ref: 2cdc6577ef8a251bf1740439cf5bfc47050dab41
dir: /third_party/boringssl/src/crypto/fipsmodule/aes/key_wrap.c/
/* ====================================================================
* Copyright (c) 2001-2011 The OpenSSL Project. All rights reserved.
*
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* distribution.
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* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* 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/aes.h>
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <openssl/mem.h>
#include "../../internal.h"
// kDefaultIV is the default IV value given in RFC 3394, 2.2.3.1.
static const uint8_t kDefaultIV[] = {
0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6, 0xa6,
};
static const unsigned kBound = 6;
int AES_wrap_key(const AES_KEY *key, const uint8_t *iv, uint8_t *out,
const uint8_t *in, size_t in_len) {
// See RFC 3394, section 2.2.1. Additionally, note that section 2 requires the
// plaintext be at least two 8-byte blocks.
if (in_len > INT_MAX - 8 || in_len < 16 || in_len % 8 != 0) {
return -1;
}
if (iv == NULL) {
iv = kDefaultIV;
}
OPENSSL_memmove(out + 8, in, in_len);
uint8_t A[AES_BLOCK_SIZE];
OPENSSL_memcpy(A, iv, 8);
size_t n = in_len / 8;
for (unsigned j = 0; j < kBound; j++) {
for (size_t i = 1; i <= n; i++) {
OPENSSL_memcpy(A + 8, out + 8 * i, 8);
AES_encrypt(A, A, key);
uint32_t t = (uint32_t)(n * j + i);
A[7] ^= t & 0xff;
A[6] ^= (t >> 8) & 0xff;
A[5] ^= (t >> 16) & 0xff;
A[4] ^= (t >> 24) & 0xff;
OPENSSL_memcpy(out + 8 * i, A + 8, 8);
}
}
OPENSSL_memcpy(out, A, 8);
return (int)in_len + 8;
}
// aes_unwrap_key_inner performs steps one and two from
// https://tools.ietf.org/html/rfc3394#section-2.2.2
static int aes_unwrap_key_inner(const AES_KEY *key, uint8_t *out,
uint8_t out_iv[8], const uint8_t *in,
size_t in_len) {
// See RFC 3394, section 2.2.2. Additionally, note that section 2 requires the
// plaintext be at least two 8-byte blocks, so the ciphertext must be at least
// three blocks.
if (in_len > INT_MAX || in_len < 24 || in_len % 8 != 0) {
return 0;
}
uint8_t A[AES_BLOCK_SIZE];
OPENSSL_memcpy(A, in, 8);
OPENSSL_memmove(out, in + 8, in_len - 8);
size_t n = (in_len / 8) - 1;
for (unsigned j = kBound - 1; j < kBound; j--) {
for (size_t i = n; i > 0; i--) {
uint32_t t = (uint32_t)(n * j + i);
A[7] ^= t & 0xff;
A[6] ^= (t >> 8) & 0xff;
A[5] ^= (t >> 16) & 0xff;
A[4] ^= (t >> 24) & 0xff;
OPENSSL_memcpy(A + 8, out + 8 * (i - 1), 8);
AES_decrypt(A, A, key);
OPENSSL_memcpy(out + 8 * (i - 1), A + 8, 8);
}
}
memcpy(out_iv, A, 8);
return 1;
}
int AES_unwrap_key(const AES_KEY *key, const uint8_t *iv, uint8_t *out,
const uint8_t *in, size_t in_len) {
uint8_t calculated_iv[8];
if (!aes_unwrap_key_inner(key, out, calculated_iv, in, in_len)) {
return -1;
}
if (iv == NULL) {
iv = kDefaultIV;
}
if (CRYPTO_memcmp(calculated_iv, iv, 8) != 0) {
return -1;
}
return (int)in_len - 8;
}
// kPaddingConstant is used in Key Wrap with Padding. See
// https://tools.ietf.org/html/rfc5649#section-3
static const uint8_t kPaddingConstant[4] = {0xa6, 0x59, 0x59, 0xa6};
int AES_wrap_key_padded(const AES_KEY *key, uint8_t *out, size_t *out_len,
size_t max_out, const uint8_t *in, size_t in_len) {
// See https://tools.ietf.org/html/rfc5649#section-4.1
const uint32_t in_len32_be = CRYPTO_bswap4(in_len);
const uint64_t in_len64 = in_len;
const size_t padded_len = (in_len + 7) & ~7;
*out_len = 0;
if (in_len == 0 || in_len64 > 0xffffffffu || in_len + 7 < in_len ||
padded_len + 8 < padded_len || max_out < padded_len + 8) {
return 0;
}
uint8_t block[AES_BLOCK_SIZE];
memcpy(block, kPaddingConstant, sizeof(kPaddingConstant));
memcpy(block + 4, &in_len32_be, sizeof(in_len32_be));
if (in_len <= 8) {
memset(block + 8, 0, 8);
memcpy(block + 8, in, in_len);
AES_encrypt(block, out, key);
*out_len = AES_BLOCK_SIZE;
return 1;
}
uint8_t *padded_in = OPENSSL_malloc(padded_len);
if (padded_in == NULL) {
return 0;
}
assert(padded_len >= 8);
memset(padded_in + padded_len - 8, 0, 8);
memcpy(padded_in, in, in_len);
const int ret = AES_wrap_key(key, block, out, padded_in, padded_len);
OPENSSL_free(padded_in);
if (ret < 0) {
return 0;
}
*out_len = ret;
return 1;
}
int AES_unwrap_key_padded(const AES_KEY *key, uint8_t *out, size_t *out_len,
size_t max_out, const uint8_t *in, size_t in_len) {
*out_len = 0;
if (in_len < AES_BLOCK_SIZE || max_out < in_len - 8) {
return 0;
}
uint8_t iv[8];
if (in_len == AES_BLOCK_SIZE) {
uint8_t block[AES_BLOCK_SIZE];
AES_decrypt(in, block, key);
memcpy(iv, block, sizeof(iv));
memcpy(out, block + 8, 8);
} else if (!aes_unwrap_key_inner(key, out, iv, in, in_len)) {
return 0;
}
assert(in_len % 8 == 0);
crypto_word_t ok = constant_time_eq_int(
CRYPTO_memcmp(iv, kPaddingConstant, sizeof(kPaddingConstant)), 0);
uint32_t claimed_len32;
memcpy(&claimed_len32, iv + 4, sizeof(claimed_len32));
const size_t claimed_len = CRYPTO_bswap4(claimed_len32);
ok &= ~constant_time_is_zero_w(claimed_len);
ok &= constant_time_eq_w((claimed_len - 1) >> 3, (in_len - 9) >> 3);
// Check that padding bytes are all zero.
for (size_t i = in_len - 15; i < in_len - 8; i++) {
ok &= constant_time_is_zero_w(constant_time_ge_8(i, claimed_len) & out[i]);
}
*out_len = constant_time_select_w(ok, claimed_len, 0);
return ok & 1;
}