| /* |
| * aes_gcm_ossl.c |
| * |
| * AES Galois Counter Mode |
| * |
| * John A. Foley |
| * Cisco Systems, Inc. |
| * |
| */ |
| |
| /* |
| * |
| * Copyright (c) 2013-2017, Cisco Systems, Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials provided |
| * with the distribution. |
| * |
| * Neither the name of the Cisco Systems, Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
| * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
| * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| * OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| #include <config.h> |
| #endif |
| |
| #include <openssl/evp.h> |
| #include "aes_gcm.h" |
| #include "alloc.h" |
| #include "err.h" /* for srtp_debug */ |
| #include "crypto_types.h" |
| #include "cipher_types.h" |
| #include "cipher_test_cases.h" |
| |
| srtp_debug_module_t srtp_mod_aes_gcm = { |
| 0, /* debugging is off by default */ |
| "aes gcm" /* printable module name */ |
| }; |
| |
| /* |
| * For now we only support 8 and 16 octet tags. The spec allows for |
| * optional 12 byte tag, which may be supported in the future. |
| */ |
| #define GCM_AUTH_TAG_LEN 16 |
| #define GCM_AUTH_TAG_LEN_8 8 |
| |
| /* |
| * This function allocates a new instance of this crypto engine. |
| * The key_len parameter should be one of 28 or 44 for |
| * AES-128-GCM or AES-256-GCM respectively. Note that the |
| * key length includes the 14 byte salt value that is used when |
| * initializing the KDF. |
| */ |
| static srtp_err_status_t srtp_aes_gcm_openssl_alloc(srtp_cipher_t **c, |
| int key_len, |
| int tlen) |
| { |
| srtp_aes_gcm_ctx_t *gcm; |
| |
| debug_print(srtp_mod_aes_gcm, "allocating cipher with key length %d", |
| key_len); |
| debug_print(srtp_mod_aes_gcm, "allocating cipher with tag length %d", tlen); |
| |
| /* |
| * Verify the key_len is valid for one of: AES-128/256 |
| */ |
| if (key_len != SRTP_AES_GCM_128_KEY_LEN_WSALT && |
| key_len != SRTP_AES_GCM_256_KEY_LEN_WSALT) { |
| return (srtp_err_status_bad_param); |
| } |
| |
| if (tlen != GCM_AUTH_TAG_LEN && tlen != GCM_AUTH_TAG_LEN_8) { |
| return (srtp_err_status_bad_param); |
| } |
| |
| /* allocate memory a cipher of type aes_gcm */ |
| *c = (srtp_cipher_t *)srtp_crypto_alloc(sizeof(srtp_cipher_t)); |
| if (*c == NULL) { |
| return (srtp_err_status_alloc_fail); |
| } |
| |
| gcm = (srtp_aes_gcm_ctx_t *)srtp_crypto_alloc(sizeof(srtp_aes_gcm_ctx_t)); |
| if (gcm == NULL) { |
| srtp_crypto_free(*c); |
| *c = NULL; |
| return (srtp_err_status_alloc_fail); |
| } |
| |
| gcm->ctx = EVP_CIPHER_CTX_new(); |
| if (gcm->ctx == NULL) { |
| srtp_crypto_free(gcm); |
| srtp_crypto_free(*c); |
| *c = NULL; |
| return srtp_err_status_alloc_fail; |
| } |
| |
| /* set pointers */ |
| (*c)->state = gcm; |
| |
| /* setup cipher attributes */ |
| switch (key_len) { |
| case SRTP_AES_GCM_128_KEY_LEN_WSALT: |
| (*c)->type = &srtp_aes_gcm_128; |
| (*c)->algorithm = SRTP_AES_GCM_128; |
| gcm->key_size = SRTP_AES_128_KEY_LEN; |
| gcm->tag_len = tlen; |
| break; |
| case SRTP_AES_GCM_256_KEY_LEN_WSALT: |
| (*c)->type = &srtp_aes_gcm_256; |
| (*c)->algorithm = SRTP_AES_GCM_256; |
| gcm->key_size = SRTP_AES_256_KEY_LEN; |
| gcm->tag_len = tlen; |
| break; |
| } |
| |
| /* set key size */ |
| (*c)->key_len = key_len; |
| |
| return (srtp_err_status_ok); |
| } |
| |
| /* |
| * This function deallocates a GCM session |
| */ |
| static srtp_err_status_t srtp_aes_gcm_openssl_dealloc(srtp_cipher_t *c) |
| { |
| srtp_aes_gcm_ctx_t *ctx; |
| |
| ctx = (srtp_aes_gcm_ctx_t *)c->state; |
| if (ctx) { |
| EVP_CIPHER_CTX_free(ctx->ctx); |
| /* zeroize the key material */ |
| octet_string_set_to_zero(ctx, sizeof(srtp_aes_gcm_ctx_t)); |
| srtp_crypto_free(ctx); |
| } |
| |
| /* free memory */ |
| srtp_crypto_free(c); |
| |
| return (srtp_err_status_ok); |
| } |
| |
| /* |
| * aes_gcm_openssl_context_init(...) initializes the aes_gcm_context |
| * using the value in key[]. |
| * |
| * the key is the secret key |
| */ |
| static srtp_err_status_t srtp_aes_gcm_openssl_context_init(void *cv, |
| const uint8_t *key) |
| { |
| srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv; |
| const EVP_CIPHER *evp; |
| |
| c->dir = srtp_direction_any; |
| |
| debug_print(srtp_mod_aes_gcm, "key: %s", |
| srtp_octet_string_hex_string(key, c->key_size)); |
| |
| switch (c->key_size) { |
| case SRTP_AES_256_KEY_LEN: |
| evp = EVP_aes_256_gcm(); |
| break; |
| case SRTP_AES_128_KEY_LEN: |
| evp = EVP_aes_128_gcm(); |
| break; |
| default: |
| return (srtp_err_status_bad_param); |
| break; |
| } |
| |
| EVP_CIPHER_CTX_reset(c->ctx); |
| |
| if (!EVP_CipherInit_ex(c->ctx, evp, NULL, key, NULL, 0)) { |
| return (srtp_err_status_init_fail); |
| } |
| |
| if (!EVP_CIPHER_CTX_ctrl(c->ctx, EVP_CTRL_GCM_SET_IVLEN, 12, 0)) { |
| return (srtp_err_status_init_fail); |
| } |
| |
| return (srtp_err_status_ok); |
| } |
| |
| /* |
| * aes_gcm_openssl_set_iv(c, iv) sets the counter value to the exor of iv with |
| * the offset |
| */ |
| static srtp_err_status_t srtp_aes_gcm_openssl_set_iv( |
| void *cv, |
| uint8_t *iv, |
| srtp_cipher_direction_t direction) |
| { |
| srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv; |
| |
| if (direction != srtp_direction_encrypt && |
| direction != srtp_direction_decrypt) { |
| return (srtp_err_status_bad_param); |
| } |
| c->dir = direction; |
| |
| debug_print(srtp_mod_aes_gcm, "setting iv: %s", |
| srtp_octet_string_hex_string(iv, 12)); |
| |
| if (!EVP_CipherInit_ex(c->ctx, NULL, NULL, NULL, iv, |
| (c->dir == srtp_direction_encrypt ? 1 : 0))) { |
| return (srtp_err_status_init_fail); |
| } |
| |
| return (srtp_err_status_ok); |
| } |
| |
| /* |
| * This function processes the AAD |
| * |
| * Parameters: |
| * c Crypto context |
| * aad Additional data to process for AEAD cipher suites |
| * aad_len length of aad buffer |
| */ |
| static srtp_err_status_t srtp_aes_gcm_openssl_set_aad(void *cv, |
| const uint8_t *aad, |
| uint32_t aad_len) |
| { |
| srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv; |
| int rv; |
| |
| debug_print(srtp_mod_aes_gcm, "setting AAD: %s", |
| srtp_octet_string_hex_string(aad, aad_len)); |
| |
| /* |
| * EVP_CTRL_GCM_SET_TAG can only be used when decrypting |
| */ |
| if (c->dir == srtp_direction_decrypt) { |
| /* |
| * Set dummy tag, OpenSSL requires the Tag to be set before |
| * processing AAD |
| */ |
| |
| /* |
| * OpenSSL never write to address pointed by the last parameter of |
| * EVP_CIPHER_CTX_ctrl while EVP_CTRL_GCM_SET_TAG (in reality, |
| * OpenSSL copy its content to the context), so we can make |
| * aad read-only in this function and all its wrappers. |
| */ |
| unsigned char dummy_tag[GCM_AUTH_TAG_LEN]; |
| memset(dummy_tag, 0x0, GCM_AUTH_TAG_LEN); |
| if (!EVP_CIPHER_CTX_ctrl(c->ctx, EVP_CTRL_GCM_SET_TAG, c->tag_len, |
| &dummy_tag)) { |
| return (srtp_err_status_algo_fail); |
| } |
| } |
| |
| rv = EVP_Cipher(c->ctx, NULL, aad, aad_len); |
| if (rv < 0 || (uint32_t)rv != aad_len) { |
| return (srtp_err_status_algo_fail); |
| } else { |
| return (srtp_err_status_ok); |
| } |
| } |
| |
| /* |
| * This function encrypts a buffer using AES GCM mode |
| * |
| * Parameters: |
| * c Crypto context |
| * buf data to encrypt |
| * enc_len length of encrypt buffer |
| */ |
| static srtp_err_status_t srtp_aes_gcm_openssl_encrypt(void *cv, |
| unsigned char *buf, |
| unsigned int *enc_len) |
| { |
| srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv; |
| if (c->dir != srtp_direction_encrypt && c->dir != srtp_direction_decrypt) { |
| return (srtp_err_status_bad_param); |
| } |
| |
| /* |
| * Encrypt the data |
| */ |
| EVP_Cipher(c->ctx, buf, buf, *enc_len); |
| |
| return (srtp_err_status_ok); |
| } |
| |
| /* |
| * This function calculates and returns the GCM tag for a given context. |
| * This should be called after encrypting the data. The *len value |
| * is increased by the tag size. The caller must ensure that *buf has |
| * enough room to accept the appended tag. |
| * |
| * Parameters: |
| * c Crypto context |
| * buf data to encrypt |
| * len length of encrypt buffer |
| */ |
| static srtp_err_status_t srtp_aes_gcm_openssl_get_tag(void *cv, |
| uint8_t *buf, |
| uint32_t *len) |
| { |
| srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv; |
| /* |
| * Calculate the tag |
| */ |
| EVP_Cipher(c->ctx, NULL, NULL, 0); |
| |
| /* |
| * Retreive the tag |
| */ |
| if (!EVP_CIPHER_CTX_ctrl(c->ctx, EVP_CTRL_GCM_GET_TAG, c->tag_len, buf)) { |
| return (srtp_err_status_algo_fail); |
| } |
| |
| /* |
| * Increase encryption length by desired tag size |
| */ |
| *len = c->tag_len; |
| |
| return (srtp_err_status_ok); |
| } |
| |
| /* |
| * This function decrypts a buffer using AES GCM mode |
| * |
| * Parameters: |
| * c Crypto context |
| * buf data to encrypt |
| * enc_len length of encrypt buffer |
| */ |
| static srtp_err_status_t srtp_aes_gcm_openssl_decrypt(void *cv, |
| unsigned char *buf, |
| unsigned int *enc_len) |
| { |
| srtp_aes_gcm_ctx_t *c = (srtp_aes_gcm_ctx_t *)cv; |
| if (c->dir != srtp_direction_encrypt && c->dir != srtp_direction_decrypt) { |
| return (srtp_err_status_bad_param); |
| } |
| |
| /* |
| * Set the tag before decrypting |
| */ |
| if (!EVP_CIPHER_CTX_ctrl(c->ctx, EVP_CTRL_GCM_SET_TAG, c->tag_len, |
| buf + (*enc_len - c->tag_len))) { |
| return (srtp_err_status_auth_fail); |
| } |
| EVP_Cipher(c->ctx, buf, buf, *enc_len - c->tag_len); |
| |
| /* |
| * Check the tag |
| */ |
| if (EVP_Cipher(c->ctx, NULL, NULL, 0)) { |
| return (srtp_err_status_auth_fail); |
| } |
| |
| /* |
| * Reduce the buffer size by the tag length since the tag |
| * is not part of the original payload |
| */ |
| *enc_len -= c->tag_len; |
| |
| return (srtp_err_status_ok); |
| } |
| |
| /* |
| * Name of this crypto engine |
| */ |
| static const char srtp_aes_gcm_128_openssl_description[] = |
| "AES-128 GCM using openssl"; |
| static const char srtp_aes_gcm_256_openssl_description[] = |
| "AES-256 GCM using openssl"; |
| |
| /* |
| * This is the vector function table for this crypto engine. |
| */ |
| const srtp_cipher_type_t srtp_aes_gcm_128 = { |
| srtp_aes_gcm_openssl_alloc, |
| srtp_aes_gcm_openssl_dealloc, |
| srtp_aes_gcm_openssl_context_init, |
| srtp_aes_gcm_openssl_set_aad, |
| srtp_aes_gcm_openssl_encrypt, |
| srtp_aes_gcm_openssl_decrypt, |
| srtp_aes_gcm_openssl_set_iv, |
| srtp_aes_gcm_openssl_get_tag, |
| srtp_aes_gcm_128_openssl_description, |
| &srtp_aes_gcm_128_test_case_0, |
| SRTP_AES_GCM_128 |
| }; |
| |
| /* |
| * This is the vector function table for this crypto engine. |
| */ |
| const srtp_cipher_type_t srtp_aes_gcm_256 = { |
| srtp_aes_gcm_openssl_alloc, |
| srtp_aes_gcm_openssl_dealloc, |
| srtp_aes_gcm_openssl_context_init, |
| srtp_aes_gcm_openssl_set_aad, |
| srtp_aes_gcm_openssl_encrypt, |
| srtp_aes_gcm_openssl_decrypt, |
| srtp_aes_gcm_openssl_set_iv, |
| srtp_aes_gcm_openssl_get_tag, |
| srtp_aes_gcm_256_openssl_description, |
| &srtp_aes_gcm_256_test_case_0, |
| SRTP_AES_GCM_256 |
| }; |
