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-rw-r--r--third_party/libsrtp/src/crypto/cipher/aes_icm.c433
1 files changed, 433 insertions, 0 deletions
diff --git a/third_party/libsrtp/src/crypto/cipher/aes_icm.c b/third_party/libsrtp/src/crypto/cipher/aes_icm.c
new file mode 100644
index 0000000000..e05d9e45a3
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+++ b/third_party/libsrtp/src/crypto/cipher/aes_icm.c
@@ -0,0 +1,433 @@
+/*
+ * aes_icm.c
+ *
+ * AES Integer Counter Mode
+ *
+ * David A. McGrew
+ * Cisco Systems, Inc.
+ */
+
+/*
+ *
+ * Copyright (c) 2001-2017 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
+
+#define ALIGN_32 0
+
+#include "aes_icm.h"
+#include "alloc.h"
+#include "cipher_types.h"
+#include "cipher_test_cases.h"
+
+srtp_debug_module_t srtp_mod_aes_icm = {
+ 0, /* debugging is off by default */
+ "aes icm" /* printable module name */
+};
+
+/*
+ * integer counter mode works as follows:
+ *
+ * 16 bits
+ * <----->
+ * +------+------+------+------+------+------+------+------+
+ * | nonce | pakcet index | ctr |---+
+ * +------+------+------+------+------+------+------+------+ |
+ * |
+ * +------+------+------+------+------+------+------+------+ v
+ * | salt |000000|->(+)
+ * +------+------+------+------+------+------+------+------+ |
+ * |
+ * +---------+
+ * | encrypt |
+ * +---------+
+ * |
+ * +------+------+------+------+------+------+------+------+ |
+ * | keystream block |<--+
+ * +------+------+------+------+------+------+------+------+
+ *
+ * All fields are big-endian
+ *
+ * ctr is the block counter, which increments from zero for
+ * each packet (16 bits wide)
+ *
+ * packet index is distinct for each packet (48 bits wide)
+ *
+ * nonce can be distinct across many uses of the same key, or
+ * can be a fixed value per key, or can be per-packet randomness
+ * (64 bits)
+ *
+ */
+
+static srtp_err_status_t srtp_aes_icm_alloc(srtp_cipher_t **c,
+ int key_len,
+ int tlen)
+{
+ srtp_aes_icm_ctx_t *icm;
+
+ debug_print(srtp_mod_aes_icm, "allocating cipher with key length %d",
+ key_len);
+
+ /*
+ * The check for key_len = 30/46 does not apply. Our usage
+ * of aes functions with key_len = values other than 30
+ * has not broken anything. Don't know what would be the
+ * effect of skipping this check for srtp in general.
+ */
+ if (key_len != SRTP_AES_ICM_128_KEY_LEN_WSALT &&
+ key_len != SRTP_AES_ICM_256_KEY_LEN_WSALT) {
+ return srtp_err_status_bad_param;
+ }
+
+ /* allocate memory a cipher of type aes_icm */
+ *c = (srtp_cipher_t *)srtp_crypto_alloc(sizeof(srtp_cipher_t));
+ if (*c == NULL) {
+ return srtp_err_status_alloc_fail;
+ }
+
+ icm = (srtp_aes_icm_ctx_t *)srtp_crypto_alloc(sizeof(srtp_aes_icm_ctx_t));
+ if (icm == NULL) {
+ srtp_crypto_free(*c);
+ *c = NULL;
+ return srtp_err_status_alloc_fail;
+ }
+
+ /* set pointers */
+ (*c)->state = icm;
+
+ switch (key_len) {
+ case SRTP_AES_ICM_256_KEY_LEN_WSALT:
+ (*c)->algorithm = SRTP_AES_ICM_256;
+ (*c)->type = &srtp_aes_icm_256;
+ break;
+ default:
+ (*c)->algorithm = SRTP_AES_ICM_128;
+ (*c)->type = &srtp_aes_icm_128;
+ break;
+ }
+
+ /* set key size */
+ icm->key_size = key_len;
+ (*c)->key_len = key_len;
+
+ return srtp_err_status_ok;
+}
+
+static srtp_err_status_t srtp_aes_icm_dealloc(srtp_cipher_t *c)
+{
+ srtp_aes_icm_ctx_t *ctx;
+
+ if (c == NULL) {
+ return srtp_err_status_bad_param;
+ }
+
+ ctx = (srtp_aes_icm_ctx_t *)c->state;
+ if (ctx) {
+ /* zeroize the key material */
+ octet_string_set_to_zero(ctx, sizeof(srtp_aes_icm_ctx_t));
+ srtp_crypto_free(ctx);
+ }
+
+ /* free the cipher context */
+ srtp_crypto_free(c);
+
+ return srtp_err_status_ok;
+}
+
+/*
+ * aes_icm_context_init(...) initializes the aes_icm_context
+ * using the value in key[].
+ *
+ * the key is the secret key
+ *
+ * the salt is unpredictable (but not necessarily secret) data which
+ * randomizes the starting point in the keystream
+ */
+
+static srtp_err_status_t srtp_aes_icm_context_init(void *cv, const uint8_t *key)
+{
+ srtp_aes_icm_ctx_t *c = (srtp_aes_icm_ctx_t *)cv;
+ srtp_err_status_t status;
+ int base_key_len, copy_len;
+
+ if (c->key_size == SRTP_AES_ICM_128_KEY_LEN_WSALT ||
+ c->key_size == SRTP_AES_ICM_256_KEY_LEN_WSALT) {
+ base_key_len = c->key_size - SRTP_SALT_LEN;
+ } else {
+ return srtp_err_status_bad_param;
+ }
+
+ /*
+ * set counter and initial values to 'offset' value, being careful not to
+ * go past the end of the key buffer
+ */
+ v128_set_to_zero(&c->counter);
+ v128_set_to_zero(&c->offset);
+
+ copy_len = c->key_size - base_key_len;
+ /* force last two octets of the offset to be left zero (for srtp
+ * compatibility) */
+ if (copy_len > SRTP_SALT_LEN) {
+ copy_len = SRTP_SALT_LEN;
+ }
+
+ memcpy(&c->counter, key + base_key_len, copy_len);
+ memcpy(&c->offset, key + base_key_len, copy_len);
+
+ debug_print(srtp_mod_aes_icm, "key: %s",
+ srtp_octet_string_hex_string(key, base_key_len));
+ debug_print(srtp_mod_aes_icm, "offset: %s", v128_hex_string(&c->offset));
+
+ /* expand key */
+ status =
+ srtp_aes_expand_encryption_key(key, base_key_len, &c->expanded_key);
+ if (status) {
+ v128_set_to_zero(&c->counter);
+ v128_set_to_zero(&c->offset);
+ return status;
+ }
+
+ /* indicate that the keystream_buffer is empty */
+ c->bytes_in_buffer = 0;
+
+ return srtp_err_status_ok;
+}
+
+/*
+ * aes_icm_set_iv(c, iv) sets the counter value to the exor of iv with
+ * the offset
+ */
+
+static srtp_err_status_t srtp_aes_icm_set_iv(void *cv,
+ uint8_t *iv,
+ srtp_cipher_direction_t direction)
+{
+ srtp_aes_icm_ctx_t *c = (srtp_aes_icm_ctx_t *)cv;
+ v128_t nonce;
+
+ /* set nonce (for alignment) */
+ v128_copy_octet_string(&nonce, iv);
+
+ debug_print(srtp_mod_aes_icm, "setting iv: %s", v128_hex_string(&nonce));
+
+ v128_xor(&c->counter, &c->offset, &nonce);
+
+ debug_print(srtp_mod_aes_icm, "set_counter: %s",
+ v128_hex_string(&c->counter));
+
+ /* indicate that the keystream_buffer is empty */
+ c->bytes_in_buffer = 0;
+
+ return srtp_err_status_ok;
+}
+
+/*
+ * aes_icm_advance(...) refills the keystream_buffer and
+ * advances the block index of the sicm_context forward by one
+ *
+ * this is an internal, hopefully inlined function
+ */
+static void srtp_aes_icm_advance(srtp_aes_icm_ctx_t *c)
+{
+ /* fill buffer with new keystream */
+ v128_copy(&c->keystream_buffer, &c->counter);
+ srtp_aes_encrypt(&c->keystream_buffer, &c->expanded_key);
+ c->bytes_in_buffer = sizeof(v128_t);
+
+ debug_print(srtp_mod_aes_icm, "counter: %s",
+ v128_hex_string(&c->counter));
+ debug_print(srtp_mod_aes_icm, "ciphertext: %s",
+ v128_hex_string(&c->keystream_buffer));
+
+ /* clock counter forward */
+ if (!++(c->counter.v8[15])) {
+ ++(c->counter.v8[14]);
+ }
+}
+
+/*
+ * icm_encrypt deals with the following cases:
+ *
+ * bytes_to_encr < bytes_in_buffer
+ * - add keystream into data
+ *
+ * bytes_to_encr > bytes_in_buffer
+ * - add keystream into data until keystream_buffer is depleted
+ * - loop over blocks, filling keystream_buffer and then
+ * adding keystream into data
+ * - fill buffer then add in remaining (< 16) bytes of keystream
+ */
+
+static srtp_err_status_t srtp_aes_icm_encrypt(void *cv,
+ unsigned char *buf,
+ unsigned int *enc_len)
+{
+ srtp_aes_icm_ctx_t *c = (srtp_aes_icm_ctx_t *)cv;
+ unsigned int bytes_to_encr = *enc_len;
+ unsigned int i;
+ uint32_t *b;
+
+ /* check that there's enough segment left*/
+ if ((bytes_to_encr + htons(c->counter.v16[7])) > 0xffff) {
+ return srtp_err_status_terminus;
+ }
+
+ debug_print(srtp_mod_aes_icm, "block index: %d", htons(c->counter.v16[7]));
+ if (bytes_to_encr <= (unsigned int)c->bytes_in_buffer) {
+ /* deal with odd case of small bytes_to_encr */
+ for (i = (sizeof(v128_t) - c->bytes_in_buffer);
+ i < (sizeof(v128_t) - c->bytes_in_buffer + bytes_to_encr); i++) {
+ *buf++ ^= c->keystream_buffer.v8[i];
+ }
+
+ c->bytes_in_buffer -= bytes_to_encr;
+
+ /* return now to avoid the main loop */
+ return srtp_err_status_ok;
+
+ } else {
+ /* encrypt bytes until the remaining data is 16-byte aligned */
+ for (i = (sizeof(v128_t) - c->bytes_in_buffer); i < sizeof(v128_t);
+ i++) {
+ *buf++ ^= c->keystream_buffer.v8[i];
+ }
+
+ bytes_to_encr -= c->bytes_in_buffer;
+ c->bytes_in_buffer = 0;
+ }
+
+ /* now loop over entire 16-byte blocks of keystream */
+ for (i = 0; i < (bytes_to_encr / sizeof(v128_t)); i++) {
+ /* fill buffer with new keystream */
+ srtp_aes_icm_advance(c);
+
+/*
+ * add keystream into the data buffer (this would be a lot faster
+ * if we could assume 32-bit alignment!)
+ */
+
+#if ALIGN_32
+ b = (uint32_t *)buf;
+ *b++ ^= c->keystream_buffer.v32[0];
+ *b++ ^= c->keystream_buffer.v32[1];
+ *b++ ^= c->keystream_buffer.v32[2];
+ *b++ ^= c->keystream_buffer.v32[3];
+ buf = (uint8_t *)b;
+#else
+ if ((((uintptr_t)buf) & 0x03) != 0) {
+ *buf++ ^= c->keystream_buffer.v8[0];
+ *buf++ ^= c->keystream_buffer.v8[1];
+ *buf++ ^= c->keystream_buffer.v8[2];
+ *buf++ ^= c->keystream_buffer.v8[3];
+ *buf++ ^= c->keystream_buffer.v8[4];
+ *buf++ ^= c->keystream_buffer.v8[5];
+ *buf++ ^= c->keystream_buffer.v8[6];
+ *buf++ ^= c->keystream_buffer.v8[7];
+ *buf++ ^= c->keystream_buffer.v8[8];
+ *buf++ ^= c->keystream_buffer.v8[9];
+ *buf++ ^= c->keystream_buffer.v8[10];
+ *buf++ ^= c->keystream_buffer.v8[11];
+ *buf++ ^= c->keystream_buffer.v8[12];
+ *buf++ ^= c->keystream_buffer.v8[13];
+ *buf++ ^= c->keystream_buffer.v8[14];
+ *buf++ ^= c->keystream_buffer.v8[15];
+ } else {
+ b = (uint32_t *)buf;
+ *b++ ^= c->keystream_buffer.v32[0];
+ *b++ ^= c->keystream_buffer.v32[1];
+ *b++ ^= c->keystream_buffer.v32[2];
+ *b++ ^= c->keystream_buffer.v32[3];
+ buf = (uint8_t *)b;
+ }
+#endif /* #if ALIGN_32 */
+ }
+
+ /* if there is a tail end of the data, process it */
+ if ((bytes_to_encr & 0xf) != 0) {
+ /* fill buffer with new keystream */
+ srtp_aes_icm_advance(c);
+
+ for (i = 0; i < (bytes_to_encr & 0xf); i++) {
+ *buf++ ^= c->keystream_buffer.v8[i];
+ }
+
+ /* reset the keystream buffer size to right value */
+ c->bytes_in_buffer = sizeof(v128_t) - i;
+ } else {
+ /* no tail, so just reset the keystream buffer size to zero */
+ c->bytes_in_buffer = 0;
+ }
+
+ return srtp_err_status_ok;
+}
+
+static const char srtp_aes_icm_128_description[] =
+ "AES-128 integer counter mode";
+static const char srtp_aes_icm_256_description[] =
+ "AES-256 integer counter mode";
+
+/*
+ * note: the encrypt function is identical to the decrypt function
+ */
+
+const srtp_cipher_type_t srtp_aes_icm_128 = {
+ srtp_aes_icm_alloc, /* */
+ srtp_aes_icm_dealloc, /* */
+ srtp_aes_icm_context_init, /* */
+ 0, /* set_aad */
+ srtp_aes_icm_encrypt, /* */
+ srtp_aes_icm_encrypt, /* */
+ srtp_aes_icm_set_iv, /* */
+ 0, /* get_tag */
+ srtp_aes_icm_128_description, /* */
+ &srtp_aes_icm_128_test_case_0, /* */
+ SRTP_AES_ICM_128 /* */
+};
+
+const srtp_cipher_type_t srtp_aes_icm_256 = {
+ srtp_aes_icm_alloc, /* */
+ srtp_aes_icm_dealloc, /* */
+ srtp_aes_icm_context_init, /* */
+ 0, /* set_aad */
+ srtp_aes_icm_encrypt, /* */
+ srtp_aes_icm_encrypt, /* */
+ srtp_aes_icm_set_iv, /* */
+ 0, /* get_tag */
+ srtp_aes_icm_256_description, /* */
+ &srtp_aes_icm_256_test_case_0, /* */
+ SRTP_AES_ICM_256 /* */
+};
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