475 lines
14 KiB
C
475 lines
14 KiB
C
/*
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* aes_gcm_wssl.c
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*
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* AES Galois Counter Mode using wolfSSL
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*
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* Sean Parkinson, wolfSSL
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*
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*/
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/*
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*
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* Copyright (c) 2013-2017, Cisco Systems, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*
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* Neither the name of the Cisco Systems, Inc. nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#ifndef WOLFSSL_USER_SETTINGS
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#include <wolfssl/options.h>
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#endif
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#include <wolfssl/wolfcrypt/settings.h>
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#include <wolfssl/wolfcrypt/aes.h>
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#include "aes_gcm.h"
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#include "alloc.h"
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#include "err.h" /* for srtp_debug */
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#include "crypto_types.h"
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#include "cipher_types.h"
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#include "cipher_test_cases.h"
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srtp_debug_module_t srtp_mod_aes_gcm = {
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0, /* debugging is off by default */
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"aes gcm wssl" /* printable module name */
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};
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/**
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* SRTP IV Formation for AES-GCM
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* https://tools.ietf.org/html/rfc7714#section-8.1
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* 0 0 0 0 0 0 0 0 0 0 1 1
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* 0 1 2 3 4 5 6 7 8 9 0 1
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* +--+--+--+--+--+--+--+--+--+--+--+--+
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* |00|00| SSRC | ROC | SEQ |---+
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* +--+--+--+--+--+--+--+--+--+--+--+--+ |
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* |
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* +--+--+--+--+--+--+--+--+--+--+--+--+ |
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* | Encryption Salt |->(+)
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* +--+--+--+--+--+--+--+--+--+--+--+--+ |
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* |
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* +--+--+--+--+--+--+--+--+--+--+--+--+ |
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* | Initialization Vector |<--+
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* +--+--+--+--+--+--+--+--+--+--+--+--+
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*
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* SRTCP IV Formation for AES-GCM
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* https://tools.ietf.org/html/rfc7714#section-9.1
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*
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*/
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/*
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* For now we only support 8 and 16 octet tags. The spec allows for
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* optional 12 byte tag, which may be supported in the future.
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*/
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#define GCM_AUTH_TAG_LEN AES_BLOCK_SIZE
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#define GCM_AUTH_TAG_LEN_8 8
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#define FUNC_ENTRY() debug_print(srtp_mod_aes_gcm, "%s entry", __func__);
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/*
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* This function allocates a new instance of this crypto engine.
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* The key_len parameter should be one of 28 or 44 for
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* AES-128-GCM or AES-256-GCM respectively. Note that the
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* key length includes the 14 byte salt value that is used when
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* initializing the KDF.
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*/
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static srtp_err_status_t srtp_aes_gcm_wolfssl_alloc(srtp_cipher_t **c,
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size_t key_len,
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size_t tlen)
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{
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FUNC_ENTRY();
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srtp_aes_gcm_ctx_t *gcm;
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debug_print(srtp_mod_aes_gcm, "allocating cipher with key length %zu",
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key_len);
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debug_print(srtp_mod_aes_gcm, "allocating cipher with tag length %zu",
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tlen);
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/*
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* Verify the key_len is valid for one of: AES-128/256
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*/
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if (key_len != SRTP_AES_GCM_128_KEY_LEN_WSALT &&
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key_len != SRTP_AES_GCM_256_KEY_LEN_WSALT) {
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return (srtp_err_status_bad_param);
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}
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if (tlen != GCM_AUTH_TAG_LEN && tlen != GCM_AUTH_TAG_LEN_8) {
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return (srtp_err_status_bad_param);
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}
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/* allocate memory a cipher of type aes_gcm */
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*c = (srtp_cipher_t *)srtp_crypto_alloc(sizeof(srtp_cipher_t));
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if (*c == NULL) {
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return (srtp_err_status_alloc_fail);
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}
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gcm = (srtp_aes_gcm_ctx_t *)srtp_crypto_alloc(sizeof(srtp_aes_gcm_ctx_t));
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if (gcm == NULL) {
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srtp_crypto_free(*c);
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*c = NULL;
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return (srtp_err_status_alloc_fail);
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}
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gcm->ctx = NULL;
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/* set pointers */
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(*c)->state = gcm;
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/* setup cipher attributes */
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switch (key_len) {
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case SRTP_AES_GCM_128_KEY_LEN_WSALT:
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(*c)->type = &srtp_aes_gcm_128;
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(*c)->algorithm = SRTP_AES_GCM_128;
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gcm->key_size = SRTP_AES_128_KEY_LEN;
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gcm->tag_len = tlen;
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break;
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case SRTP_AES_GCM_256_KEY_LEN_WSALT:
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(*c)->type = &srtp_aes_gcm_256;
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(*c)->algorithm = SRTP_AES_GCM_256;
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gcm->key_size = SRTP_AES_256_KEY_LEN;
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gcm->tag_len = tlen;
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break;
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}
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/* set key size */
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(*c)->key_len = key_len;
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return (srtp_err_status_ok);
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}
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/*
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* This function deallocates a GCM session
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*/
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static srtp_err_status_t srtp_aes_gcm_wolfssl_dealloc(srtp_cipher_t *c)
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{
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srtp_aes_gcm_ctx_t *ctx;
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FUNC_ENTRY();
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ctx = (srtp_aes_gcm_ctx_t *)c->state;
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if (ctx != NULL) {
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if (ctx->ctx != NULL) {
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wc_AesFree(ctx->ctx);
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srtp_crypto_free(ctx->ctx);
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}
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/* zeroize the key material */
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octet_string_set_to_zero(ctx, sizeof(srtp_aes_gcm_ctx_t));
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srtp_crypto_free(ctx);
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}
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/* free memory */
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srtp_crypto_free(c);
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return (srtp_err_status_ok);
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}
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static srtp_err_status_t srtp_aes_gcm_wolfssl_context_init(void *cv,
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const uint8_t *key)
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{
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FUNC_ENTRY();
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srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv;
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int err;
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c->dir = srtp_direction_any;
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#ifndef WOLFSSL_AESGCM_STREAM
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c->aad_size = 0;
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#endif
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debug_print(srtp_mod_aes_gcm, "key: %s",
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srtp_octet_string_hex_string(key, c->key_size));
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switch (c->key_size) {
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case SRTP_AES_256_KEY_LEN:
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case SRTP_AES_128_KEY_LEN:
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break;
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default:
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return (srtp_err_status_bad_param);
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break;
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}
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if (c->ctx == NULL) {
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c->ctx = (Aes *)srtp_crypto_alloc(sizeof(Aes));
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if (c->ctx == NULL) {
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return srtp_err_status_alloc_fail;
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}
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err = wc_AesInit(c->ctx, NULL, INVALID_DEVID);
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if (err < 0) {
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srtp_crypto_free(c->ctx);
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c->ctx = NULL;
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debug_print(srtp_mod_aes_gcm, "wolfSSL error code: %d", err);
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return srtp_err_status_init_fail;
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}
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}
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err = wc_AesGcmSetKey(c->ctx, (const unsigned char *)key, c->key_size);
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if (err < 0) {
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debug_print(srtp_mod_aes_gcm, "wolfSSL error code: %d", err);
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return srtp_err_status_init_fail;
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}
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return (srtp_err_status_ok);
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}
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static srtp_err_status_t srtp_aes_gcm_wolfssl_set_iv(
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void *cv,
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uint8_t *iv,
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srtp_cipher_direction_t direction)
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{
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FUNC_ENTRY();
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srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv;
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#ifdef WOLFSSL_AESGCM_STREAM
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int err;
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#endif
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if (direction != srtp_direction_encrypt &&
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direction != srtp_direction_decrypt) {
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return (srtp_err_status_bad_param);
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}
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c->dir = direction;
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debug_print(srtp_mod_aes_gcm, "setting iv: %s",
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srtp_octet_string_hex_string(iv, GCM_NONCE_MID_SZ));
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#ifndef WOLFSSL_AESGCM_STREAM
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c->iv_len = GCM_NONCE_MID_SZ;
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memcpy(c->iv, iv, c->iv_len);
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c->aad_size = 0;
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#else
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err = wc_AesGcmInit(c->ctx, NULL, 0, iv, GCM_NONCE_MID_SZ);
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if (err < 0) {
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debug_print(srtp_mod_aes_gcm, "wolfSSL error code: %d", err);
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return srtp_err_status_init_fail;
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}
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#endif
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return (srtp_err_status_ok);
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}
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/*
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* This function processes the AAD
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*
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* Parameters:
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* c Crypto context
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* aad Additional data to process for AEAD cipher suites
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* aad_len length of aad buffer
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*/
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static srtp_err_status_t srtp_aes_gcm_wolfssl_set_aad(void *cv,
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const uint8_t *aad,
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size_t aad_len)
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{
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FUNC_ENTRY();
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srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv;
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#ifdef WOLFSSL_AESGCM_STREAM
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int err;
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#endif
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debug_print(srtp_mod_aes_gcm, "setting AAD: %s",
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srtp_octet_string_hex_string(aad, aad_len));
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#ifndef WOLFSSL_AESGCM_STREAM
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if (aad_len + c->aad_size > MAX_AD_SIZE) {
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return srtp_err_status_bad_param;
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}
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memcpy(c->aad + c->aad_size, aad, aad_len);
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c->aad_size += aad_len;
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#else
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if (c->dir == srtp_direction_encrypt) {
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err = wc_AesGcmEncryptUpdate(c->ctx, NULL, NULL, 0, aad, aad_len);
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} else {
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err = wc_AesGcmDecryptUpdate(c->ctx, NULL, NULL, 0, aad, aad_len);
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}
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if (err < 0) {
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debug_print(srtp_mod_aes_gcm, "wolfSSL error code: %d", err);
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return srtp_err_status_algo_fail;
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}
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#endif
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return (srtp_err_status_ok);
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}
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/*
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* This function encrypts a buffer using AES GCM mode
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*
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* Parameters:
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* c Crypto context
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* buf data to encrypt
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* enc_len length of encrypt buffer
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*/
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static srtp_err_status_t srtp_aes_gcm_wolfssl_encrypt(void *cv,
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const uint8_t *src,
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size_t src_len,
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uint8_t *dst,
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size_t *dst_len)
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{
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FUNC_ENTRY();
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srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv;
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int err;
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if (c->dir != srtp_direction_encrypt) {
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return srtp_err_status_bad_param;
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}
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if (*dst_len < src_len + c->tag_len) {
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return srtp_err_status_buffer_small;
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}
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#ifndef WOLFSSL_AESGCM_STREAM
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// tag must always be 16 bytes when passed to wc_AesGcmEncrypt, can truncate
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// to c->tag_len after
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uint8_t tag[GCM_AUTH_TAG_LEN];
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err = wc_AesGcmEncrypt(c->ctx, dst, src, src_len, c->iv, c->iv_len, tag,
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sizeof(tag), c->aad, c->aad_size);
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c->aad_size = 0;
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if (err == 0) {
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memcpy(dst + src_len, tag, c->tag_len);
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}
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#else
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err = wc_AesGcmEncryptUpdate(c->ctx, dst, src, src_len, NULL, 0);
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if (err < 0) {
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debug_print(srtp_mod_aes_gcm, "wolfSSL error code: %d", err);
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return srtp_err_status_algo_fail;
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}
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err = wc_AesGcmEncryptFinal(c->ctx, dst + src_len, c->tag_len);
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#endif
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if (err < 0) {
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debug_print(srtp_mod_aes_gcm, "wolfSSL error code: %d", err);
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printf("wolfSSL error code: %d\n", err);
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return srtp_err_status_algo_fail;
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}
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*dst_len = src_len + c->tag_len;
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return srtp_err_status_ok;
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}
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/*
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* This function decrypts a buffer using AES GCM mode
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*
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* Parameters:
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* c Crypto context
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* buf data to encrypt
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* enc_len length of encrypt buffer
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*/
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static srtp_err_status_t srtp_aes_gcm_wolfssl_decrypt(void *cv,
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const uint8_t *src,
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size_t src_len,
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uint8_t *dst,
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size_t *dst_len)
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{
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FUNC_ENTRY();
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srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv;
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int err;
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if (c->dir != srtp_direction_decrypt) {
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return srtp_err_status_bad_param;
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}
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if (src_len < c->tag_len) {
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return srtp_err_status_bad_param;
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}
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if (*dst_len < src_len - c->tag_len) {
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return srtp_err_status_buffer_small;
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}
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#ifndef WOLFSSL_AESGCM_STREAM
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debug_print(srtp_mod_aes_gcm, "AAD: %s",
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srtp_octet_string_hex_string(c->aad, c->aad_size));
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err = wc_AesGcmDecrypt(c->ctx, dst, src, (src_len - c->tag_len), c->iv,
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c->iv_len, src + (src_len - c->tag_len), c->tag_len,
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c->aad, c->aad_size);
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c->aad_size = 0;
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#else
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err = wc_AesGcmDecryptUpdate(c->ctx, dst, src, (src_len - c->tag_len), NULL,
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0);
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if (err < 0) {
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debug_print(srtp_mod_aes_gcm, "wolfSSL error code: %d", err);
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return srtp_err_status_algo_fail;
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}
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err =
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wc_AesGcmDecryptFinal(c->ctx, src + (src_len - c->tag_len), c->tag_len);
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#endif
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if (err < 0) {
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debug_print(srtp_mod_aes_gcm, "wolfSSL error code: %d", err);
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return srtp_err_status_auth_fail;
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}
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/*
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* Reduce the buffer size by the tag length since the tag
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* is not part of the original payload
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*/
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*dst_len = src_len -= c->tag_len;
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return srtp_err_status_ok;
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}
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/*
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* Name of this crypto engine
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*/
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static const char srtp_aes_gcm_128_wolfssl_description[] =
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"AES-128 GCM using wolfssl";
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static const char srtp_aes_gcm_256_wolfssl_description[] =
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"AES-256 GCM using wolfssl";
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/*
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* This is the vector function table for this crypto engine.
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*/
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/* clang-format off */
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const srtp_cipher_type_t srtp_aes_gcm_128 = {
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srtp_aes_gcm_wolfssl_alloc,
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srtp_aes_gcm_wolfssl_dealloc,
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srtp_aes_gcm_wolfssl_context_init,
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srtp_aes_gcm_wolfssl_set_aad,
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srtp_aes_gcm_wolfssl_encrypt,
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srtp_aes_gcm_wolfssl_decrypt,
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srtp_aes_gcm_wolfssl_set_iv,
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srtp_aes_gcm_128_wolfssl_description,
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&srtp_aes_gcm_128_test_case_0,
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SRTP_AES_GCM_128
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};
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/* clang-format on */
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/*
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* This is the vector function table for this crypto engine.
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*/
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/* clang-format off */
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const srtp_cipher_type_t srtp_aes_gcm_256 = {
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srtp_aes_gcm_wolfssl_alloc,
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srtp_aes_gcm_wolfssl_dealloc,
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srtp_aes_gcm_wolfssl_context_init,
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srtp_aes_gcm_wolfssl_set_aad,
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srtp_aes_gcm_wolfssl_encrypt,
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srtp_aes_gcm_wolfssl_decrypt,
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srtp_aes_gcm_wolfssl_set_iv,
|
|
srtp_aes_gcm_256_wolfssl_description,
|
|
&srtp_aes_gcm_256_test_case_0,
|
|
SRTP_AES_GCM_256
|
|
};
|
|
/* clang-format on */
|