mbedtls/library/ccm.c
Dave Rodgman e3c05853d6 Header updates
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
2023-11-03 12:21:36 +00:00

712 lines
22 KiB
C

/*
* NIST SP800-38C compliant CCM implementation
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
/*
* Definition of CCM:
* http://csrc.nist.gov/publications/nistpubs/800-38C/SP800-38C_updated-July20_2007.pdf
* RFC 3610 "Counter with CBC-MAC (CCM)"
*
* Related:
* RFC 5116 "An Interface and Algorithms for Authenticated Encryption"
*/
#include "common.h"
#if defined(MBEDTLS_CCM_C)
#include "mbedtls/ccm.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include "mbedtls/constant_time.h"
#include <string.h>
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
#include <stdio.h>
#define mbedtls_printf printf
#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
#endif /* MBEDTLS_PLATFORM_C */
#if !defined(MBEDTLS_CCM_ALT)
/*
* Initialize context
*/
void mbedtls_ccm_init(mbedtls_ccm_context *ctx)
{
memset(ctx, 0, sizeof(mbedtls_ccm_context));
}
int mbedtls_ccm_setkey(mbedtls_ccm_context *ctx,
mbedtls_cipher_id_t cipher,
const unsigned char *key,
unsigned int keybits)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
const mbedtls_cipher_info_t *cipher_info;
cipher_info = mbedtls_cipher_info_from_values(cipher, keybits,
MBEDTLS_MODE_ECB);
if (cipher_info == NULL) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
if (mbedtls_cipher_info_get_block_size(cipher_info) != 16) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
mbedtls_cipher_free(&ctx->cipher_ctx);
if ((ret = mbedtls_cipher_setup(&ctx->cipher_ctx, cipher_info)) != 0) {
return ret;
}
if ((ret = mbedtls_cipher_setkey(&ctx->cipher_ctx, key, keybits,
MBEDTLS_ENCRYPT)) != 0) {
return ret;
}
return 0;
}
/*
* Free context
*/
void mbedtls_ccm_free(mbedtls_ccm_context *ctx)
{
if (ctx == NULL) {
return;
}
mbedtls_cipher_free(&ctx->cipher_ctx);
mbedtls_platform_zeroize(ctx, sizeof(mbedtls_ccm_context));
}
#define CCM_STATE__CLEAR 0
#define CCM_STATE__STARTED (1 << 0)
#define CCM_STATE__LENGTHS_SET (1 << 1)
#define CCM_STATE__AUTH_DATA_STARTED (1 << 2)
#define CCM_STATE__AUTH_DATA_FINISHED (1 << 3)
#define CCM_STATE__ERROR (1 << 4)
/*
* Encrypt or decrypt a partial block with CTR
*/
static int mbedtls_ccm_crypt(mbedtls_ccm_context *ctx,
size_t offset, size_t use_len,
const unsigned char *input,
unsigned char *output)
{
size_t olen = 0;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char tmp_buf[16] = { 0 };
if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->ctr, 16, tmp_buf,
&olen)) != 0) {
ctx->state |= CCM_STATE__ERROR;
mbedtls_platform_zeroize(tmp_buf, sizeof(tmp_buf));
return ret;
}
mbedtls_xor(output, input, tmp_buf + offset, use_len);
mbedtls_platform_zeroize(tmp_buf, sizeof(tmp_buf));
return ret;
}
static void mbedtls_ccm_clear_state(mbedtls_ccm_context *ctx)
{
ctx->state = CCM_STATE__CLEAR;
memset(ctx->y, 0, 16);
memset(ctx->ctr, 0, 16);
}
static int ccm_calculate_first_block_if_ready(mbedtls_ccm_context *ctx)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char i;
size_t len_left, olen;
/* length calculation can be done only after both
* mbedtls_ccm_starts() and mbedtls_ccm_set_lengths() have been executed
*/
if (!(ctx->state & CCM_STATE__STARTED) || !(ctx->state & CCM_STATE__LENGTHS_SET)) {
return 0;
}
/* CCM expects non-empty tag.
* CCM* allows empty tag. For CCM* without tag, ignore plaintext length.
*/
if (ctx->tag_len == 0) {
if (ctx->mode == MBEDTLS_CCM_STAR_ENCRYPT || ctx->mode == MBEDTLS_CCM_STAR_DECRYPT) {
ctx->plaintext_len = 0;
} else {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
}
/*
* First block:
* 0 .. 0 flags
* 1 .. iv_len nonce (aka iv) - set by: mbedtls_ccm_starts()
* iv_len+1 .. 15 length
*
* With flags as (bits):
* 7 0
* 6 add present?
* 5 .. 3 (t - 2) / 2
* 2 .. 0 q - 1
*/
ctx->y[0] |= (ctx->add_len > 0) << 6;
ctx->y[0] |= ((ctx->tag_len - 2) / 2) << 3;
ctx->y[0] |= ctx->q - 1;
for (i = 0, len_left = ctx->plaintext_len; i < ctx->q; i++, len_left >>= 8) {
ctx->y[15-i] = MBEDTLS_BYTE_0(len_left);
}
if (len_left > 0) {
ctx->state |= CCM_STATE__ERROR;
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
/* Start CBC-MAC with first block*/
if ((ret = mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen)) != 0) {
ctx->state |= CCM_STATE__ERROR;
return ret;
}
return 0;
}
int mbedtls_ccm_starts(mbedtls_ccm_context *ctx,
int mode,
const unsigned char *iv,
size_t iv_len)
{
/* Also implies q is within bounds */
if (iv_len < 7 || iv_len > 13) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
ctx->mode = mode;
ctx->q = 16 - 1 - (unsigned char) iv_len;
/*
* Prepare counter block for encryption:
* 0 .. 0 flags
* 1 .. iv_len nonce (aka iv)
* iv_len+1 .. 15 counter (initially 1)
*
* With flags as (bits):
* 7 .. 3 0
* 2 .. 0 q - 1
*/
memset(ctx->ctr, 0, 16);
ctx->ctr[0] = ctx->q - 1;
memcpy(ctx->ctr + 1, iv, iv_len);
memset(ctx->ctr + 1 + iv_len, 0, ctx->q);
ctx->ctr[15] = 1;
/*
* See ccm_calculate_first_block_if_ready() for block layout description
*/
memcpy(ctx->y + 1, iv, iv_len);
ctx->state |= CCM_STATE__STARTED;
return ccm_calculate_first_block_if_ready(ctx);
}
int mbedtls_ccm_set_lengths(mbedtls_ccm_context *ctx,
size_t total_ad_len,
size_t plaintext_len,
size_t tag_len)
{
/*
* Check length requirements: SP800-38C A.1
* Additional requirement: a < 2^16 - 2^8 to simplify the code.
* 'length' checked later (when writing it to the first block)
*
* Also, loosen the requirements to enable support for CCM* (IEEE 802.15.4).
*/
if (tag_len == 2 || tag_len > 16 || tag_len % 2 != 0) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
if (total_ad_len >= 0xFF00) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
ctx->plaintext_len = plaintext_len;
ctx->add_len = total_ad_len;
ctx->tag_len = tag_len;
ctx->processed = 0;
ctx->state |= CCM_STATE__LENGTHS_SET;
return ccm_calculate_first_block_if_ready(ctx);
}
int mbedtls_ccm_update_ad(mbedtls_ccm_context *ctx,
const unsigned char *add,
size_t add_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t olen, use_len, offset;
if (ctx->state & CCM_STATE__ERROR) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
if (add_len > 0) {
if (ctx->state & CCM_STATE__AUTH_DATA_FINISHED) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
if (!(ctx->state & CCM_STATE__AUTH_DATA_STARTED)) {
if (add_len > ctx->add_len) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
ctx->y[0] ^= (unsigned char) ((ctx->add_len >> 8) & 0xFF);
ctx->y[1] ^= (unsigned char) ((ctx->add_len) & 0xFF);
ctx->state |= CCM_STATE__AUTH_DATA_STARTED;
} else if (ctx->processed + add_len > ctx->add_len) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
while (add_len > 0) {
offset = (ctx->processed + 2) % 16; /* account for y[0] and y[1]
* holding total auth data length */
use_len = 16 - offset;
if (use_len > add_len) {
use_len = add_len;
}
mbedtls_xor(ctx->y + offset, ctx->y + offset, add, use_len);
ctx->processed += use_len;
add_len -= use_len;
add += use_len;
if (use_len + offset == 16 || ctx->processed == ctx->add_len) {
if ((ret =
mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen)) != 0) {
ctx->state |= CCM_STATE__ERROR;
return ret;
}
}
}
if (ctx->processed == ctx->add_len) {
ctx->state |= CCM_STATE__AUTH_DATA_FINISHED;
ctx->processed = 0; // prepare for mbedtls_ccm_update()
}
}
return 0;
}
int mbedtls_ccm_update(mbedtls_ccm_context *ctx,
const unsigned char *input, size_t input_len,
unsigned char *output, size_t output_size,
size_t *output_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char i;
size_t use_len, offset, olen;
unsigned char local_output[16];
if (ctx->state & CCM_STATE__ERROR) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
/* Check against plaintext length only if performing operation with
* authentication
*/
if (ctx->tag_len != 0 && ctx->processed + input_len > ctx->plaintext_len) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
if (output_size < input_len) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
*output_len = input_len;
ret = 0;
while (input_len > 0) {
offset = ctx->processed % 16;
use_len = 16 - offset;
if (use_len > input_len) {
use_len = input_len;
}
ctx->processed += use_len;
if (ctx->mode == MBEDTLS_CCM_ENCRYPT || \
ctx->mode == MBEDTLS_CCM_STAR_ENCRYPT) {
mbedtls_xor(ctx->y + offset, ctx->y + offset, input, use_len);
if (use_len + offset == 16 || ctx->processed == ctx->plaintext_len) {
if ((ret =
mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen)) != 0) {
ctx->state |= CCM_STATE__ERROR;
goto exit;
}
}
ret = mbedtls_ccm_crypt(ctx, offset, use_len, input, output);
if (ret != 0) {
goto exit;
}
}
if (ctx->mode == MBEDTLS_CCM_DECRYPT || \
ctx->mode == MBEDTLS_CCM_STAR_DECRYPT) {
/* Since output may be in shared memory, we cannot be sure that
* it will contain what we wrote to it. Therefore, we should avoid using
* it as input to any operations.
* Write decrypted data to local_output to avoid using output variable as
* input in the XOR operation for Y.
*/
ret = mbedtls_ccm_crypt(ctx, offset, use_len, input, local_output);
if (ret != 0) {
goto exit;
}
mbedtls_xor(ctx->y + offset, ctx->y + offset, local_output, use_len);
memcpy(output, local_output, use_len);
if (use_len + offset == 16 || ctx->processed == ctx->plaintext_len) {
if ((ret =
mbedtls_cipher_update(&ctx->cipher_ctx, ctx->y, 16, ctx->y, &olen)) != 0) {
ctx->state |= CCM_STATE__ERROR;
goto exit;
}
}
}
if (use_len + offset == 16 || ctx->processed == ctx->plaintext_len) {
for (i = 0; i < ctx->q; i++) {
if (++(ctx->ctr)[15-i] != 0) {
break;
}
}
}
input_len -= use_len;
input += use_len;
output += use_len;
}
exit:
mbedtls_platform_zeroize(local_output, 16);
return ret;
}
int mbedtls_ccm_finish(mbedtls_ccm_context *ctx,
unsigned char *tag, size_t tag_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char i;
if (ctx->state & CCM_STATE__ERROR) {
return MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
}
if (ctx->add_len > 0 && !(ctx->state & CCM_STATE__AUTH_DATA_FINISHED)) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
if (ctx->plaintext_len > 0 && ctx->processed != ctx->plaintext_len) {
return MBEDTLS_ERR_CCM_BAD_INPUT;
}
/*
* Authentication: reset counter and crypt/mask internal tag
*/
for (i = 0; i < ctx->q; i++) {
ctx->ctr[15-i] = 0;
}
ret = mbedtls_ccm_crypt(ctx, 0, 16, ctx->y, ctx->y);
if (ret != 0) {
return ret;
}
if (tag != NULL) {
memcpy(tag, ctx->y, tag_len);
}
mbedtls_ccm_clear_state(ctx);
return 0;
}
/*
* Authenticated encryption or decryption
*/
static int ccm_auth_crypt(mbedtls_ccm_context *ctx, int mode, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
unsigned char *tag, size_t tag_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t olen;
if ((ret = mbedtls_ccm_starts(ctx, mode, iv, iv_len)) != 0) {
return ret;
}
if ((ret = mbedtls_ccm_set_lengths(ctx, add_len, length, tag_len)) != 0) {
return ret;
}
if ((ret = mbedtls_ccm_update_ad(ctx, add, add_len)) != 0) {
return ret;
}
if ((ret = mbedtls_ccm_update(ctx, input, length,
output, length, &olen)) != 0) {
return ret;
}
if ((ret = mbedtls_ccm_finish(ctx, tag, tag_len)) != 0) {
return ret;
}
return 0;
}
/*
* Authenticated encryption
*/
int mbedtls_ccm_star_encrypt_and_tag(mbedtls_ccm_context *ctx, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
unsigned char *tag, size_t tag_len)
{
return ccm_auth_crypt(ctx, MBEDTLS_CCM_STAR_ENCRYPT, length, iv, iv_len,
add, add_len, input, output, tag, tag_len);
}
int mbedtls_ccm_encrypt_and_tag(mbedtls_ccm_context *ctx, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
unsigned char *tag, size_t tag_len)
{
return ccm_auth_crypt(ctx, MBEDTLS_CCM_ENCRYPT, length, iv, iv_len,
add, add_len, input, output, tag, tag_len);
}
/*
* Authenticated decryption
*/
static int mbedtls_ccm_compare_tags(const unsigned char *tag1,
const unsigned char *tag2,
size_t tag_len)
{
/* Check tag in "constant-time" */
int diff = mbedtls_ct_memcmp(tag1, tag2, tag_len);
if (diff != 0) {
return MBEDTLS_ERR_CCM_AUTH_FAILED;
}
return 0;
}
static int ccm_auth_decrypt(mbedtls_ccm_context *ctx, int mode, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
const unsigned char *tag, size_t tag_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char check_tag[16];
if ((ret = ccm_auth_crypt(ctx, mode, length,
iv, iv_len, add, add_len,
input, output, check_tag, tag_len)) != 0) {
return ret;
}
if ((ret = mbedtls_ccm_compare_tags(tag, check_tag, tag_len)) != 0) {
mbedtls_platform_zeroize(output, length);
return ret;
}
return 0;
}
int mbedtls_ccm_star_auth_decrypt(mbedtls_ccm_context *ctx, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
const unsigned char *tag, size_t tag_len)
{
return ccm_auth_decrypt(ctx, MBEDTLS_CCM_STAR_DECRYPT, length,
iv, iv_len, add, add_len,
input, output, tag, tag_len);
}
int mbedtls_ccm_auth_decrypt(mbedtls_ccm_context *ctx, size_t length,
const unsigned char *iv, size_t iv_len,
const unsigned char *add, size_t add_len,
const unsigned char *input, unsigned char *output,
const unsigned char *tag, size_t tag_len)
{
return ccm_auth_decrypt(ctx, MBEDTLS_CCM_DECRYPT, length,
iv, iv_len, add, add_len,
input, output, tag, tag_len);
}
#endif /* !MBEDTLS_CCM_ALT */
#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
/*
* Examples 1 to 3 from SP800-38C Appendix C
*/
#define NB_TESTS 3
#define CCM_SELFTEST_PT_MAX_LEN 24
#define CCM_SELFTEST_CT_MAX_LEN 32
/*
* The data is the same for all tests, only the used length changes
*/
static const unsigned char key_test_data[] = {
0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f
};
static const unsigned char iv_test_data[] = {
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
0x18, 0x19, 0x1a, 0x1b
};
static const unsigned char ad_test_data[] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13
};
static const unsigned char msg_test_data[CCM_SELFTEST_PT_MAX_LEN] = {
0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
};
static const size_t iv_len_test_data[NB_TESTS] = { 7, 8, 12 };
static const size_t add_len_test_data[NB_TESTS] = { 8, 16, 20 };
static const size_t msg_len_test_data[NB_TESTS] = { 4, 16, 24 };
static const size_t tag_len_test_data[NB_TESTS] = { 4, 6, 8 };
static const unsigned char res_test_data[NB_TESTS][CCM_SELFTEST_CT_MAX_LEN] = {
{ 0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d },
{ 0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62,
0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d,
0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd },
{ 0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a,
0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b,
0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5,
0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 }
};
int mbedtls_ccm_self_test(int verbose)
{
mbedtls_ccm_context ctx;
/*
* Some hardware accelerators require the input and output buffers
* would be in RAM, because the flash is not accessible.
* Use buffers on the stack to hold the test vectors data.
*/
unsigned char plaintext[CCM_SELFTEST_PT_MAX_LEN];
unsigned char ciphertext[CCM_SELFTEST_CT_MAX_LEN];
size_t i;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_ccm_init(&ctx);
if (mbedtls_ccm_setkey(&ctx, MBEDTLS_CIPHER_ID_AES, key_test_data,
8 * sizeof(key_test_data)) != 0) {
if (verbose != 0) {
mbedtls_printf(" CCM: setup failed");
}
return 1;
}
for (i = 0; i < NB_TESTS; i++) {
if (verbose != 0) {
mbedtls_printf(" CCM-AES #%u: ", (unsigned int) i + 1);
}
memset(plaintext, 0, CCM_SELFTEST_PT_MAX_LEN);
memset(ciphertext, 0, CCM_SELFTEST_CT_MAX_LEN);
memcpy(plaintext, msg_test_data, msg_len_test_data[i]);
ret = mbedtls_ccm_encrypt_and_tag(&ctx, msg_len_test_data[i],
iv_test_data, iv_len_test_data[i],
ad_test_data, add_len_test_data[i],
plaintext, ciphertext,
ciphertext + msg_len_test_data[i],
tag_len_test_data[i]);
if (ret != 0 ||
memcmp(ciphertext, res_test_data[i],
msg_len_test_data[i] + tag_len_test_data[i]) != 0) {
if (verbose != 0) {
mbedtls_printf("failed\n");
}
return 1;
}
memset(plaintext, 0, CCM_SELFTEST_PT_MAX_LEN);
ret = mbedtls_ccm_auth_decrypt(&ctx, msg_len_test_data[i],
iv_test_data, iv_len_test_data[i],
ad_test_data, add_len_test_data[i],
ciphertext, plaintext,
ciphertext + msg_len_test_data[i],
tag_len_test_data[i]);
if (ret != 0 ||
memcmp(plaintext, msg_test_data, msg_len_test_data[i]) != 0) {
if (verbose != 0) {
mbedtls_printf("failed\n");
}
return 1;
}
if (verbose != 0) {
mbedtls_printf("passed\n");
}
}
mbedtls_ccm_free(&ctx);
if (verbose != 0) {
mbedtls_printf("\n");
}
return 0;
}
#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
#endif /* MBEDTLS_CCM_C */