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/*
* Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* AES low level APIs are deprecated for public use, but still ok for internal
* use where we're using them to implement the higher level EVP interface, as is
* the case here.
*/
#include "internal/deprecated.h"
#include <openssl/evp.h>
#include <internal/endian.h>
#include <prov/implementations.h>
#include "cipher_aes_gcm_siv.h"
static int aes_gcm_siv_ctr32(PROV_AES_GCM_SIV_CTX *ctx, const unsigned char *init_counter,
unsigned char *out, const unsigned char *in, size_t len);
static int aes_gcm_siv_initkey(void *vctx)
{
PROV_AES_GCM_SIV_CTX *ctx = (PROV_AES_GCM_SIV_CTX *)vctx;
uint8_t output[BLOCK_SIZE];
uint32_t counter = 0x0;
size_t i;
union {
uint32_t counter;
uint8_t block[BLOCK_SIZE];
} data;
int out_len;
EVP_CIPHER *ecb = NULL;
DECLARE_IS_ENDIAN;
switch (ctx->key_len) {
case 16:
ecb = EVP_CIPHER_fetch(ctx->libctx, "AES-128-ECB", NULL);
break;
case 24:
ecb = EVP_CIPHER_fetch(ctx->libctx, "AES-192-ECB", NULL);
break;
case 32:
ecb = EVP_CIPHER_fetch(ctx->libctx, "AES-256-ECB", NULL);
break;
default:
goto err;
}
if (ctx->ecb_ctx == NULL && (ctx->ecb_ctx = EVP_CIPHER_CTX_new()) == NULL)
goto err;
if (!EVP_EncryptInit_ex2(ctx->ecb_ctx, ecb, ctx->key_gen_key, NULL, NULL))
goto err;
memset(&data, 0, sizeof(data));
memcpy(&data.block[sizeof(data.counter)], ctx->nonce, NONCE_SIZE);
/* msg_auth_key is always 16 bytes in size, regardless of AES128/AES256 */
/* counter is stored little-endian */
for (i = 0; i < BLOCK_SIZE; i += 8) {
if (IS_LITTLE_ENDIAN) {
data.counter = counter;
} else {
data.counter = GSWAP4(counter);
}
/* Block size is 16 (128 bits), but only 8 bytes are used */
out_len = BLOCK_SIZE;
if (!EVP_EncryptUpdate(ctx->ecb_ctx, output, &out_len, data.block, BLOCK_SIZE))
goto err;
memcpy(&ctx->msg_auth_key[i], output, 8);
counter++;
}
/* msg_enc_key length is directly tied to key length AES128/AES256 */
for (i = 0; i < ctx->key_len; i += 8) {
if (IS_LITTLE_ENDIAN) {
data.counter = counter;
} else {
data.counter = GSWAP4(counter);
}
/* Block size is 16 bytes (128 bits), but only 8 bytes are used */
out_len = BLOCK_SIZE;
if (!EVP_EncryptUpdate(ctx->ecb_ctx, output, &out_len, data.block, BLOCK_SIZE))
goto err;
memcpy(&ctx->msg_enc_key[i], output, 8);
counter++;
}
if (!EVP_EncryptInit_ex2(ctx->ecb_ctx, ecb, ctx->msg_enc_key, NULL, NULL))
goto err;
/* Freshen up the state */
ctx->used_enc = 0;
ctx->used_dec = 0;
EVP_CIPHER_free(ecb);
return 1;
err:
EVP_CIPHER_CTX_free(ctx->ecb_ctx);
EVP_CIPHER_free(ecb);
ctx->ecb_ctx = NULL;
return 0;
}
static int aes_gcm_siv_aad(PROV_AES_GCM_SIV_CTX *ctx,
const unsigned char *aad, size_t len)
{
size_t to_alloc;
uint8_t *ptr;
uint64_t len64;
/* length of 0 resets the AAD */
if (len == 0) {
OPENSSL_free(ctx->aad);
ctx->aad = NULL;
ctx->aad_len = 0;
return 1;
}
to_alloc = UP16(ctx->aad_len + len);
/* need to check the size of the AAD per RFC8452 */
len64 = to_alloc;
if (len64 > ((uint64_t)1 << 36))
return 0;
ptr = OPENSSL_realloc(ctx->aad, to_alloc);
if (ptr == NULL)
return 0;
ctx->aad = ptr;
memcpy(&ctx->aad[ctx->aad_len], aad, len);
ctx->aad_len += len;
if (to_alloc > ctx->aad_len)
memset(&ctx->aad[ctx->aad_len], 0, to_alloc - ctx->aad_len);
return 1;
}
static int aes_gcm_siv_finish(PROV_AES_GCM_SIV_CTX *ctx)
{
int ret = 0;
if (ctx->enc)
return ctx->generated_tag;
ret = !CRYPTO_memcmp(ctx->tag, ctx->user_tag, sizeof(ctx->tag));
ret &= ctx->have_user_tag;
return ret;
}
static int aes_gcm_siv_encrypt(PROV_AES_GCM_SIV_CTX *ctx, const unsigned char *in,
unsigned char *out, size_t len)
{
uint64_t len_blk[2];
uint8_t S_s[TAG_SIZE];
uint8_t counter_block[TAG_SIZE];
uint8_t padding[BLOCK_SIZE];
size_t i;
int64_t len64 = len;
int out_len;
int error = 0;
DECLARE_IS_ENDIAN;
ctx->generated_tag = 0;
if (!ctx->speed && ctx->used_enc)
return 0;
/* need to check the size of the input! */
if (len64 > ((int64_t)1 << 36) || len == 0)
return 0;
if (IS_LITTLE_ENDIAN) {
len_blk[0] = (uint64_t)ctx->aad_len * 8;
len_blk[1] = (uint64_t)len * 8;
} else {
len_blk[0] = GSWAP8((uint64_t)ctx->aad_len * 8);
len_blk[1] = GSWAP8((uint64_t)len * 8);
}
memset(S_s, 0, TAG_SIZE);
ossl_polyval_ghash_init(ctx->Htable, (const uint64_t*)ctx->msg_auth_key);
if (ctx->aad != NULL) {
/* AAD is allocated with padding, but need to adjust length */
ossl_polyval_ghash_hash(ctx->Htable, S_s, ctx->aad, UP16(ctx->aad_len));
}
if (DOWN16(len) > 0)
ossl_polyval_ghash_hash(ctx->Htable, S_s, (uint8_t *) in, DOWN16(len));
if (!IS16(len)) {
/* deal with padding - probably easier to memset the padding first rather than calculate */
memset(padding, 0, sizeof(padding));
memcpy(padding, &in[DOWN16(len)], REMAINDER16(len));
ossl_polyval_ghash_hash(ctx->Htable, S_s, padding, sizeof(padding));
}
ossl_polyval_ghash_hash(ctx->Htable, S_s, (uint8_t *) len_blk, sizeof(len_blk));
for (i = 0; i < NONCE_SIZE; i++)
S_s[i] ^= ctx->nonce[i];
S_s[TAG_SIZE - 1] &= 0x7f;
out_len = sizeof(ctx->tag);
error |= !EVP_EncryptUpdate(ctx->ecb_ctx
|