-api.h"
#include "iov.h"

typedef struct api_cipher_hd_st {
	cipher_hd_st ctx_enc;
	cipher_hd_st ctx_dec;
} api_cipher_hd_st;

/**
 * gnutls_cipher_init:
 * @handle: is a #gnutls_cipher_hd_t type
 * @cipher: the encryption algorithm to use
 * @key: the key to be used for encryption/decryption
 * @iv: the IV to use (if not applicable set NULL)
 *
 * This function will initialize the @handle context to be usable
 * for encryption/decryption of data. This will effectively use the
 * current crypto backend in use by gnutls or the cryptographic
 * accelerator in use.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.10.0
 **/
int
gnutls_cipher_init(gnutls_cipher_hd_t * handle,
		   gnutls_cipher_algorithm_t cipher,
		   const gnutls_datum_t * key, const gnutls_datum_t * iv)
{
	api_cipher_hd_st *h;
	int ret;
	const cipher_entry_st* e;

	if (is_cipher_algo_forbidden(cipher))
		return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);

	e = cipher_to_entry(cipher);
	if (e == NULL || (e->flags & GNUTLS_CIPHER_FLAG_ONLY_AEAD))
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	h = gnutls_calloc(1, sizeof(api_cipher_hd_st));
	if (h == NULL) {
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}

	ret =
	    _gnutls_cipher_init(&h->ctx_enc, e, key,
				iv, 1);
	if (ret < 0) {
		gnutls_free(h);
		return ret;
	}

	if (_gnutls_cipher_type(e) == CIPHER_BLOCK) {
		ret =
		    _gnutls_cipher_init(&h->ctx_dec, e, key, iv, 0);
		if (ret < 0) {
			gnutls_free(h);
			return ret;
		}
	}

	*handle = h;

	return ret;
}

/**
 * gnutls_cipher_tag:
 * @handle: is a #gnutls_cipher_hd_t type
 * @tag: will hold the tag
 * @tag_size: the length of the tag to return
 *
 * This function operates on authenticated encryption with
 * associated data (AEAD) ciphers and will return the
 * output tag.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.0
 **/
int
gnutls_cipher_tag(gnutls_cipher_hd_t handle, void *tag, size_t tag_size)
{
	api_cipher_hd_st *h = handle;

	if (_gnutls_cipher_is_aead(&h->ctx_enc) == 0)
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	_gnutls_cipher_tag(&h->ctx_enc, tag, tag_size);

	return 0;
}

/**
 * gnutls_cipher_add_auth:
 * @handle: is a #gnutls_cipher_hd_t type
 * @ptext: the data to be authenticated
 * @ptext_size: the length of the data
 *
 * This function operates on authenticated encryption with
 * associated data (AEAD) ciphers and authenticate the
 * input data. This function can only be called once
 * and before any encryption operations.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.0
 **/
int
gnutls_cipher_add_auth(gnutls_cipher_hd_t handle, const void *ptext,
		       size_t ptext_size)
{
	api_cipher_hd_st *h = handle;

	if (_gnutls_cipher_is_aead(&h->ctx_enc) == 0)
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	return _gnutls_cipher_auth(&h->ctx_enc, ptext, ptext_size);
}

/**
 * gnutls_cipher_set_iv:
 * @handle: is a #gnutls_cipher_hd_t type
 * @iv: the IV to set
 * @ivlen: the length of the IV
 *
 * This function will set the IV to be used for the next
 * encryption block.
 *
 * Since: 3.0
 **/
void
gnutls_cipher_set_iv(gnutls_cipher_hd_t handle, void *iv, size_t ivlen)
{
	api_cipher_hd_st *h = handle;

	if (_gnutls_cipher_setiv(&h->ctx_enc, iv, ivlen) < 0) {
		_gnutls_switch_lib_state(LIB_STATE_ERROR);
	}

	if (_gnutls_cipher_type(h->ctx_enc.e) == CIPHER_BLOCK)
		if (_gnutls_cipher_setiv(&h->ctx_dec, iv, ivlen) < 0) {
			_gnutls_switch_lib_state(LIB_STATE_ERROR);
		}
}

/*-
 * _gnutls_cipher_get_iv:
 * @handle: is a #gnutls_cipher_hd_t type
 * @iv: the IV to set
 * @ivlen: the length of the IV
 *
 * This function will retrieve the internally calculated IV value. It is
 * intended to be used  for modes like CFB. @iv must have @ivlen length
 * at least.
 *
 * This is solely for validation purposes of our crypto
 * implementation.  For other purposes, the IV can be typically
 * calculated from the initial IV value and the subsequent ciphertext
 * values.  As such, this function only works with the internally
 * registered ciphers.
 *
 * Returns: The length of IV or a negative error code on error.
 *
 * Since: 3.6.8
 -*/
int
_gnutls_cipher_get_iv(gnutls_cipher_hd_t handle, void *iv, size_t ivlen)
{
	api_cipher_hd_st *h = handle;

	return _gnutls_cipher_getiv(&h->ctx_enc, iv, ivlen);
}

/**
 * gnutls_cipher_encrypt:
 * @handle: is a #gnutls_cipher_hd_t type
 * @ptext: the data to encrypt
 * @ptext_len: the length of data to encrypt
 *
 * This function will encrypt the given data using the algorithm
 * specified by the context.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.10.0
 **/
int
gnutls_cipher_encrypt(gnutls_cipher_hd_t handle, void *ptext,
		      size_t ptext_len)
{
	api_cipher_hd_st *h = handle;

	return _gnutls_cipher_encrypt(&h->ctx_enc, ptext, ptext_len);
}

/**
 * gnutls_cipher_decrypt:
 * @handle: is a #gnutls_cipher_hd_t type
 * @ctext: the data to decrypt
 * @ctext_len: the length of data to decrypt
 *
 * This function will decrypt the given data using the algorithm
 * specified by the context.
 *
 * Note that in AEAD ciphers, this will not check the tag. You will
 * need to compare the tag sent with the value returned from gnutls_cipher_tag().
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.10.0
 **/
int
gnutls_cipher_decrypt(gnutls_cipher_hd_t handle, void *ctext,
		      size_t ctext_len)
{
	api_cipher_hd_st *h = handle;

	if (_gnutls_cipher_type(h->ctx_enc.e) != CIPHER_BLOCK)
		return _gnutls_cipher_decrypt(&h->ctx_enc, ctext,
					      ctext_len);
	else
		return _gnutls_cipher_decrypt(&h->ctx_dec, ctext,
					      ctext_len);
}

/**
 * gnutls_cipher_encrypt2:
 * @handle: is a #gnutls_cipher_hd_t type
 * @ptext: the data to encrypt
 * @ptext_len: the length of data to encrypt
 * @ctext: the encrypted data
 * @ctext_len: the available length for encrypted data
 *
 * This function will encrypt the given data using the algorithm
 * specified by the context. For block ciphers the @ptext_len must be
 * a multiple of the block size. For the supported ciphers the encrypted
 * data length will equal the plaintext size.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.12.0
 **/
int
gnutls_cipher_encrypt2(gnutls_cipher_hd_t handle, const void *ptext,
		       size_t ptext_len, void *ctext,
		       size_t ctext_len)
{
	api_cipher_hd_st *h = handle;

	return _gnutls_cipher_encrypt2(&h->ctx_enc, ptext, ptext_len,
				       ctext, ctext_len);
}

/**
 * gnutls_cipher_decrypt2:
 * @handle: is a #gnutls_cipher_hd_t type
 * @ctext: the data to decrypt
 * @ctext_len: the length of data to decrypt
 * @ptext: the decrypted data
 * @ptext_len: the available length for decrypted data
 *
 * This function will decrypt the given data using the algorithm
 * specified by the context. For block ciphers the @ctext_len must be
 * a multiple of the block size. For the supported ciphers the plaintext
 * data length will equal the ciphertext size.
 *
 * Note that in AEAD ciphers, this will not check the tag. You will
 * need to compare the tag sent with the value returned from gnutls_cipher_tag().
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.12.0
 **/
int
gnutls_cipher_decrypt2(gnutls_cipher_hd_t handle, const void *ctext,
		       size_t ctext_len, void *ptext, size_t ptext_len)
{
	api_cipher_hd_st *h = handle;

	if (_gnutls_cipher_type(h->ctx_enc.e) != CIPHER_BLOCK)
		return _gnutls_cipher_decrypt2(&h->ctx_enc, ctext,
					       ctext_len, ptext,
					       ptext_len);
	else
		return _gnutls_cipher_decrypt2(&h->ctx_dec, ctext,
					       ctext_len, ptext,
					       ptext_len);
}

/**
 * gnutls_cipher_deinit:
 * @handle: is a #gnutls_cipher_hd_t type
 *
 * This function will deinitialize all resources occupied by the given
 * encryption context.
 *
 * Since: 2.10.0
 **/
void gnutls_cipher_deinit(gnutls_cipher_hd_t handle)
{
	api_cipher_hd_st *h = handle;

	_gnutls_cipher_deinit(&h->ctx_enc);
	if (_gnutls_cipher_type(h->ctx_enc.e) == CIPHER_BLOCK)
		_gnutls_cipher_deinit(&h->ctx_dec);
	gnutls_free(handle);
}


/* HMAC */


/**
 * gnutls_hmac_init:
 * @dig: is a #gnutls_hmac_hd_t type
 * @algorithm: the HMAC algorithm to use
 * @key: the key to be used for encryption
 * @keylen: the length of the key
 *
 * This function will initialize an context that can be used to
 * produce a Message Authentication Code (MAC) of data.  This will
 * effectively use the current crypto backend in use by gnutls or the
 * cryptographic accelerator in use.
 *
 * Note that despite the name of this function, it can be used
 * for other MAC algorithms than HMAC.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.10.0
 **/
int
gnutls_hmac_init(gnutls_hmac_hd_t * dig,
		 gnutls_mac_algorithm_t algorithm,
		 const void *key, size_t keylen)
{
	/* MD5 is only allowed internally for TLS */
	if (is_mac_algo_forbidden(algorithm))
		return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);

	*dig = gnutls_malloc(sizeof(mac_hd_st));
	if (*dig == NULL) {
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}

	return _gnutls_mac_init(((mac_hd_st *) * dig),
				mac_to_entry(algorithm), key, keylen);
}

/**
 * gnutls_hmac_set_nonce:
 * @handle: is a #gnutls_hmac_hd_t type
 * @nonce: the data to set as nonce
 * @nonce_len: the length of data
 *
 * This function will set the nonce in the MAC algorithm.
 *
 * Since: 3.2.0
 **/
void
gnutls_hmac_set_nonce(gnutls_hmac_hd_t handle, const void *nonce,
		      size_t nonce_len)
{
	_gnutls_mac_set_nonce((mac_hd_st *) handle, nonce, nonce_len);
}

/**
 * gnutls_hmac:
 * @handle: is a #gnutls_hmac_hd_t type
 * @ptext: the data to hash
 * @ptext_len: the length of data to hash
 *
 * This function will hash the given data using the algorithm
 * specified by the context.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.10.0
 **/
int gnutls_hmac(gnutls_hmac_hd_t handle, const void *ptext, size_t ptext_len)
{
	return _gnutls_mac((mac_hd_st *) handle, ptext, ptext_len);
}

/**
 * gnutls_hmac_output:
 * @handle: is a #gnutls_hmac_hd_t type
 * @digest: is the output value of the MAC
 *
 * This function will output the current MAC value
 * and reset the state of the MAC.
 *
 * Since: 2.10.0
 **/
void gnutls_hmac_output(gnutls_hmac_hd_t handle, void *digest)
{
	_gnutls_mac_output((mac_hd_st *) handle, digest);
}

/**
 * gnutls_hmac_deinit:
 * @handle: is a #gnutls_hmac_hd_t type
 * @digest: is the output value of the MAC
 *
 * This function will deinitialize all resources occupied by
 * the given hmac context.
 *
 * Since: 2.10.0
 **/
void gnutls_hmac_deinit(gnutls_hmac_hd_t handle, void *digest)
{
	_gnutls_mac_deinit((mac_hd_st *) handle, digest);
	gnutls_free(handle);
}

/**
 * gnutls_hmac_get_len:
 * @algorithm: the hmac algorithm to use
 *
 * This function will return the length of the output data
 * of the given hmac algorithm.
 *
 * Returns: The length or zero on error.
 *
 * Since: 2.10.0
 **/
unsigned gnutls_hmac_get_len(gnutls_mac_algorithm_t algorithm)
{
	return _gnutls_mac_get_algo_len(mac_to_entry(algorithm));
}

/**
 * gnutls_hmac_get_key_size:
 * @algorithm: the mac algorithm to use
 *
 * This function will return the size of the key to be used with this
 * algorithm. On the algorithms which may accept arbitrary key sizes,
 * the returned size is the MAC key size used in the TLS protocol.
 *
 * Returns: The key size or zero on error.
 *
 * Since: 3.6.12
 **/
unsigned gnutls_hmac_get_key_size(gnutls_mac_algorithm_t algorithm)
{
	return _gnutls_mac_get_key_size(mac_to_entry(algorithm));
}

/**
 * gnutls_hmac_fast:
 * @algorithm: the hash algorithm to use
 * @key: the key to use
 * @keylen: the length of the key
 * @ptext: the data to hash
 * @ptext_len: the length of data to hash
 * @digest: is the output value of the hash
 *
 * This convenience function will hash the given data and return output
 * on a single call. Note, this call will not work for MAC algorithms
 * that require nonce (like UMAC or GMAC).
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.10.0
 **/
int
gnutls_hmac_fast(gnutls_mac_algorithm_t algorithm,
		 const void *key, size_t keylen,
		 const void *ptext, size_t ptext_len, void *digest)
{
	if (is_mac_algo_forbidden(algorithm))
		return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);

	return _gnutls_mac_fast(algorithm, key, keylen, ptext, ptext_len,
				digest);
}

/**
 * gnutls_hmac_copy:
 * @handle: is a #gnutls_hmac_hd_t type
 *
 * This function will create a copy of MAC context, containing all its current
 * state. Copying contexts for MACs registered using
 * gnutls_crypto_register_mac() is not supported and will always result in an
 * error.
 *
 * Returns: new MAC context or NULL in case of an error.
 *
 * Since: 3.6.9
 */
gnutls_hmac_hd_t gnutls_hmac_copy(gnutls_hmac_hd_t handle)
{
	gnutls_hmac_hd_t dig;

	dig = gnutls_malloc(sizeof(mac_hd_st));
	if (dig == NULL) {
		gnutls_assert();
		return NULL;
	}

	if (_gnutls_mac_copy((const mac_hd_st *) handle, (mac_hd_st *)dig) != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		gnutls_free(dig);
		return NULL;
	}

	return dig;
}

/* HASH */

/**
 * gnutls_hash_init:
 * @dig: is a #gnutls_hash_hd_t type
 * @algorithm: the hash algorithm to use
 *
 * This function will initialize an context that can be used to
 * produce a Message Digest of data.  This will effectively use the
 * current crypto backend in use by gnutls or the cryptographic
 * accelerator in use.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.10.0
 **/
int
gnutls_hash_init(gnutls_hash_hd_t * dig,
		 gnutls_digest_algorithm_t algorithm)
{
	if (is_mac_algo_forbidden(DIG_TO_MAC(algorithm)))
		return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);

	*dig = gnutls_malloc(sizeof(digest_hd_st));
	if (*dig == NULL) {
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}

	return _gnutls_hash_init(((digest_hd_st *) * dig),
				 hash_to_entry(algorithm));
}

/**
 * gnutls_hash:
 * @handle: is a #gnutls_hash_hd_t type
 * @ptext: the data to hash
 * @ptext_len: the length of data to hash
 *
 * This function will hash the given data using the algorithm
 * specified by the context.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.10.0
 **/
int gnutls_hash(gnutls_hash_hd_t handle, const void *ptext, size_t ptext_len)
{
	return _gnutls_hash((digest_hd_st *) handle, ptext, ptext_len);
}

/**
 * gnutls_hash_output:
 * @handle: is a #gnutls_hash_hd_t type
 * @digest: is the output value of the hash
 *
 * This function will output the current hash value
 * and reset the state of the hash.
 *
 * Since: 2.10.0
 **/
void gnutls_hash_output(gnutls_hash_hd_t handle, void *digest)
{
	_gnutls_hash_output((digest_hd_st *) handle, digest);
}

/**
 * gnutls_hash_deinit:
 * @handle: is a #gnutls_hash_hd_t type
 * @digest: is the output value of the hash
 *
 * This function will deinitialize all resources occupied by
 * the given hash context.
 *
 * Since: 2.10.0
 **/
void gnutls_hash_deinit(gnutls_hash_hd_t handle, void *digest)
{
	_gnutls_hash_deinit((digest_hd_st *) handle, digest);
	gnutls_free(handle);
}

/**
 * gnutls_hash_get_len:
 * @algorithm: the hash algorithm to use
 *
 * This function will return the length of the output data
 * of the given hash algorithm.
 *
 * Returns: The length or zero on error.
 *
 * Since: 2.10.0
 **/
unsigned gnutls_hash_get_len(gnutls_digest_algorithm_t algorithm)
{
	return _gnutls_hash_get_algo_len(hash_to_entry(algorithm));
}

/**
 * gnutls_hash_fast:
 * @algorithm: the hash algorithm to use
 * @ptext: the data to hash
 * @ptext_len: the length of data to hash
 * @digest: is the output value of the hash
 *
 * This convenience function will hash the given data and return output
 * on a single call.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 2.10.0
 **/
int
gnutls_hash_fast(gnutls_digest_algorithm_t algorithm,
		 const void *ptext, size_t ptext_len, void *digest)
{
	if (is_mac_algo_forbidden(DIG_TO_MAC(algorithm)))
		return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);

	return _gnutls_hash_fast(algorithm, ptext, ptext_len, digest);
}

/**
 * gnutls_hash_copy:
 * @handle: is a #gnutls_hash_hd_t type
 *
 * This function will create a copy of Message Digest context, containing all
 * its current state. Copying contexts for Message Digests registered using
 * gnutls_crypto_register_digest() is not supported and will always result in
 * an error.
 *
 * Returns: new Message Digest context or NULL in case of an error.
 *
 * Since: 3.6.9
 */
gnutls_hash_hd_t gnutls_hash_copy(gnutls_hash_hd_t handle)
{
	gnutls_hash_hd_t dig;

	dig = gnutls_malloc(sizeof(digest_hd_st));
	if (dig == NULL) {
		gnutls_assert();
		return NULL;
	}

	if (_gnutls_hash_copy((const digest_hd_st *) handle, (digest_hd_st *)dig) != GNUTLS_E_SUCCESS) {
		gnutls_assert();
		gnutls_free(dig);
		return NULL;
	}

	return dig;
}

/**
 * gnutls_key_generate:
 * @key: is a pointer to a #gnutls_datum_t which will contain a newly
 * created key
 * @key_size: the number of bytes of the key
 *
 * Generates a random key of @key_size bytes.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, or an
 * error code.
 *
 * Since: 3.0
 **/
int gnutls_key_generate(gnutls_datum_t * key, unsigned int key_size)
{
	int ret;

	FAIL_IF_LIB_ERROR;

#ifdef ENABLE_FIPS140
	/* The FIPS140 approved RNGs are not allowed to be used
	 * to extract key sizes longer than their original seed.
	 */
	if (_gnutls_fips_mode_enabled() != 0 &&
	    key_size > FIPS140_RND_KEY_SIZE)
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
#endif

	key->size = key_size;
	key->data = gnutls_malloc(key->size);
	if (!key->data) {
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}

	ret = gnutls_rnd(GNUTLS_RND_RANDOM, key->data, key->size);
	if (ret < 0) {
		gnutls_assert();
		_gnutls_free_datum(key);
		return ret;
	}

	return 0;
}

/* AEAD API */

/**
 * gnutls_aead_cipher_init:
 * @handle: is a #gnutls_aead_cipher_hd_t type.
 * @cipher: the authenticated-encryption algorithm to use
 * @key: The key to be used for encryption
 *
 * This function will initialize an context that can be used for
 * encryption/decryption of data. This will effectively use the
 * current crypto backend in use by gnutls or the cryptographic
 * accelerator in use.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.4.0
 **/
int gnutls_aead_cipher_init(gnutls_aead_cipher_hd_t *handle,
			    gnutls_cipher_algorithm_t cipher,
			    const gnutls_datum_t *key)
{
	api_aead_cipher_hd_st *h;
	const cipher_entry_st *e;
	int ret;

	if (is_cipher_algo_forbidden(cipher))
		return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);

	e = cipher_to_entry(cipher);
	if (e == NULL || e->type != CIPHER_AEAD)
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	h = gnutls_calloc(1, sizeof(api_aead_cipher_hd_st));
	if (h == NULL) {
		gnutls_assert();
		return GNUTLS_E_MEMORY_ERROR;
	}

	ret = _gnutls_aead_cipher_init(h, cipher, key);
	if (ret < 0) {
		gnutls_free(h);
		return ret;
	}

	*handle = h;

	return ret;
}

/**
 * gnutls_aead_cipher_decrypt:
 * @handle: is a #gnutls_aead_cipher_hd_t type.
 * @nonce: the nonce to set
 * @nonce_len: The length of the nonce
 * @auth: additional data to be authenticated
 * @auth_len: The length of the data
 * @tag_size: The size of the tag to use (use zero for the default)
 * @ctext: the data to decrypt (including the authentication tag)
 * @ctext_len: the length of data to decrypt (includes tag size)
 * @ptext: the decrypted data
 * @ptext_len: the length of decrypted data (initially must hold the maximum available size)
 *
 * This function will decrypt the given data using the algorithm
 * specified by the context. This function must be provided the complete
 * data to be decrypted, including the authentication tag. On several
 * AEAD ciphers, the authentication tag is appended to the ciphertext,
 * though this is not a general rule. This function will fail if
 * the tag verification fails.
 *
 * Returns: Zero or a negative error code on verification failure or other error.
 *
 * Since: 3.4.0
 **/
int
gnutls_aead_cipher_decrypt(gnutls_aead_cipher_hd_t handle,
			   const void *nonce, size_t nonce_len,
			   const void *auth, size_t auth_len,
			   size_t tag_size,
			   const void *ctext, size_t ctext_len,
			   void *ptext, size_t *ptext_len)
{
	int ret;
	api_aead_cipher_hd_st *h = handle;

	if (tag_size == 0)
		tag_size = _gnutls_cipher_get_tag_size(h->ctx_enc.e);
	else if (tag_size > (unsigned)_gnutls_cipher_get_tag_size(h->ctx_enc.e))
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	if (unlikely(ctext_len < tag_size))
		return gnutls_assert_val(GNUTLS_E_DECRYPTION_FAILED);

	ret = _gnutls_aead_cipher_decrypt(&h->ctx_enc,
					  nonce, nonce_len,
					  auth, auth_len,
					  tag_size,
					  ctext, ctext_len,
					  ptext, *ptext_len);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);

	/* That assumes that AEAD ciphers are stream */
	*ptext_len = ctext_len - tag_size;

	return 0;
}


/**
 * gnutls_aead_cipher_encrypt:
 * @handle: is a #gnutls_aead_cipher_hd_t type.
 * @nonce: the nonce to set
 * @nonce_len: The length of the nonce
 * @auth: additional data to be authenticated
 * @auth_len: The length of the data
 * @tag_size: The size of the tag to use (use zero for the default)
 * @ptext: the data to encrypt
 * @ptext_len: The length of data to encrypt
 * @ctext: the encrypted data including authentication tag
 * @ctext_len: the length of encrypted data (initially must hold the maximum available size, including space for tag)
 *
 * This function will encrypt the given data using the algorithm
 * specified by the context. The output data will contain the
 * authentication tag.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.4.0
 **/
int
gnutls_aead_cipher_encrypt(gnutls_aead_cipher_hd_t handle,
			   const void *nonce, size_t nonce_len,
			   const void *auth, size_t auth_len,
			   size_t tag_size,
			   const void *ptext, size_t ptext_len,
			   void *ctext, size_t *ctext_len)
{
	api_aead_cipher_hd_st *h = handle;
	int ret;

	if (tag_size == 0)
		tag_size = _gnutls_cipher_get_tag_size(h->ctx_enc.e);
	else if (tag_size > (unsigned)_gnutls_cipher_get_tag_size(h->ctx_enc.e))
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	if (unlikely(*ctext_len < ptext_len + tag_size))
		return gnutls_assert_val(GNUTLS_E_SHORT_MEMORY_BUFFER);

	ret = _gnutls_aead_cipher_encrypt(&h->ctx_enc,
					  nonce, nonce_len,
					  auth, auth_len,
					  tag_size,
					  ptext, ptext_len,
					  ctext, *ctext_len);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);

	/* That assumes that AEAD ciphers are stream */
	*ctext_len = ptext_len + tag_size;

	return 0;
}

struct iov_store_st {
	void *data;
	size_t size;
};

static void iov_store_free(struct iov_store_st *s)
{
	gnutls_free(s->data);
}

static int iov_store_grow(struct iov_store_st *s, size_t length)
{
	void *data;

	s->size += length;
	data = gnutls_realloc(s->data, s->size);
	if (data == NULL)
		return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

	s->data = data;
	return 0;
}

static int
copy_from_iov(struct iov_store_st *dst, const giovec_t *iov, int iovcnt)
{
	memset(dst, 0, sizeof(*dst));
	if (iovcnt == 0) {
		return 0;
	} else {
		int i;
		uint8_t *p;

		dst->size = 0;
		for (i=0;i<iovcnt;i++)
			dst->size += iov[i].iov_len;
		dst->data = gnutls_malloc(dst->size);
		if (dst->data == NULL)
			return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

		p = dst->data;
		for (i=0;i<iovcnt;i++) {
			if (iov[i].iov_len > 0)
				memcpy(p, iov[i].iov_base, iov[i].iov_len);
			p += iov[i].iov_len;
		}

		return 0;
	}
}

static int
copy_to_iov(struct iov_store_st *src, size_t size,
	    const giovec_t *iov, int iovcnt)
{
	size_t offset = 0;
	int i;

	if (unlikely(src->size < size))
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	for (i = 0; i < iovcnt && size > 0; i++) {
		size_t to_copy = MIN(size, iov[i].iov_len);
		memcpy(iov[i].iov_base, (uint8_t *) src->data + offset, to_copy);
		offset += to_copy;
		size -= to_copy;
	}
	if (size > 0)
		return gnutls_assert_val(GNUTLS_E_SHORT_MEMORY_BUFFER);
	return 0;
}


/**
 * gnutls_aead_cipher_encryptv:
 * @handle: is a #gnutls_aead_cipher_hd_t type.
 * @nonce: the nonce to set
 * @nonce_len: The length of the nonce
 * @auth_iov: additional data to be authenticated
 * @auth_iovcnt: The number of buffers in @auth_iov
 * @tag_size: The size of the tag to use (use zero for the default)
 * @iov: the data to be encrypted
 * @iovcnt: The number of buffers in @iov
 * @ctext: the encrypted data including authentication tag
 * @ctext_len: the length of encrypted data (initially must hold the maximum available size, including space for tag)
 *
 * This function will encrypt the provided data buffers using the algorithm
 * specified by the context. The output data will contain the
 * authentication tag.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.6.3
 **/
int
gnutls_aead_cipher_encryptv(gnutls_aead_cipher_hd_t handle,
			    const void *nonce, size_t nonce_len,
			    const giovec_t *auth_iov, int auth_iovcnt,
			    size_t tag_size,
			    const giovec_t *iov, int iovcnt,
			    void *ctext, size_t *ctext_len)
{
	api_aead_cipher_hd_st *h = handle;
	ssize_t ret;
	uint8_t *dst;
	size_t dst_size, total = 0;
	uint8_t *p;
	size_t len;
	size_t blocksize = handle->ctx_enc.e->blocksize;
	struct iov_iter_st iter;

	/* Limitation: this function provides an optimization under the internally registered
	 * AEAD ciphers. When an AEAD cipher is used registered with gnutls_crypto_register_aead_cipher(),
	 * then this becomes a convenience function as it missed the lower-level primitives
	 * necessary for piecemeal encryption. */

	if (tag_size == 0)
		tag_size = _gnutls_cipher_get_tag_size(h->ctx_enc.e);
	else if (tag_size > (unsigned)_gnutls_cipher_get_tag_size(h->ctx_enc.e))
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	if ((handle->ctx_enc.e->flags & GNUTLS_CIPHER_FLAG_ONLY_AEAD) || handle->ctx_enc.encrypt == NULL) {
		/* ciphertext cannot be produced in a piecemeal approach */
		struct iov_store_st auth;
		struct iov_store_st ptext;

		ret = copy_from_iov(&auth, auth_iov, auth_iovcnt);
		if (ret < 0)
			return gnutls_assert_val(ret);

		ret = copy_from_iov(&ptext, iov, iovcnt);
		if (ret < 0) {
			iov_store_free(&auth);
			return gnutls_assert_val(ret);
		}

		ret = gnutls_aead_cipher_encrypt(handle, nonce, nonce_len,
						 auth.data, auth.size,
						 tag_size,
						 ptext.data, ptext.size,
						 ctext, ctext_len);
		iov_store_free(&auth);
		iov_store_free(&ptext);

		return ret;
	}

	ret = _gnutls_cipher_setiv(&handle->ctx_enc, nonce, nonce_len);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);

	ret = _gnutls_iov_iter_init(&iter, auth_iov, auth_iovcnt, blocksize);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);
	while (1) {
		ret = _gnutls_iov_iter_next(&iter, &p);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
		if (ret == 0)
			break;
		ret = _gnutls_cipher_auth(&handle->ctx_enc, p, ret);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
	}

	dst = ctext;
	dst_size = *ctext_len;

	ret = _gnutls_iov_iter_init(&iter, iov, iovcnt, blocksize);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);
	while (1) {
		ret = _gnutls_iov_iter_next(&iter, &p);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
		if (ret == 0)
			break;
		len = ret;
		ret = _gnutls_cipher_encrypt2(&handle->ctx_enc,
					      p, len,
					      dst, dst_size);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
		DECR_LEN(dst_size, len);
		dst += len;
		total += len;
	}

	if (dst_size < tag_size)
		return gnutls_assert_val(GNUTLS_E_SHORT_MEMORY_BUFFER);

	_gnutls_cipher_tag(&handle->ctx_enc, dst, tag_size);

	total += tag_size;
	*ctext_len = total;

	return 0;
}

/**
 * gnutls_aead_cipher_encryptv2:
 * @handle: is a #gnutls_aead_cipher_hd_t type.
 * @nonce: the nonce to set
 * @nonce_len: The length of the nonce
 * @auth_iov: additional data to be authenticated
 * @auth_iovcnt: The number of buffers in @auth_iov
 * @iov: the data to be encrypted
 * @iovcnt: The number of buffers in @iov
 * @tag: The authentication tag
 * @tag_size: The size of the tag to use (use zero for the default)
 *
 * This is similar to gnutls_aead_cipher_encrypt(), but it performs
 * in-place encryption on the provided data buffers.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.6.10
 **/
int
gnutls_aead_cipher_encryptv2(gnutls_aead_cipher_hd_t handle,
			     const void *nonce, size_t nonce_len,
			     const giovec_t *auth_iov, int auth_iovcnt,
			     const giovec_t *iov, int iovcnt,
			     void *tag, size_t *tag_size)
{
	api_aead_cipher_hd_st *h = handle;
	ssize_t ret;
	uint8_t *p;
	size_t len;
	ssize_t blocksize = handle->ctx_enc.e->blocksize;
	struct iov_iter_st iter;
	size_t _tag_size;

	if (tag_size == NULL || *tag_size == 0)
		_tag_size = _gnutls_cipher_get_tag_size(h->ctx_enc.e);
	else
		_tag_size = *tag_size;

	if (_tag_size > (unsigned)_gnutls_cipher_get_tag_size(h->ctx_enc.e))
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	/* Limitation: this function provides an optimization under the internally registered
	 * AEAD ciphers. When an AEAD cipher is used registered with gnutls_crypto_register_aead_cipher(),
	 * then this becomes a convenience function as it missed the lower-level primitives
	 * necessary for piecemeal encryption. */
	if ((handle->ctx_enc.e->flags & GNUTLS_CIPHER_FLAG_ONLY_AEAD) || handle->ctx_enc.encrypt == NULL) {
		/* ciphertext cannot be produced in a piecemeal approach */
		struct iov_store_st auth;
		struct iov_store_st ptext;
		size_t ptext_size;

		ret = copy_from_iov(&auth, auth_iov, auth_iovcnt);
		if (ret < 0)
			return gnutls_assert_val(ret);

		ret = copy_from_iov(&ptext, iov, iovcnt);
		if (ret < 0) {
			gnutls_assert();
			goto fallback_fail;
		}

		ptext_size = ptext.size;

		/* append space for tag */
		ret = iov_store_grow(&ptext, _tag_size);
		if (ret < 0) {
			gnutls_assert();
			goto fallback_fail;
		}

		ret = gnutls_aead_cipher_encrypt(handle, nonce, nonce_len,
						 auth.data, auth.size,
						 _tag_size,
						 ptext.data, ptext_size,
						 ptext.data, &ptext.size);
		if (ret < 0) {
			gnutls_assert();
			goto fallback_fail;
		}

		ret = copy_to_iov(&ptext, ptext_size, iov, iovcnt);
		if (ret < 0) {
			gnutls_assert();
			goto fallback_fail;
		}

		if (tag != NULL)
			memcpy(tag,
			       (uint8_t *) ptext.data + ptext_size,
			       _tag_size);
		if (tag_size != NULL)
			*tag_size = _tag_size;

	fallback_fail:
		iov_store_free(&auth);
		iov_store_free(&ptext);

		return ret;
	}

	ret = _gnutls_cipher_setiv(&handle->ctx_enc, nonce, nonce_len);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);

	ret = _gnutls_iov_iter_init(&iter, auth_iov, auth_iovcnt, blocksize);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);
	while (1) {
		ret = _gnutls_iov_iter_next(&iter, &p);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
		if (ret == 0)
			break;
		ret = _gnutls_cipher_auth(&handle->ctx_enc, p, ret);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
	}

	ret = _gnutls_iov_iter_init(&iter, iov, iovcnt, blocksize);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);
	while (1) {
		ret = _gnutls_iov_iter_next(&iter, &p);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
		if (ret == 0)
			break;

		len = ret;
		ret = _gnutls_cipher_encrypt2(&handle->ctx_enc, p, len, p, len);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);

		ret = _gnutls_iov_iter_sync(&iter, p, len);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
	}

	if (tag != NULL)
		_gnutls_cipher_tag(&handle->ctx_enc, tag, _tag_size);
	if (tag_size != NULL)
		*tag_size = _tag_size;

	return 0;
}

/**
 * gnutls_aead_cipher_decryptv2:
 * @handle: is a #gnutls_aead_cipher_hd_t type.
 * @nonce: the nonce to set
 * @nonce_len: The length of the nonce
 * @auth_iov: additional data to be authenticated
 * @auth_iovcnt: The number of buffers in @auth_iov
 * @iov: the data to decrypt
 * @iovcnt: The number of buffers in @iov
 * @tag: The authentication tag
 * @tag_size: The size of the tag to use (use zero for the default)
 *
 * This is similar to gnutls_aead_cipher_decrypt(), but it performs
 * in-place encryption on the provided data buffers.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.6.10
 **/
int
gnutls_aead_cipher_decryptv2(gnutls_aead_cipher_hd_t handle,
			     const void *nonce, size_t nonce_len,
			     const giovec_t *auth_iov, int auth_iovcnt,
			     const giovec_t *iov, int iovcnt,
			     void *tag, size_t tag_size)
{
	api_aead_cipher_hd_st *h = handle;
	ssize_t ret;
	uint8_t *p;
	size_t len;
	ssize_t blocksize = handle->ctx_enc.e->blocksize;
	struct iov_iter_st iter;
	uint8_t _tag[MAX_HASH_SIZE];

	if (tag_size == 0)
		tag_size = _gnutls_cipher_get_tag_size(h->ctx_enc.e);
	else if (tag_size > (unsigned)_gnutls_cipher_get_tag_size(h->ctx_enc.e))
		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	/* Limitation: this function provides an optimization under the internally registered
	 * AEAD ciphers. When an AEAD cipher is used registered with gnutls_crypto_register_aead_cipher(),
	 * then this becomes a convenience function as it missed the lower-level primitives
	 * necessary for piecemeal encryption. */
	if ((handle->ctx_enc.e->flags & GNUTLS_CIPHER_FLAG_ONLY_AEAD) || handle->ctx_enc.encrypt == NULL) {
		/* ciphertext cannot be produced in a piecemeal approach */
		struct iov_store_st auth;
		struct iov_store_st ctext;
		size_t ctext_size;

		ret = copy_from_iov(&auth, auth_iov, auth_iovcnt);
		if (ret < 0)
			return gnutls_assert_val(ret);

		ret = copy_from_iov(&ctext, iov, iovcnt);
		if (ret < 0) {
			gnutls_assert();
			goto fallback_fail;
		}

		ctext_size = ctext.size;

		/* append tag */
		ret = iov_store_grow(&ctext, tag_size);
		if (ret < 0) {
			gnutls_assert();
			goto fallback_fail;
		}
		memcpy((uint8_t *) ctext.data + ctext_size, tag, tag_size);

		ret = gnutls_aead_cipher_decrypt(handle, nonce, nonce_len,
						 auth.data, auth.size,
						 tag_size,
						 ctext.data, ctext.size,
						 ctext.data, &ctext_size);
		if (ret < 0) {
			gnutls_assert();
			goto fallback_fail;
		}

		ret = copy_to_iov(&ctext, ctext_size, iov, iovcnt);
		if (ret < 0) {
			gnutls_assert();
			goto fallback_fail;
		}

	fallback_fail:
		iov_store_free(&auth);
		iov_store_free(&ctext);

		return ret;
	}

	ret = _gnutls_cipher_setiv(&handle->ctx_enc, nonce, nonce_len);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);

	ret = _gnutls_iov_iter_init(&iter, auth_iov, auth_iovcnt, blocksize);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);
	while (1) {
		ret = _gnutls_iov_iter_next(&iter, &p);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
		if (ret == 0)
			break;
		ret = _gnutls_cipher_auth(&handle->ctx_enc, p, ret);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
	}

	ret = _gnutls_iov_iter_init(&iter, iov, iovcnt, blocksize);
	if (unlikely(ret < 0))
		return gnutls_assert_val(ret);
	while (1) {
		ret = _gnutls_iov_iter_next(&iter, &p);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
		if (ret == 0)
			break;

		len = ret;
		ret = _gnutls_cipher_decrypt2(&handle->ctx_enc, p, len, p, len);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);

		ret = _gnutls_iov_iter_sync(&iter, p, len);
		if (unlikely(ret < 0))
			return gnutls_assert_val(ret);
	}

	if (tag != NULL) {
		_gnutls_cipher_tag(&handle->ctx_enc, _tag, tag_size);
		if (gnutls_memcmp(_tag, tag, tag_size) != 0)
			return gnutls_assert_val(GNUTLS_E_DECRYPTION_FAILED);
	}

	return 0;
}

/**
 * gnutls_aead_cipher_deinit:
 * @handle: is a #gnutls_aead_cipher_hd_t type.
 *
 * This function will deinitialize all resources occupied by the given
 * authenticated-encryption context.
 *
 * Since: 3.4.0
 **/
void gnutls_aead_cipher_deinit(gnutls_aead_cipher_hd_t handle)
{
	_gnutls_aead_cipher_deinit(handle);
	gnutls_free(handle);
}

extern gnutls_crypto_kdf_st _gnutls_kdf_ops;

/**
 * gnutls_hkdf_extract:
 * @mac: the mac algorithm used internally
 * @key: the initial keying material
 * @salt: the optional salt
 * @output: the output value of the extract operation
 *
 * This function will derive a fixed-size key using the HKDF-Extract
 * function as defined in RFC 5869.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.6.13
 */
int
gnutls_hkdf_extract(gnutls_mac_algorithm_t mac,
		    const gnutls_datum_t *key,
		    const gnutls_datum_t *salt,
		    void *output)
{
	/* MD5 is only allowed internally for TLS */
	if (is_mac_algo_forbidden(mac))
		return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);

	return _gnutls_kdf_ops.hkdf_extract(mac, key->data, key->size,
					    salt ? salt->data : NULL,
					    salt ? salt->size : 0,
					    output);
}

/**
 * gnutls_hkdf_expand:
 * @mac: the mac algorithm used internally
 * @key: the pseudorandom key created with HKDF-Extract
 * @info: the optional informational data
 * @output: the output value of the expand operation
 * @length: the desired length of the output key
 *
 * This function will derive a variable length keying material from
 * the pseudorandom key using the HKDF-Expand function as defined in
 * RFC 5869.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.6.13
 */
int
gnutls_hkdf_expand(gnutls_mac_algorithm_t mac,
		   const gnutls_datum_t *key,
		   const gnutls_datum_t *info,
		   void *output, size_t length)
{
	/* MD5 is only allowed internally for TLS */
	if (is_mac_algo_forbidden(mac))
		return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);

	return _gnutls_kdf_ops.hkdf_expand(mac, key->data, key->size,
					   info->data, info->size,
					   output, length);
}

/**
 * gnutls_pbkdf2:
 * @mac: the mac algorithm used internally
 * @key: the initial keying material
 * @salt: the salt
 * @iter_count: the iteration count
 * @output: the output value
 * @length: the desired length of the output key
 *
 * This function will derive a variable length keying material from
 * a password according to PKCS #5 PBKDF2.
 *
 * Returns: Zero or a negative error code on error.
 *
 * Since: 3.6.13
 */
int
gnutls_pbkdf2(gnutls_mac_algorithm_t mac,
	      const gnutls_datum_t *key,
	      const gnutls_datum_t *salt,
	      unsigned iter_count,
	      void *output, size_t length)
{
	/* MD5 is only allowed internally for TLS */
	if (is_mac_algo_forbidden(mac))
		return gnutls_assert_val(GNUTLS_E_UNWANTED_ALGORITHM);

	return _gnutls_kdf_ops.pbkdf2(mac, key->data, key->size,
				      salt->data, salt->size, iter_count,
				      output, length);
}