siv: add gnutls support
Add support for the AES-SIV-CMAC cipher in gnutls using the AEAD interface. It should be available in gnutls-3.6.14. This will enable NTS support on systems that have a pre-3.6 version of Nettle, without falling back to the internal SIV implementation.
This commit is contained in:
Miroslav Lichvar
parent
cf10ce1b68
commit
e8968ea429
2 changed files with 264 additions and 13 deletions
40
configure
vendored
40
configure
vendored
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@ -966,31 +966,45 @@ EXTRA_OBJECTS="$EXTRA_OBJECTS $HASH_OBJ"
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EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS $HASH_OBJ"
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LIBS="$LIBS $HASH_LINK"
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if [ $feat_ntp = "1" ] && [ $feat_nts = "1" ] && [ $try_gnutls = "1" ] && \
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echo "$HASH_LINK" | grep 'nettle' > /dev/null; then
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if [ $feat_ntp = "1" ] && [ $feat_nts = "1" ] && [ $try_gnutls = "1" ]; then
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test_cflags="`pkg_config --cflags gnutls`"
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test_link="`pkg_config --libs gnutls`"
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if test_code 'gnutls' 'gnutls/gnutls.h' \
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"$test_cflags" "$test_link" '
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return gnutls_init(NULL, 0) +
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gnutls_priority_init2(NULL, "", NULL, GNUTLS_PRIORITY_INIT_DEF_APPEND) +
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gnutls_prf_rfc5705(NULL, 0, "", 0, "", 16, NULL);' &&
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test_code 'AES128 in nettle' 'nettle/aes.h' '' "$LIBS" \
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'aes128_set_encrypt_key(NULL, NULL);'
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gnutls_prf_rfc5705(NULL, 0, "", 0, "", 16, NULL);'
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then
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EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ke_client.o nts_ke_server.o nts_ke_session.o"
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EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ntp_auth.o nts_ntp_client.o nts_ntp_server.o"
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EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
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LIBS="$LIBS $test_link"
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MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
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add_def FEAT_NTS
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add_def HAVE_SIV
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if test_code 'SIV in nettle' \
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'nettle/siv-cmac.h' "" "$LIBS" \
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'siv_cmac_aes128_set_key(NULL, NULL);'
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then
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EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
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add_def HAVE_SIV
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add_def HAVE_NETTLE_SIV_CMAC
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else
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if test_code 'SIV in gnutls' 'gnutls/gnutls.h' \
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"$test_cflags" "$test_link" '
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return gnutls_aead_cipher_init(NULL, GNUTLS_CIPHER_AES_128_SIV, NULL);'
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then
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EXTRA_OBJECTS="$EXTRA_OBJECTS siv_gnutls.o"
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add_def HAVE_SIV
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else
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if test_code 'AES128 in nettle' 'nettle/aes.h' '' "$LIBS" \
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'aes128_set_encrypt_key(NULL, NULL);'
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then
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EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
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add_def HAVE_SIV
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fi
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fi
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fi
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if grep '#define HAVE_SIV' config.h > /dev/null; then
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EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ke_client.o nts_ke_server.o nts_ke_session.o"
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EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ntp_auth.o nts_ntp_client.o nts_ntp_server.o"
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LIBS="$LIBS $test_link"
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MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
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add_def FEAT_NTS
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fi
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fi
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fi
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237
siv_gnutls.c
Normal file
237
siv_gnutls.c
Normal file
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@ -0,0 +1,237 @@
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/*
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chronyd/chronyc - Programs for keeping computer clocks accurate.
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**********************************************************************
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* Copyright (C) Miroslav Lichvar 2020
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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**********************************************************************
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=======================================================================
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SIV ciphers using the GnuTLS library
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*/
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#include "config.h"
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#include "sysincl.h"
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#include <gnutls/crypto.h>
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#include "logging.h"
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#include "memory.h"
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#include "siv.h"
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struct SIV_Instance_Record {
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gnutls_cipher_algorithm_t algorithm;
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gnutls_aead_cipher_hd_t cipher;
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};
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/* ================================================== */
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static int instance_counter = 0;
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static int gnutls_initialised = 0;
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/* ================================================== */
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static void
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init_gnutls(void)
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{
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int r;
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if (gnutls_initialised)
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return;
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r = gnutls_global_init();
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if (r < 0)
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LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
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DEBUG_LOG("Initialised");
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gnutls_initialised = 1;
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}
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/* ================================================== */
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static void
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deinit_gnutls(void)
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{
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assert(gnutls_initialised);
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gnutls_global_deinit();
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gnutls_initialised = 0;
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DEBUG_LOG("Deinitialised");
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}
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/* ================================================== */
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static gnutls_cipher_algorithm_t
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get_cipher_algorithm(SIV_Algorithm algorithm)
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{
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switch (algorithm) {
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case AEAD_AES_SIV_CMAC_256:
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return GNUTLS_CIPHER_AES_128_SIV;
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default:
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return 0;
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}
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}
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/* ================================================== */
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SIV_Instance
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SIV_CreateInstance(SIV_Algorithm algorithm)
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{
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gnutls_cipher_algorithm_t calgo;
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SIV_Instance instance;
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calgo = get_cipher_algorithm(algorithm);
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if (calgo == 0)
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return NULL;
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if (instance_counter == 0)
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init_gnutls();
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/* Check if the cipher is actually supported */
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if (gnutls_cipher_get_tag_size(calgo) == 0)
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return NULL;
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instance = MallocNew(struct SIV_Instance_Record);
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instance->algorithm = calgo;
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instance->cipher = NULL;
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instance_counter++;
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return instance;
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}
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/* ================================================== */
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void
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SIV_DestroyInstance(SIV_Instance instance)
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{
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if (instance->cipher)
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gnutls_aead_cipher_deinit(instance->cipher);
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Free(instance);
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instance_counter--;
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if (instance_counter == 0)
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deinit_gnutls();
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}
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/* ================================================== */
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int
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SIV_GetKeyLength(SIV_Algorithm algorithm)
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{
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gnutls_cipher_algorithm_t calgo = get_cipher_algorithm(algorithm);
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if (calgo == 0)
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return 0;
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return gnutls_cipher_get_key_size(calgo);
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}
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/* ================================================== */
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int
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SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length)
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{
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gnutls_aead_cipher_hd_t cipher;
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gnutls_datum_t datum;
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int r;
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if (length <= 0 || length != gnutls_cipher_get_key_size(instance->algorithm))
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return 0;
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datum.data = (unsigned char *)key;
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datum.size = length;
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/* Initialise a new cipher with the provided key (gnutls does not seem to
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have a function to change the key directly) */
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r = gnutls_aead_cipher_init(&cipher, instance->algorithm, &datum);
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if (r < 0) {
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DEBUG_LOG("Could not initialise %s : %s", "cipher", gnutls_strerror(r));
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return 0;
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}
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/* Replace the previous cipher */
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if (instance->cipher)
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gnutls_aead_cipher_deinit(instance->cipher);
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instance->cipher = cipher;
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return 1;
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}
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/* ================================================== */
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int
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SIV_GetTagLength(SIV_Instance instance)
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{
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return gnutls_cipher_get_tag_size(instance->algorithm);
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}
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/* ================================================== */
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int
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SIV_Encrypt(SIV_Instance instance,
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const unsigned char *nonce, int nonce_length,
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const void *assoc, int assoc_length,
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const void *plaintext, int plaintext_length,
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unsigned char *ciphertext, int ciphertext_length)
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{
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size_t clen = ciphertext_length;
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if (nonce_length < 1 || assoc_length < 0 ||
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plaintext_length < 0 || ciphertext_length < 0)
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return 0;
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assert(assoc && plaintext);
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if (gnutls_aead_cipher_encrypt(instance->cipher,
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nonce, nonce_length, assoc, assoc_length, 0,
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plaintext, plaintext_length, ciphertext, &clen) < 0)
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return 0;
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if (clen != ciphertext_length)
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return 0;
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return 1;
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}
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/* ================================================== */
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int
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SIV_Decrypt(SIV_Instance instance,
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const unsigned char *nonce, int nonce_length,
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const void *assoc, int assoc_length,
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const unsigned char *ciphertext, int ciphertext_length,
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void *plaintext, int plaintext_length)
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{
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size_t plen = plaintext_length;
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if (nonce_length < 1 || assoc_length < 0 ||
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plaintext_length < 0 || ciphertext_length < 0)
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return 0;
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assert(assoc && plaintext);
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if (gnutls_aead_cipher_decrypt(instance->cipher,
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nonce, nonce_length, assoc, assoc_length, 0,
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ciphertext, ciphertext_length, plaintext, &plen) < 0)
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return 0;
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if (plen != plaintext_length)
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return 0;
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return 1;
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}
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