/*
* cipher.c
*
* cipher meta-functions
*
* 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
#include "cipher.h"
#include "crypto_types.h"
#include "err.h" /* for srtp_debug */
#include "alloc.h" /* for crypto_alloc(), crypto_free() */
srtp_debug_module_t srtp_mod_cipher = {
0, /* debugging is off by default */
"cipher" /* printable module name */
};
srtp_err_status_t srtp_cipher_type_alloc (const srtp_cipher_type_t *ct, srtp_cipher_t **c, int key_len, int tlen)
{
if (!ct || !ct->alloc) {
return (srtp_err_status_bad_param);
}
return ((ct)->alloc((c), (key_len), (tlen)));
}
srtp_err_status_t srtp_cipher_dealloc (srtp_cipher_t *c)
{
if (!c || !c->type) {
return (srtp_err_status_bad_param);
}
return (((c)->type)->dealloc(c));
}
srtp_err_status_t srtp_cipher_init (srtp_cipher_t *c, const uint8_t *key)
{
if (!c || !c->type || !c->state) {
return (srtp_err_status_bad_param);
}
return (((c)->type)->init(((c)->state), (key)));
}
srtp_err_status_t srtp_cipher_set_iv (srtp_cipher_t *c, uint8_t *iv, int direction)
{
if (!c || !c->type || !c->state) {
return (srtp_err_status_bad_param);
}
return (((c)->type)->set_iv(((c)->state), iv, direction));
}
srtp_err_status_t srtp_cipher_output (srtp_cipher_t *c, uint8_t *buffer, uint32_t *num_octets_to_output)
{
/* zeroize the buffer */
octet_string_set_to_zero(buffer, *num_octets_to_output);
/* exor keystream into buffer */
return (((c)->type)->encrypt(((c)->state), buffer, num_octets_to_output));
}
srtp_err_status_t srtp_cipher_encrypt (srtp_cipher_t *c, uint8_t *buffer, uint32_t *num_octets_to_output)
{
if (!c || !c->type || !c->state) {
return (srtp_err_status_bad_param);
}
return (((c)->type)->encrypt(((c)->state), buffer, num_octets_to_output));
}
srtp_err_status_t srtp_cipher_decrypt (srtp_cipher_t *c, uint8_t *buffer, uint32_t *num_octets_to_output)
{
if (!c || !c->type || !c->state) {
return (srtp_err_status_bad_param);
}
return (((c)->type)->decrypt(((c)->state), buffer, num_octets_to_output));
}
srtp_err_status_t srtp_cipher_get_tag (srtp_cipher_t *c, uint8_t *buffer, uint32_t *tag_len)
{
if (!c || !c->type || !c->state) {
return (srtp_err_status_bad_param);
}
if (!((c)->type)->get_tag) {
return (srtp_err_status_no_such_op);
}
return (((c)->type)->get_tag(((c)->state), buffer, tag_len));
}
srtp_err_status_t srtp_cipher_set_aad (srtp_cipher_t *c, const uint8_t *aad, uint32_t aad_len)
{
if (!c || !c->type || !c->state) {
return (srtp_err_status_bad_param);
}
if (!((c)->type)->set_aad) {
return (srtp_err_status_no_such_op);
}
return (((c)->type)->set_aad(((c)->state), aad, aad_len));
}
/* some bookkeeping functions */
int srtp_cipher_get_key_length (const srtp_cipher_t *c)
{
return c->key_len;
}
/*
* A trivial platform independent random source. The random
* data is used for some of the cipher self-tests.
*/
static srtp_err_status_t srtp_cipher_rand (void *dest, uint32_t len)
{
#if defined(HAVE_RAND_S)
uint8_t *dst = (uint8_t *)dest;
while (len)
{
unsigned int val;
errno_t err = rand_s(&val);
if (err != 0)
return srtp_err_status_fail;
*dst++ = val & 0xff;
len--;
}
#else
/* Generic C-library (rand()) version */
/* This is a random source of last resort */
uint8_t *dst = (uint8_t *)dest;
while (len)
{
int val = rand();
/* rand() returns 0-32767 (ugh) */
/* Is this a good enough way to get random bytes?
It is if it passes FIPS-140... */
*dst++ = val & 0xff;
len--;
}
#endif
return srtp_err_status_ok;
}
#define SELF_TEST_BUF_OCTETS 128
#define NUM_RAND_TESTS 128
#define MAX_KEY_LEN 64
/*
* srtp_cipher_type_test(ct, test_data) tests a cipher of type ct against
* test cases provided in a list test_data of values of key, salt, iv,
* plaintext, and ciphertext that is known to be good
*/
srtp_err_status_t srtp_cipher_type_test (const srtp_cipher_type_t *ct, const srtp_cipher_test_case_t *test_data)
{
const srtp_cipher_test_case_t *test_case = test_data;
srtp_cipher_t *c;
srtp_err_status_t status;
uint8_t buffer[SELF_TEST_BUF_OCTETS];
uint8_t buffer2[SELF_TEST_BUF_OCTETS];
uint32_t tag_len;
unsigned int len;
int i, j, case_num = 0;
debug_print(srtp_mod_cipher, "running self-test for cipher %s",
ct->description);
/*
* check to make sure that we have at least one test case, and
* return an error if we don't - we need to be paranoid here
*/
if (test_case == NULL) {
return srtp_err_status_cant_check;
}
/*
* loop over all test cases, perform known-answer tests of both the
* encryption and decryption functions
*/
while (test_case != NULL) {
/* allocate cipher */
status = srtp_cipher_type_alloc(ct, &c, test_case->key_length_octets, test_case->tag_length_octets);
if (status) {
return status;
}
/*
* test the encrypt function
*/
debug_print(srtp_mod_cipher, "testing encryption", NULL);
/* initialize cipher */
status = srtp_cipher_init(c, test_case->key);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
/* copy plaintext into test buffer */
if (test_case->ciphertext_length_octets > SELF_TEST_BUF_OCTETS) {
srtp_cipher_dealloc(c);
return srtp_err_status_bad_param;
}
for (i = 0; i < test_case->plaintext_length_octets; i++) {
buffer[i] = test_case->plaintext[i];
}
debug_print(srtp_mod_cipher, "plaintext: %s",
srtp_octet_string_hex_string(buffer,
test_case->plaintext_length_octets));
/* set the initialization vector */
status = srtp_cipher_set_iv(c, (uint8_t*)test_case->idx, srtp_direction_encrypt);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
if (c->algorithm == SRTP_AES_GCM_128 || c->algorithm == SRTP_AES_GCM_256) {
debug_print(srtp_mod_cipher, "IV: %s",
srtp_octet_string_hex_string(test_case->idx, 12));
/*
* Set the AAD
*/
status = srtp_cipher_set_aad(c, test_case->aad, test_case->aad_length_octets);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
debug_print(srtp_mod_cipher, "AAD: %s",
srtp_octet_string_hex_string(test_case->aad,
test_case->aad_length_octets));
}
/* encrypt */
len = test_case->plaintext_length_octets;
status = srtp_cipher_encrypt(c, buffer, &len);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
if (c->algorithm == SRTP_AES_GCM_128 || c->algorithm == SRTP_AES_GCM_256) {
/*
* Get the GCM tag
*/
status = srtp_cipher_get_tag(c, buffer + len, &tag_len);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
len += tag_len;
}
debug_print(srtp_mod_cipher, "ciphertext: %s",
srtp_octet_string_hex_string(buffer,
test_case->ciphertext_length_octets));
/* compare the resulting ciphertext with that in the test case */
if (len != test_case->ciphertext_length_octets) {
srtp_cipher_dealloc(c);
return srtp_err_status_algo_fail;
}
status = srtp_err_status_ok;
for (i = 0; i < test_case->ciphertext_length_octets; i++) {
if (buffer[i] != test_case->ciphertext[i]) {
status = srtp_err_status_algo_fail;
debug_print(srtp_mod_cipher, "test case %d failed", case_num);
debug_print(srtp_mod_cipher, "(failure at byte %d)", i);
break;
}
}
if (status) {
debug_print(srtp_mod_cipher, "c computed: %s",
srtp_octet_string_hex_string(buffer,
2 * test_case->plaintext_length_octets));
debug_print(srtp_mod_cipher, "c expected: %s",
srtp_octet_string_hex_string(test_case->ciphertext,
2 * test_case->plaintext_length_octets));
srtp_cipher_dealloc(c);
return srtp_err_status_algo_fail;
}
/*
* test the decrypt function
*/
debug_print(srtp_mod_cipher, "testing decryption", NULL);
/* re-initialize cipher for decryption */
status = srtp_cipher_init(c, test_case->key);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
/* copy ciphertext into test buffer */
if (test_case->ciphertext_length_octets > SELF_TEST_BUF_OCTETS) {
srtp_cipher_dealloc(c);
return srtp_err_status_bad_param;
}
for (i = 0; i < test_case->ciphertext_length_octets; i++) {
buffer[i] = test_case->ciphertext[i];
}
debug_print(srtp_mod_cipher, "ciphertext: %s",
srtp_octet_string_hex_string(buffer,
test_case->plaintext_length_octets));
/* set the initialization vector */
status = srtp_cipher_set_iv(c, (uint8_t*)test_case->idx, srtp_direction_decrypt);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
if (c->algorithm == SRTP_AES_GCM_128 || c->algorithm == SRTP_AES_GCM_256) {
/*
* Set the AAD
*/
status = srtp_cipher_set_aad(c, test_case->aad, test_case->aad_length_octets);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
debug_print(srtp_mod_cipher, "AAD: %s",
srtp_octet_string_hex_string(test_case->aad,
test_case->aad_length_octets));
}
/* decrypt */
len = test_case->ciphertext_length_octets;
status = srtp_cipher_decrypt(c, buffer, &len);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
debug_print(srtp_mod_cipher, "plaintext: %s",
srtp_octet_string_hex_string(buffer,
test_case->plaintext_length_octets));
/* compare the resulting plaintext with that in the test case */
if (len != test_case->plaintext_length_octets) {
srtp_cipher_dealloc(c);
return srtp_err_status_algo_fail;
}
status = srtp_err_status_ok;
for (i = 0; i < test_case->plaintext_length_octets; i++) {
if (buffer[i] != test_case->plaintext[i]) {
status = srtp_err_status_algo_fail;
debug_print(srtp_mod_cipher, "test case %d failed", case_num);
debug_print(srtp_mod_cipher, "(failure at byte %d)", i);
}
}
if (status) {
debug_print(srtp_mod_cipher, "p computed: %s",
srtp_octet_string_hex_string(buffer,
2 * test_case->plaintext_length_octets));
debug_print(srtp_mod_cipher, "p expected: %s",
srtp_octet_string_hex_string(test_case->plaintext,
2 * test_case->plaintext_length_octets));
srtp_cipher_dealloc(c);
return srtp_err_status_algo_fail;
}
/* deallocate the cipher */
status = srtp_cipher_dealloc(c);
if (status) {
return status;
}
/*
* the cipher passed the test case, so move on to the next test
* case in the list; if NULL, we'l proceed to the next test
*/
test_case = test_case->next_test_case;
++case_num;
}
/* now run some random invertibility tests */
/* allocate cipher, using paramaters from the first test case */
test_case = test_data;
status = srtp_cipher_type_alloc(ct, &c, test_case->key_length_octets, test_case->tag_length_octets);
if (status) {
return status;
}
for (j = 0; j < NUM_RAND_TESTS; j++) {
unsigned length;
int plaintext_len;
uint8_t key[MAX_KEY_LEN];
uint8_t iv[MAX_KEY_LEN];
/* choose a length at random (leaving room for IV and padding) */
length = rand() % (SELF_TEST_BUF_OCTETS - 64);
debug_print(srtp_mod_cipher, "random plaintext length %d\n", length);
status = srtp_cipher_rand(buffer, length);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
debug_print(srtp_mod_cipher, "plaintext: %s",
srtp_octet_string_hex_string(buffer, length));
/* copy plaintext into second buffer */
for (i = 0; (unsigned int)i < length; i++) {
buffer2[i] = buffer[i];
}
/* choose a key at random */
if (test_case->key_length_octets > MAX_KEY_LEN) {
srtp_cipher_dealloc(c);
return srtp_err_status_cant_check;
}
status = srtp_cipher_rand(key, test_case->key_length_octets);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
/* chose a random initialization vector */
status = srtp_cipher_rand(iv, MAX_KEY_LEN);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
/* initialize cipher */
status = srtp_cipher_init(c, key);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
/* set initialization vector */
status = srtp_cipher_set_iv(c, (uint8_t*)test_case->idx, srtp_direction_encrypt);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
if (c->algorithm == SRTP_AES_GCM_128 || c->algorithm == SRTP_AES_GCM_256) {
/*
* Set the AAD
*/
status = srtp_cipher_set_aad(c, test_case->aad, test_case->aad_length_octets);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
debug_print(srtp_mod_cipher, "AAD: %s",
srtp_octet_string_hex_string(test_case->aad,
test_case->aad_length_octets));
}
/* encrypt buffer with cipher */
plaintext_len = length;
status = srtp_cipher_encrypt(c, buffer, &length);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
if (c->algorithm == SRTP_AES_GCM_128 || c->algorithm == SRTP_AES_GCM_256) {
/*
* Get the GCM tag
*/
status = srtp_cipher_get_tag(c, buffer + length, &tag_len);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
length += tag_len;
}
debug_print(srtp_mod_cipher, "ciphertext: %s",
srtp_octet_string_hex_string(buffer, length));
/*
* re-initialize cipher for decryption, re-set the iv, then
* decrypt the ciphertext
*/
status = srtp_cipher_init(c, key);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
status = srtp_cipher_set_iv(c, (uint8_t*)test_case->idx, srtp_direction_decrypt);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
if (c->algorithm == SRTP_AES_GCM_128 || c->algorithm == SRTP_AES_GCM_256) {
/*
* Set the AAD
*/
status = srtp_cipher_set_aad(c, test_case->aad, test_case->aad_length_octets);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
debug_print(srtp_mod_cipher, "AAD: %s",
srtp_octet_string_hex_string(test_case->aad,
test_case->aad_length_octets));
}
status = srtp_cipher_decrypt(c, buffer, &length);
if (status) {
srtp_cipher_dealloc(c);
return status;
}
debug_print(srtp_mod_cipher, "plaintext[2]: %s",
srtp_octet_string_hex_string(buffer, length));
/* compare the resulting plaintext with the original one */
if (length != plaintext_len) {
srtp_cipher_dealloc(c);
return srtp_err_status_algo_fail;
}
status = srtp_err_status_ok;
for (i = 0; i < plaintext_len; i++) {
if (buffer[i] != buffer2[i]) {
status = srtp_err_status_algo_fail;
debug_print(srtp_mod_cipher, "random test case %d failed", case_num);
debug_print(srtp_mod_cipher, "(failure at byte %d)", i);
}
}
if (status) {
srtp_cipher_dealloc(c);
return srtp_err_status_algo_fail;
}
}
status = srtp_cipher_dealloc(c);
if (status) {
return status;
}
return srtp_err_status_ok;
}
/*
* srtp_cipher_type_self_test(ct) performs srtp_cipher_type_test on ct's internal
* list of test data.
*/
srtp_err_status_t srtp_cipher_type_self_test (const srtp_cipher_type_t *ct)
{
return srtp_cipher_type_test(ct, ct->test_data);
}
/*
* cipher_bits_per_second(c, l, t) computes (an estimate of) the
* number of bits that a cipher implementation can encrypt in a second
*
* c is a cipher (which MUST be allocated and initialized already), l
* is the length in octets of the test data to be encrypted, and t is
* the number of trials
*
* if an error is encountered, the value 0 is returned
*/
uint64_t srtp_cipher_bits_per_second (srtp_cipher_t *c, int octets_in_buffer, int num_trials)
{
int i;
v128_t nonce;
clock_t timer;
unsigned char *enc_buf;
unsigned int len = octets_in_buffer;
enc_buf = (unsigned char*)srtp_crypto_alloc(octets_in_buffer);
if (enc_buf == NULL) {
return 0; /* indicate bad parameters by returning null */
}
/* time repeated trials */
v128_set_to_zero(&nonce);
timer = clock();
for (i = 0; i < num_trials; i++, nonce.v32[3] = i) {
if (srtp_cipher_set_iv(c, (uint8_t*)&nonce, srtp_direction_encrypt) != srtp_err_status_ok) {
srtp_crypto_free(enc_buf);
return 0;
}
if (srtp_cipher_encrypt(c, enc_buf, &len) != srtp_err_status_ok) {
srtp_crypto_free(enc_buf);
return 0;
}
}
timer = clock() - timer;
srtp_crypto_free(enc_buf);
if (timer == 0) {
/* Too fast! */
return 0;
}
return (uint64_t)CLOCKS_PER_SEC * num_trials * 8 * octets_in_buffer / timer;
}