/* ====================================================================
* Copyright (c) 2010 The OpenSSL Project. All rights reserved.
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* 3. All advertising materials mentioning features or use of this
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* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
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* 5. Products derived from this software may not be called "OpenSSL"
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#include <openssl_grpc/cmac.h>
#include <assert.h>
#include <string.h>
#include <openssl_grpc/aes.h>
#include <openssl_grpc/cipher.h>
#include <openssl_grpc/mem.h>
#include "../internal.h"
struct cmac_ctx_st {
EVP_CIPHER_CTX cipher_ctx;
// k1 and k2 are the CMAC subkeys. See
// https://tools.ietf.org/html/rfc4493#section-2.3
uint8_t k1[AES_BLOCK_SIZE];
uint8_t k2[AES_BLOCK_SIZE];
// Last (possibly partial) scratch
uint8_t block[AES_BLOCK_SIZE];
// block_used contains the number of valid bytes in |block|.
unsigned block_used;
};
static void CMAC_CTX_init(CMAC_CTX *ctx) {
EVP_CIPHER_CTX_init(&ctx->cipher_ctx);
}
static void CMAC_CTX_cleanup(CMAC_CTX *ctx) {
EVP_CIPHER_CTX_cleanup(&ctx->cipher_ctx);
OPENSSL_cleanse(ctx->k1, sizeof(ctx->k1));
OPENSSL_cleanse(ctx->k2, sizeof(ctx->k2));
OPENSSL_cleanse(ctx->block, sizeof(ctx->block));
}
int AES_CMAC(uint8_t out[16], const uint8_t *key, size_t key_len,
const uint8_t *in, size_t in_len) {
const EVP_CIPHER *cipher;
switch (key_len) {
case 16:
cipher = EVP_aes_128_cbc();
break;
case 32:
cipher = EVP_aes_256_cbc();
break;
default:
return 0;
}
size_t scratch_out_len;
CMAC_CTX ctx;
CMAC_CTX_init(&ctx);
const int ok = CMAC_Init(&ctx, key, key_len, cipher, NULL /* engine */) &&
CMAC_Update(&ctx, in, in_len) &&
CMAC_Final(&ctx, out, &scratch_out_len);
CMAC_CTX_cleanup(&ctx);
return ok;
}
CMAC_CTX *CMAC_CTX_new(void) {
CMAC_CTX *ctx = OPENSSL_malloc(sizeof(*ctx));
if (ctx != NULL) {
CMAC_CTX_init(ctx);
}
return ctx;
}
void CMAC_CTX_free(CMAC_CTX *ctx) {
if (ctx == NULL) {
return;
}
CMAC_CTX_cleanup(ctx);
OPENSSL_free(ctx);
}
int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in) {
if (!EVP_CIPHER_CTX_copy(&out->cipher_ctx, &in->cipher_ctx)) {
return 0;
}
OPENSSL_memcpy(out->k1, in->k1, AES_BLOCK_SIZE);
OPENSSL_memcpy(out->k2, in->k2, AES_BLOCK_SIZE);
OPENSSL_memcpy(out->block, in->block, AES_BLOCK_SIZE);
out->block_used = in->block_used;
return 1;
}
// binary_field_mul_x_128 treats the 128 bits at |in| as an element of GF(2¹²⁸)
// with a hard-coded reduction polynomial and sets |out| as x times the input.
//
// See https://tools.ietf.org/html/rfc4493#section-2.3
static void binary_field_mul_x_128(uint8_t out[16], const uint8_t in[16]) {
unsigned i;
// Shift |in| to left, including carry.
for (i = 0; i < 15; i++) {
out[i] = (in[i] << 1) | (in[i+1] >> 7);
}
// If MSB set fixup with R.
const uint8_t carry = in[0] >> 7;
out[i] = (in[i] << 1) ^ ((0 - carry) & 0x87);
}
// binary_field_mul_x_64 behaves like |binary_field_mul_x_128| but acts on an
// element of GF(2⁶⁴).
//
// See https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-38b.pdf
static void binary_field_mul_x_64(uint8_t out[8], const uint8_t in[8]) {
unsigned i;
// Shift |in| to left, including carry.
for (i = 0; i < 7; i++) {
out[i] = (in[i] << 1) | (in[i+1] >> 7);
}
// If MSB set fixup with R.
const uint8_t carry = in[0] >> 7;
out[i] = (in[i] << 1) ^ ((0 - carry) & 0x1b);
}
static const uint8_t kZeroIV[AES_BLOCK_SIZE] = {0};
int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t key_len,
const EVP_CIPHER *cipher, ENGINE *engine) {
uint8_t scratch[AES_BLOCK_SIZE];
size_t block_size = EVP_CIPHER_block_size(cipher);
if ((block_size != AES_BLOCK_SIZE && block_size != 8 /* 3-DES */) ||
EVP_CIPHER_key_length(cipher) != key_len ||
!EVP_EncryptInit_ex(&ctx->cipher_ctx, cipher, NULL, key, kZeroIV) ||
!EVP_Cipher(&ctx->cipher_ctx, scratch, kZeroIV, block_size) ||
// Reset context again ready for first data.
!EVP_EncryptInit_ex(&ctx->cipher_ctx, NULL, NULL, NULL, kZeroIV)) {
return 0;
}
if (block_size == AES_BLOCK_SIZE) {
binary_field_mul_x_128(ctx->k1, scratch);
binary_field_mul_x_128(ctx->k2, ctx->k1);
} else {
binary_field_mul_x_64(ctx->k1, scratch);
binary_field_mul_x_64(ctx->k2, ctx->k1);
}
ctx->block_used = 0;
return 1;
}
int CMAC_Reset(CMAC_CTX *ctx) {
ctx->block_used = 0;
return EVP_EncryptInit_ex(&ctx->cipher_ctx, NULL, NULL, NULL, kZeroIV);
}
int CMAC_Update(CMAC_CTX *ctx, const uint8_t *in, size_t in_len) {
size_t block_size = EVP_CIPHER_CTX_block_size(&ctx->cipher_ctx);
assert(block_size <= AES_BLOCK_SIZE);
uint8_t scratch[AES_BLOCK_SIZE];
if (ctx->block_used > 0) {
size_t todo = block_size - ctx->block_used;
if (in_len < todo) {
todo = in_len;
}
OPENSSL_memcpy(ctx->block + ctx->block_used, in, todo);
in += todo;
in_len -= todo;
ctx->block_used += todo;
// If |in_len| is zero then either |ctx->block_used| is less than
// |block_size|, in which case we can stop here, or |ctx->block_used| is
// exactly |block_size| but there's no more data to process. In the latter
// case we don't want to process this block now because it might be the last
// block and that block is treated specially.
if (in_len == 0) {
return 1;
}
assert(ctx->block_used == block_size);
if (!EVP_Cipher(&ctx->cipher_ctx, scratch, ctx->block, block_size)) {
return 0;
}
}
// Encrypt all but one of the remaining blocks.
while (in_len > block_size) {
if (!EVP_Cipher(&ctx->cipher_ctx, scratch, in, block_size)) {
return 0;
}
in += block_size;
in_len -= block_size;
}
OPENSSL_memcpy(ctx->block, in, in_len);
ctx->block_used = in_len;
return 1;
}
int CMAC_Final(CMAC_CTX *ctx, uint8_t *out, size_t *out_len) {
size_t block_size = EVP_CIPHER_CTX_block_size(&ctx->cipher_ctx);
assert(block_size <= AES_BLOCK_SIZE);
*out_len = block_size;
if (out == NULL) {
return 1;
}
const uint8_t *mask = ctx->k1;
if (ctx->block_used != block_size) {
// If the last block is incomplete, terminate it with a single 'one' bit
// followed by zeros.
ctx->block[ctx->block_used] = 0x80;
OPENSSL_memset(ctx->block + ctx->block_used + 1, 0,
block_size - (ctx->block_used + 1));
mask = ctx->k2;
}
for (unsigned i = 0; i < block_size; i++) {
out[i] = ctx->block[i] ^ mask[i];
}
return EVP_Cipher(&ctx->cipher_ctx, out, out, block_size);
}