blob: 1b5410918fe55181df1934c581077635568eee0a [file] [log] [blame]
/* Copyright (c) 2014, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <openssl/aead.h>
#include <openssl/cipher.h>
#include <openssl/err.h>
#include <openssl/hmac.h>
#include <openssl/md5.h>
#include <openssl/mem.h>
#include <openssl/sha.h>
#include "internal.h"
typedef struct {
EVP_CIPHER_CTX cipher_ctx;
EVP_MD_CTX md_ctx;
/* enc_key is the portion of the key used for the stream or block cipher. It
* is retained separately to allow the EVP_CIPHER_CTX to be initialized once
* the direction is known. */
uint8_t enc_key[EVP_MAX_KEY_LENGTH];
uint8_t enc_key_len;
/* iv is the portion of the key used for the fixed IV. It is retained
* separately to allow the EVP_CIPHER_CTX to be initialized once the direction
* is known. */
uint8_t iv[EVP_MAX_IV_LENGTH];
uint8_t iv_len;
char initialized;
} AEAD_SSL3_CTX;
static int ssl3_mac(AEAD_SSL3_CTX *ssl3_ctx, uint8_t *out, unsigned *out_len,
const uint8_t *ad, size_t ad_len, const uint8_t *in,
size_t in_len) {
size_t md_size = EVP_MD_CTX_size(&ssl3_ctx->md_ctx);
size_t pad_len = (md_size == 20) ? 40 : 48;
/* To allow for CBC mode which changes cipher length, |ad| doesn't include the
* length for legacy ciphers. */
uint8_t ad_extra[2];
ad_extra[0] = (uint8_t)(in_len >> 8);
ad_extra[1] = (uint8_t)(in_len & 0xff);
EVP_MD_CTX md_ctx;
EVP_MD_CTX_init(&md_ctx);
uint8_t pad[EVP_MAX_MD_SIZE];
uint8_t tmp[EVP_MAX_MD_SIZE];
memset(pad, 0x36, pad_len);
if (!EVP_MD_CTX_copy_ex(&md_ctx, &ssl3_ctx->md_ctx) ||
!EVP_DigestUpdate(&md_ctx, pad, pad_len) ||
!EVP_DigestUpdate(&md_ctx, ad, ad_len) ||
!EVP_DigestUpdate(&md_ctx, ad_extra, sizeof(ad_extra)) ||
!EVP_DigestUpdate(&md_ctx, in, in_len) ||
!EVP_DigestFinal_ex(&md_ctx, tmp, NULL)) {
EVP_MD_CTX_cleanup(&md_ctx);
return 0;
}
memset(pad, 0x5c, pad_len);
if (!EVP_MD_CTX_copy_ex(&md_ctx, &ssl3_ctx->md_ctx) ||
!EVP_DigestUpdate(&md_ctx, pad, pad_len) ||
!EVP_DigestUpdate(&md_ctx, tmp, md_size) ||
!EVP_DigestFinal_ex(&md_ctx, out, out_len)) {
EVP_MD_CTX_cleanup(&md_ctx);
return 0;
}
EVP_MD_CTX_cleanup(&md_ctx);
return 1;
}
static void aead_ssl3_cleanup(EVP_AEAD_CTX *ctx) {
AEAD_SSL3_CTX *ssl3_ctx = (AEAD_SSL3_CTX *)ctx->aead_state;
EVP_CIPHER_CTX_cleanup(&ssl3_ctx->cipher_ctx);
EVP_MD_CTX_cleanup(&ssl3_ctx->md_ctx);
OPENSSL_cleanse(&ssl3_ctx->enc_key, sizeof(ssl3_ctx->enc_key));
OPENSSL_cleanse(&ssl3_ctx->iv, sizeof(ssl3_ctx->iv));
OPENSSL_free(ssl3_ctx);
ctx->aead_state = NULL;
}
static int aead_ssl3_init(EVP_AEAD_CTX *ctx, const uint8_t *key, size_t key_len,
size_t tag_len, const EVP_CIPHER *cipher,
const EVP_MD *md) {
if (tag_len != EVP_AEAD_DEFAULT_TAG_LENGTH &&
tag_len != EVP_MD_size(md)) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_init, CIPHER_R_UNSUPPORTED_TAG_SIZE);
return 0;
}
if (key_len != EVP_AEAD_key_length(ctx->aead)) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_init, CIPHER_R_BAD_KEY_LENGTH);
return 0;
}
size_t mac_key_len = EVP_MD_size(md);
size_t enc_key_len = EVP_CIPHER_key_length(cipher);
size_t iv_len = EVP_CIPHER_iv_length(cipher);
assert(mac_key_len + enc_key_len + iv_len == key_len);
assert(mac_key_len < 256);
assert(enc_key_len < 256);
assert(iv_len < 256);
/* Although EVP_rc4() is a variable-length cipher, the default key size is
* correct for SSL3. */
AEAD_SSL3_CTX *ssl3_ctx = OPENSSL_malloc(sizeof(AEAD_SSL3_CTX));
if (ssl3_ctx == NULL) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_init, ERR_R_MALLOC_FAILURE);
return 0;
}
EVP_CIPHER_CTX_init(&ssl3_ctx->cipher_ctx);
EVP_MD_CTX_init(&ssl3_ctx->md_ctx);
memcpy(ssl3_ctx->enc_key, &key[mac_key_len], enc_key_len);
ssl3_ctx->enc_key_len = (uint8_t)enc_key_len;
memcpy(ssl3_ctx->iv, &key[mac_key_len + enc_key_len], iv_len);
ssl3_ctx->iv_len = (uint8_t)iv_len;
ssl3_ctx->initialized = 0;
ctx->aead_state = ssl3_ctx;
if (!EVP_CipherInit_ex(&ssl3_ctx->cipher_ctx, cipher, NULL, NULL, NULL, 0) ||
!EVP_DigestInit_ex(&ssl3_ctx->md_ctx, md, NULL) ||
!EVP_DigestUpdate(&ssl3_ctx->md_ctx, key, mac_key_len)) {
aead_ssl3_cleanup(ctx);
return 0;
}
EVP_CIPHER_CTX_set_padding(&ssl3_ctx->cipher_ctx, 0);
return 1;
}
/* aead_ssl3_ensure_cipher_init initializes |ssl3_ctx| for encryption (or
* decryption, if |encrypt| is zero). If it has already been initialized, it
* ensures the direction matches and fails otherwise. It returns one on success
* and zero on failure.
*
* Note that, unlike normal AEADs, legacy SSL3 AEADs may not be used concurrently
* due to this (and bulk-cipher-internal) statefulness. */
static int aead_ssl3_ensure_cipher_init(AEAD_SSL3_CTX *ssl3_ctx, int encrypt) {
if (!ssl3_ctx->initialized) {
/* Finish initializing the EVP_CIPHER_CTX now that the direction is
* known. */
if (!EVP_CipherInit_ex(&ssl3_ctx->cipher_ctx, NULL, NULL, ssl3_ctx->enc_key,
ssl3_ctx->iv, encrypt)) {
return 0;
}
ssl3_ctx->initialized = 1;
} else if (ssl3_ctx->cipher_ctx.encrypt != encrypt) {
/* Unlike a normal AEAD, using an SSL3 AEAD once freezes the direction. */
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_ensure_cipher_init,
CIPHER_R_INVALID_OPERATION);
return 0;
}
return 1;
}
static int aead_ssl3_seal(const EVP_AEAD_CTX *ctx, uint8_t *out,
size_t *out_len, size_t max_out_len,
const uint8_t *nonce, size_t nonce_len,
const uint8_t *in, size_t in_len,
const uint8_t *ad, size_t ad_len) {
AEAD_SSL3_CTX *ssl3_ctx = (AEAD_SSL3_CTX *)ctx->aead_state;
size_t total = 0;
if (in_len + EVP_AEAD_max_overhead(ctx->aead) < in_len ||
in_len > INT_MAX) {
/* EVP_CIPHER takes int as input. */
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_seal, CIPHER_R_TOO_LARGE);
return 0;
}
if (max_out_len < in_len + EVP_AEAD_max_overhead(ctx->aead)) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_seal, CIPHER_R_BUFFER_TOO_SMALL);
return 0;
}
if (nonce_len != 0) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_seal, CIPHER_R_IV_TOO_LARGE);
return 0;
}
if (ad_len != 11 - 2) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_seal, CIPHER_R_INVALID_AD_SIZE);
return 0;
}
if (!aead_ssl3_ensure_cipher_init(ssl3_ctx, 1)) {
return 0;
}
/* Compute the MAC. This must be first in case the operation is being done
* in-place. */
uint8_t mac[EVP_MAX_MD_SIZE];
unsigned mac_len;
if (!ssl3_mac(ssl3_ctx, mac, &mac_len, ad, ad_len, in, in_len)) {
return 0;
}
/* Encrypt the input. */
int len;
if (!EVP_EncryptUpdate(&ssl3_ctx->cipher_ctx, out, &len, in,
(int)in_len)) {
return 0;
}
total = len;
/* Feed the MAC into the cipher. */
if (!EVP_EncryptUpdate(&ssl3_ctx->cipher_ctx, out + total, &len, mac,
(int)mac_len)) {
return 0;
}
total += len;
unsigned block_size = EVP_CIPHER_CTX_block_size(&ssl3_ctx->cipher_ctx);
if (block_size > 1) {
assert(block_size <= 256);
assert(EVP_CIPHER_CTX_mode(&ssl3_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE);
/* Compute padding and feed that into the cipher. */
uint8_t padding[256];
unsigned padding_len = block_size - ((in_len + mac_len) % block_size);
memset(padding, 0, padding_len - 1);
padding[padding_len - 1] = padding_len - 1;
if (!EVP_EncryptUpdate(&ssl3_ctx->cipher_ctx, out + total, &len, padding,
(int)padding_len)) {
return 0;
}
total += len;
}
if (!EVP_EncryptFinal_ex(&ssl3_ctx->cipher_ctx, out + total, &len)) {
return 0;
}
total += len;
*out_len = total;
return 1;
}
static int aead_ssl3_open(const EVP_AEAD_CTX *ctx, uint8_t *out,
size_t *out_len, size_t max_out_len,
const uint8_t *nonce, size_t nonce_len,
const uint8_t *in, size_t in_len,
const uint8_t *ad, size_t ad_len) {
AEAD_SSL3_CTX *ssl3_ctx = (AEAD_SSL3_CTX *)ctx->aead_state;
size_t mac_len = EVP_MD_CTX_size(&ssl3_ctx->md_ctx);
if (in_len < mac_len) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_open, CIPHER_R_BAD_DECRYPT);
return 0;
}
if (max_out_len < in_len) {
/* This requires that the caller provide space for the MAC, even though it
* will always be removed on return. */
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_open, CIPHER_R_BUFFER_TOO_SMALL);
return 0;
}
if (nonce_len != 0) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_open, CIPHER_R_TOO_LARGE);
return 0;
}
if (ad_len != 11 - 2) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_open, CIPHER_R_INVALID_AD_SIZE);
return 0;
}
if (in_len > INT_MAX) {
/* EVP_CIPHER takes int as input. */
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_open, CIPHER_R_TOO_LARGE);
return 0;
}
if (!aead_ssl3_ensure_cipher_init(ssl3_ctx, 0)) {
return 0;
}
/* Decrypt to get the plaintext + MAC + padding. */
size_t total = 0;
int len;
if (!EVP_DecryptUpdate(&ssl3_ctx->cipher_ctx, out, &len, in, (int)in_len)) {
return 0;
}
total += len;
if (!EVP_DecryptFinal_ex(&ssl3_ctx->cipher_ctx, out + total, &len)) {
return 0;
}
total += len;
assert(total == in_len);
/* Remove CBC padding and MAC. This would normally be timing-sensitive, but SSLv3 CBC
* ciphers are already broken. Support will be removed eventually.
* https://www.openssl.org/~bodo/ssl-poodle.pdf */
unsigned data_len;
if (EVP_CIPHER_CTX_mode(&ssl3_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE) {
unsigned padding_length = out[total - 1];
if (total < padding_length + 1 + mac_len) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_open, CIPHER_R_BAD_DECRYPT);
return 0;
}
/* The padding must be minimal. */
if (padding_length + 1 > EVP_CIPHER_CTX_block_size(&ssl3_ctx->cipher_ctx)) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_open, CIPHER_R_BAD_DECRYPT);
return 0;
}
data_len = total - padding_length - 1 - mac_len;
} else {
data_len = total - mac_len;
}
/* Compute the MAC and compare against the one in the record. */
uint8_t mac[EVP_MAX_MD_SIZE];
if (!ssl3_mac(ssl3_ctx, mac, NULL, ad, ad_len, out, data_len)) {
return 0;
}
if (CRYPTO_memcmp(&out[data_len], mac, mac_len) != 0) {
OPENSSL_PUT_ERROR(CIPHER, aead_ssl3_open, CIPHER_R_BAD_DECRYPT);
return 0;
}
*out_len = data_len;
return 1;
}
static int aead_rc4_md5_ssl3_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
size_t key_len, size_t tag_len) {
return aead_ssl3_init(ctx, key, key_len, tag_len, EVP_rc4(), EVP_md5());
}
static int aead_rc4_sha1_ssl3_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
size_t key_len, size_t tag_len) {
return aead_ssl3_init(ctx, key, key_len, tag_len, EVP_rc4(), EVP_sha1());
}
static int aead_aes_128_cbc_sha1_ssl3_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
size_t key_len, size_t tag_len) {
return aead_ssl3_init(ctx, key, key_len, tag_len, EVP_aes_128_cbc(),
EVP_sha1());
}
static int aead_aes_256_cbc_sha1_ssl3_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
size_t key_len, size_t tag_len) {
return aead_ssl3_init(ctx, key, key_len, tag_len, EVP_aes_256_cbc(),
EVP_sha1());
}
static int aead_des_ede3_cbc_sha1_ssl3_init(EVP_AEAD_CTX *ctx,
const uint8_t *key, size_t key_len,
size_t tag_len) {
return aead_ssl3_init(ctx, key, key_len, tag_len, EVP_des_ede3_cbc(),
EVP_sha1());
}
static const EVP_AEAD aead_rc4_md5_ssl3 = {
MD5_DIGEST_LENGTH + 16, /* key len (MD5 + RC4) */
0, /* nonce len */
MD5_DIGEST_LENGTH, /* overhead */
MD5_DIGEST_LENGTH, /* max tag length */
aead_rc4_md5_ssl3_init,
aead_ssl3_cleanup,
aead_ssl3_seal,
aead_ssl3_open,
};
static const EVP_AEAD aead_rc4_sha1_ssl3 = {
SHA_DIGEST_LENGTH + 16, /* key len (SHA1 + RC4) */
0, /* nonce len */
SHA_DIGEST_LENGTH, /* overhead */
SHA_DIGEST_LENGTH, /* max tag length */
aead_rc4_sha1_ssl3_init,
aead_ssl3_cleanup,
aead_ssl3_seal,
aead_ssl3_open,
};
static const EVP_AEAD aead_aes_128_cbc_sha1_ssl3 = {
SHA_DIGEST_LENGTH + 16 + 16, /* key len (SHA1 + AES128 + IV) */
0, /* nonce len */
16 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
SHA_DIGEST_LENGTH, /* max tag length */
aead_aes_128_cbc_sha1_ssl3_init,
aead_ssl3_cleanup,
aead_ssl3_seal,
aead_ssl3_open,
};
static const EVP_AEAD aead_aes_256_cbc_sha1_ssl3 = {
SHA_DIGEST_LENGTH + 32 + 16, /* key len (SHA1 + AES256 + IV) */
0, /* nonce len */
16 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
SHA_DIGEST_LENGTH, /* max tag length */
aead_aes_256_cbc_sha1_ssl3_init,
aead_ssl3_cleanup,
aead_ssl3_seal,
aead_ssl3_open,
};
static const EVP_AEAD aead_des_ede3_cbc_sha1_ssl3 = {
SHA_DIGEST_LENGTH + 24 + 8, /* key len (SHA1 + 3DES + IV) */
0, /* nonce len */
8 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
SHA_DIGEST_LENGTH, /* max tag length */
aead_des_ede3_cbc_sha1_ssl3_init,
aead_ssl3_cleanup,
aead_ssl3_seal,
aead_ssl3_open,
};
const EVP_AEAD *EVP_aead_rc4_md5_ssl3(void) { return &aead_rc4_md5_ssl3; }
const EVP_AEAD *EVP_aead_rc4_sha1_ssl3(void) { return &aead_rc4_sha1_ssl3; }
const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_ssl3(void) {
return &aead_aes_128_cbc_sha1_ssl3;
}
const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_ssl3(void) {
return &aead_aes_256_cbc_sha1_ssl3;
}
const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_ssl3(void) {
return &aead_des_ede3_cbc_sha1_ssl3;
}