/*
* AES-based functions
*
* - AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
* - One-Key CBC MAC (OMAC1, i.e., CMAC) hash with AES-128
* - AES-128 CTR mode encryption
* - AES-128 EAX mode encryption/decryption
* - AES-128 CBC
*
* Copyright (c) 2003-2007, Jouni Malinen <j@w1.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Alternatively, this software may be distributed under the terms of BSD
* license.
*
* See README and COPYING for more details.
*/
#include "includes.h"
#include "common.h"
#include "aes_wrap.h"
#include "crypto.h"
#ifndef CONFIG_NO_AES_WRAP
/**
* aes_wrap - Wrap keys with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
* @kek: 16-octet Key encryption key (KEK)
* @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
* bytes
* @plain: Plaintext key to be wrapped, n * 64 bits
* @cipher: Wrapped key, (n + 1) * 64 bits
* Returns: 0 on success, -1 on failure
*/
int aes_wrap(const u8 *kek, int n, const u8 *plain, u8 *cipher)
{
u8 *a, *r, b[16];
int i, j;
void *ctx;
a = cipher;
r = cipher + 8;
/* 1) Initialize variables. */
os_memset(a, 0xa6, 8);
os_memcpy(r, plain, 8 * n);
ctx = aes_encrypt_init(kek, 16);
if (ctx == NULL)
return -1;
/* 2) Calculate intermediate values.
* For j = 0 to 5
* For i=1 to n
* B = AES(K, A | R[i])
* A = MSB(64, B) ^ t where t = (n*j)+i
* R[i] = LSB(64, B)
*/
for (j = 0; j <= 5; j++) {
r = cipher + 8;
for (i = 1; i <= n; i++) {
os_memcpy(b, a, 8);
os_memcpy(b + 8, r, 8);
aes_encrypt(ctx, b, b);
os_memcpy(a, b, 8);
a[7] ^= n * j + i;
os_memcpy(r, b + 8, 8);
r += 8;
}
}
aes_encrypt_deinit(ctx);
/* 3) Output the results.
*
* These are already in @cipher due to the location of temporary
* variables.
*/
return 0;
}
#endif /* CONFIG_NO_AES_WRAP */
#ifndef CONFIG_NO_AES_UNWRAP
/**
* aes_unwrap - Unwrap key with AES Key Wrap Algorithm (128-bit KEK) (RFC3394)
* @kek: Key encryption key (KEK)
* @n: Length of the plaintext key in 64-bit units; e.g., 2 = 128-bit = 16
* bytes
* @cipher: Wrapped key to be unwrapped, (n + 1) * 64 bits
* @plain: Plaintext key, n * 64 bits
* Returns: 0 on success, -1 on failure (e.g., integrity verification failed)
*/
int aes_unwrap(const u8 *kek, int n, const u8 *cipher, u8 *plain)
{
u8 a[8], *r, b[16];
int i, j;
void *ctx;
/* 1) Initialize variables. */
os_memcpy(a, cipher, 8);
r = plain;
os_memcpy(r, cipher + 8, 8 * n);
ctx = aes_decrypt_init(kek, 16);
if (ctx == NULL)
return -1;
/* 2) Compute intermediate values.
* For j = 5 to 0
* For i = n to 1
* B = AES-1(K, (A ^ t) | R[i]) where t = n*j+i
* A = MSB(64, B)
* R[i] = LSB(64, B)
*/
for (j = 5; j >= 0; j--) {
r = plain + (n - 1) * 8;
for (i = n; i >= 1; i--) {
os_memcpy(b, a, 8);
b[7] ^= n * j + i;
os_memcpy(b + 8, r, 8);
aes_decrypt(ctx, b, b);
os_memcpy(a, b, 8);
os_memcpy(r, b + 8, 8);
r -= 8;
}
}
aes_decrypt_deinit(ctx);
/* 3) Output results.
*
* These are already in @plain due to the location of temporary
* variables. Just verify that the IV matches with the expected value.
*/
for (i = 0; i < 8; i++) {
if (a[i] != 0xa6)
return -1;
}
return 0;
}
#endif /* CONFIG_NO_AES_UNWRAP */
#define BLOCK_SIZE 16
#ifndef CONFIG_NO_AES_OMAC1
static void gf_mulx(u8 *pad)
{
int i, carry;
carry = pad[0] & 0x80;
for (i = 0; i < BLOCK_SIZE - 1; i++)
pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
pad[BLOCK_SIZE - 1] <<= 1;
if (carry)
pad[BLOCK_SIZE - 1] ^= 0x87;
}
/**
* omac1_aes_128_vector - One-Key CBC MAC (OMAC1) hash with AES-128
* @key: 128-bit key for the hash operation
* @num_elem: Number of elements in the data vector
* @addr: Pointers to the data areas
* @len: Lengths of the data blocks
* @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
* Returns: 0 on success, -1 on failure
*
* This is a mode for using block cipher (AES in this case) for authentication.
* OMAC1 was standardized with the name CMAC by NIST in a Special Publication
* (SP) 800-38B.
*/
int omac1_aes_128_vector(const u8 *key, size_t num_elem,
const u8 *addr[], const size_t *len, u8 *mac)
{
void *ctx;
u8 cbc[BLOCK_SIZE], pad[BLOCK_SIZE];
const u8 *pos, *end;
size_t i, e, left, total_len;
ctx = aes_encrypt_init(key, 16);
if (ctx == NULL)
return -1;
os_memset(cbc, 0, BLOCK_SIZE);
total_len = 0;
for (e = 0; e < num_elem; e++)
total_len += len[e];
left = total_len;
e = 0;
pos = addr[0];
end = pos + len[0];
while (left >= BLOCK_SIZE) {
for (i = 0; i < BLOCK_SIZE; i++) {
cbc[i] ^= *pos++;
if (pos >= end) {
e++;
pos = addr[e];
end = pos + len[e];
}
}
if (left > BLOCK_SIZE)
aes_encrypt(ctx, cbc, cbc);
left -= BLOCK_SIZE;
}
os_memset(pad, 0, BLOCK_SIZE);
aes_encrypt(ctx, pad, pad);
gf_mulx(pad);
if (left || total_len == 0) {
for (i = 0; i < left; i++) {
cbc[i] ^= *pos++;
if (pos >= end) {
e++;
pos = addr[e];
end = pos + len[e];
}
}
cbc[left] ^= 0x80;
gf_mulx(pad);
}
for (i = 0; i < BLOCK_SIZE; i++)
pad[i] ^= cbc[i];
aes_encrypt(ctx, pad, mac);
aes_encrypt_deinit(ctx);
return 0;
}
/**
* omac1_aes_128 - One-Key CBC MAC (OMAC1) hash with AES-128 (aka AES-CMAC)
* @key: 128-bit key for the hash operation
* @data: Data buffer for which a MAC is determined
* @data_len: Length of data buffer in bytes
* @mac: Buffer for MAC (128 bits, i.e., 16 bytes)
* Returns: 0 on success, -1 on failure
*
* This is a mode for using block cipher (AES in this case) for authentication.
* OMAC1 was standardized with the name CMAC by NIST in a Special Publication
* (SP) 800-38B.
*/
int omac1_aes_128(const u8 *key, const u8 *data, size_t data_len, u8 *mac)
{
return omac1_aes_128_vector(key, 1, &data, &data_len, mac);
}
#endif /* CONFIG_NO_AES_OMAC1 */
#ifndef CONFIG_NO_AES_ENCRYPT_BLOCK
/**
* aes_128_encrypt_block - Perform one AES 128-bit block operation
* @key: Key for AES
* @in: Input data (16 bytes)
* @out: Output of the AES block operation (16 bytes)
* Returns: 0 on success, -1 on failure
*/
int aes_128_encrypt_block(const u8 *key, const u8 *in, u8 *out)
{
void *ctx;
ctx = aes_encrypt_init(key, 16);
if (ctx == NULL)
return -1;
aes_encrypt(ctx, in, out);
aes_encrypt_deinit(ctx);
return 0;
}
#endif /* CONFIG_NO_AES_ENCRYPT_BLOCK */
#ifndef CONFIG_NO_AES_CTR
/**
* aes_128_ctr_encrypt - AES-128 CTR mode encryption
* @key: Key for encryption (16 bytes)
* @nonce: Nonce for counter mode (16 bytes)
* @data: Data to encrypt in-place
* @data_len: Length of data in bytes
* Returns: 0 on success, -1 on failure
*/
int aes_128_ctr_encrypt(const u8 *key, const u8 *nonce,
u8 *data, size_t data_len)
{
void *ctx;
size_t j, len, left = data_len;
int i;
u8 *pos = data;
u8 counter[BLOCK_SIZE], buf[BLOCK_SIZE];
ctx = aes_encrypt_init(key, 16);
if (ctx == NULL)
return -1;
os_memcpy(counter, nonce, BLOCK_SIZE);
while (left > 0) {
aes_encrypt(ctx, counter, buf);
len = (left < BLOCK_SIZE) ? left : BLOCK_SIZE;
for (j = 0; j < len; j++)
pos[j] ^= buf[j];
pos += len;
left -= len;
for (i = BLOCK_SIZE - 1; i >= 0; i--) {
counter[i]++;
if (counter[i])
break;
}
}
aes_encrypt_deinit(ctx);
return 0;
}
#endif /* CONFIG_NO_AES_CTR */
#ifndef CONFIG_NO_AES_EAX
/**
* aes_128_eax_encrypt - AES-128 EAX mode encryption
* @key: Key for encryption (16 bytes)
* @nonce: Nonce for counter mode
* @nonce_len: Nonce length in bytes
* @hdr: Header data to be authenticity protected
* @hdr_len: Length of the header data bytes
* @data: Data to encrypt in-place
* @data_len: Length of data in bytes
* @tag: 16-byte tag value
* Returns: 0 on success, -1 on failure
*/
int aes_128_eax_encrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
const u8 *hdr, size_t hdr_len,
u8 *data, size_t data_len, u8 *tag)
{
u8 *buf;
size_t buf_len;
u8 nonce_mac[BLOCK_SIZE], hdr_mac[BLOCK_SIZE], data_mac[BLOCK_SIZE];
int i, ret = -1;
if (nonce_len > data_len)
buf_len = nonce_len;
else
buf_len = data_len;
if (hdr_len > buf_len)
buf_len = hdr_len;
buf_len += 16;
buf = os_malloc(buf_len);
if (buf == NULL)
return -1;
os_memset(buf, 0, 15);
buf[15] = 0;
os_memcpy(buf + 16, nonce, nonce_len);
if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac))
goto fail;
buf[15] = 1;
os_memcpy(buf + 16, hdr, hdr_len);
if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac))
goto fail;
if (aes_128_ctr_encrypt(key, nonce_mac, data, data_len))
goto fail;
buf[15] = 2;
os_memcpy(buf + 16, data, data_len);
if (omac1_aes_128(key, buf, 16 + data_len, data_mac))
goto fail;
for (i = 0; i < BLOCK_SIZE; i++)
tag[i] = nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i];
ret = 0;
fail:
os_free(buf);
return ret;
}
/**
* aes_128_eax_decrypt - AES-128 EAX mode decryption
* @key: Key for decryption (16 bytes)
* @nonce: Nonce for counter mode
* @nonce_len: Nonce length in bytes
* @hdr: Header data to be authenticity protected
* @hdr_len: Length of the header data bytes
* @data: Data to encrypt in-place
* @data_len: Length of data in bytes
* @tag: 16-byte tag value
* Returns: 0 on success, -1 on failure, -2 if tag does not match
*/
int aes_128_eax_decrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
const u8 *hdr, size_t hdr_len,
u8 *data, size_t data_len, const u8 *tag)
{
u8 *buf;
size_t buf_len;
u8 nonce_mac[BLOCK_SIZE], hdr_mac[BLOCK_SIZE], data_mac[BLOCK_SIZE];
int i;
if (nonce_len > data_len)
buf_len = nonce_len;
else
buf_len = data_len;
if (hdr_len > buf_len)
buf_len = hdr_len;
buf_len += 16;
buf = os_malloc(buf_len);
if (buf == NULL)
return -1;
os_memset(buf, 0, 15);
buf[15] = 0;
os_memcpy(buf + 16, nonce, nonce_len);
if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac)) {
os_free(buf);
return -1;
}
buf[15] = 1;
os_memcpy(buf + 16, hdr, hdr_len);
if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac)) {
os_free(buf);
return -1;
}
buf[15] = 2;
os_memcpy(buf + 16, data, data_len);
if (omac1_aes_128(key, buf, 16 + data_len, data_mac)) {
os_free(buf);
return -1;
}
os_free(buf);
for (i = 0; i < BLOCK_SIZE; i++) {
if (tag[i] != (nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i]))
return -2;
}
return aes_128_ctr_encrypt(key, nonce_mac, data, data_len);
}
#endif /* CONFIG_NO_AES_EAX */
#ifndef CONFIG_NO_AES_CBC
/**
* aes_128_cbc_encrypt - AES-128 CBC encryption
* @key: Encryption key
* @iv: Encryption IV for CBC mode (16 bytes)
* @data: Data to encrypt in-place
* @data_len: Length of data in bytes (must be divisible by 16)
* Returns: 0 on success, -1 on failure
*/
int aes_128_cbc_encrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
{
void *ctx;
u8 cbc[BLOCK_SIZE];
u8 *pos = data;
int i, j, blocks;
ctx = aes_encrypt_init(key, 16);
if (ctx == NULL)
return -1;
os_memcpy(cbc, iv, BLOCK_SIZE);
blocks = data_len / BLOCK_SIZE;
for (i = 0; i < blocks; i++) {
for (j = 0; j < BLOCK_SIZE; j++)
cbc[j] ^= pos[j];
aes_encrypt(ctx, cbc, cbc);
os_memcpy(pos, cbc, BLOCK_SIZE);
pos += BLOCK_SIZE;
}
aes_encrypt_deinit(ctx);
return 0;
}
/**
* aes_128_cbc_decrypt - AES-128 CBC decryption
* @key: Decryption key
* @iv: Decryption IV for CBC mode (16 bytes)
* @data: Data to decrypt in-place
* @data_len: Length of data in bytes (must be divisible by 16)
* Returns: 0 on success, -1 on failure
*/
int aes_128_cbc_decrypt(const u8 *key, const u8 *iv, u8 *data, size_t data_len)
{
void *ctx;
u8 cbc[BLOCK_SIZE], tmp[BLOCK_SIZE];
u8 *pos = data;
int i, j, blocks;
ctx = aes_decrypt_init(key, 16);
if (ctx == NULL)
return -1;
os_memcpy(cbc, iv, BLOCK_SIZE);
blocks = data_len / BLOCK_SIZE;
for (i = 0; i < blocks; i++) {
os_memcpy(tmp, pos, BLOCK_SIZE);
aes_decrypt(ctx, pos, pos);
for (j = 0; j < BLOCK_SIZE; j++)
pos[j] ^= cbc[j];
os_memcpy(cbc, tmp, BLOCK_SIZE);
pos += BLOCK_SIZE;
}
aes_decrypt_deinit(ctx);
return 0;
}
#endif /* CONFIG_NO_AES_CBC */