f90a4542b4
These operations are almost identical, so use common functions to share the same implementation. Signed-hostap: Jouni Malinen <j@w1.fi>
327 lines
6.5 KiB
C
327 lines
6.5 KiB
C
/*
|
|
* Galois/Counter Mode (GCM) and GMAC with AES
|
|
*
|
|
* Copyright (c) 2012, Jouni Malinen <j@w1.fi>
|
|
*
|
|
* This software may be distributed under the terms of the BSD license.
|
|
* See README for more details.
|
|
*/
|
|
|
|
#include "includes.h"
|
|
|
|
#include "common.h"
|
|
#include "aes.h"
|
|
#include "aes_wrap.h"
|
|
|
|
static void inc32(u8 *block)
|
|
{
|
|
u32 val;
|
|
val = WPA_GET_BE32(block + AES_BLOCK_SIZE - 4);
|
|
val++;
|
|
WPA_PUT_BE32(block + AES_BLOCK_SIZE - 4, val);
|
|
}
|
|
|
|
|
|
static void xor_block(u8 *dst, const u8 *src)
|
|
{
|
|
u32 *d = (u32 *) dst;
|
|
u32 *s = (u32 *) src;
|
|
*d++ ^= *s++;
|
|
*d++ ^= *s++;
|
|
*d++ ^= *s++;
|
|
*d++ ^= *s++;
|
|
}
|
|
|
|
|
|
static void shift_right_block(u8 *v)
|
|
{
|
|
u32 val;
|
|
|
|
val = WPA_GET_BE32(v + 12);
|
|
val >>= 1;
|
|
if (v[11] & 0x01)
|
|
val |= 0x80000000;
|
|
WPA_PUT_BE32(v + 12, val);
|
|
|
|
val = WPA_GET_BE32(v + 8);
|
|
val >>= 1;
|
|
if (v[7] & 0x01)
|
|
val |= 0x80000000;
|
|
WPA_PUT_BE32(v + 8, val);
|
|
|
|
val = WPA_GET_BE32(v + 4);
|
|
val >>= 1;
|
|
if (v[3] & 0x01)
|
|
val |= 0x80000000;
|
|
WPA_PUT_BE32(v + 4, val);
|
|
|
|
val = WPA_GET_BE32(v);
|
|
val >>= 1;
|
|
WPA_PUT_BE32(v, val);
|
|
}
|
|
|
|
|
|
/* Multiplication in GF(2^128) */
|
|
static void gf_mult(const u8 *x, const u8 *y, u8 *z)
|
|
{
|
|
u8 v[16];
|
|
int i, j;
|
|
|
|
os_memset(z, 0, 16); /* Z_0 = 0^128 */
|
|
os_memcpy(v, y, 16); /* V_0 = Y */
|
|
|
|
for (i = 0; i < 16; i++) {
|
|
for (j = 0; j < 8; j++) {
|
|
if (x[i] & BIT(7 - j)) {
|
|
/* Z_(i + 1) = Z_i XOR V_i */
|
|
xor_block(z, v);
|
|
} else {
|
|
/* Z_(i + 1) = Z_i */
|
|
}
|
|
|
|
if (v[15] & 0x01) {
|
|
/* V_(i + 1) = (V_i >> 1) XOR R */
|
|
shift_right_block(v);
|
|
/* R = 11100001 || 0^120 */
|
|
v[0] ^= 0xe1;
|
|
} else {
|
|
/* V_(i + 1) = V_i >> 1 */
|
|
shift_right_block(v);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
static void ghash_start(u8 *y)
|
|
{
|
|
/* Y_0 = 0^128 */
|
|
os_memset(y, 0, 16);
|
|
}
|
|
|
|
|
|
static void ghash(const u8 *h, const u8 *x, size_t xlen, u8 *y)
|
|
{
|
|
size_t m, i;
|
|
const u8 *xpos = x;
|
|
u8 tmp[16];
|
|
|
|
m = xlen / 16;
|
|
|
|
for (i = 0; i < m; i++) {
|
|
/* Y_i = (Y^(i-1) XOR X_i) dot H */
|
|
xor_block(y, xpos);
|
|
xpos += 16;
|
|
|
|
/* dot operation:
|
|
* multiplication operation for binary Galois (finite) field of
|
|
* 2^128 elements */
|
|
gf_mult(y, h, tmp);
|
|
os_memcpy(y, tmp, 16);
|
|
}
|
|
|
|
if (x + xlen > xpos) {
|
|
/* Add zero padded last block */
|
|
size_t last = x + xlen - xpos;
|
|
os_memcpy(tmp, xpos, last);
|
|
os_memset(tmp + last, 0, sizeof(tmp) - last);
|
|
|
|
/* Y_i = (Y^(i-1) XOR X_i) dot H */
|
|
xor_block(y, tmp);
|
|
|
|
/* dot operation:
|
|
* multiplication operation for binary Galois (finite) field of
|
|
* 2^128 elements */
|
|
gf_mult(y, h, tmp);
|
|
os_memcpy(y, tmp, 16);
|
|
}
|
|
|
|
/* Return Y_m */
|
|
}
|
|
|
|
|
|
static void aes_gctr(void *aes, const u8 *icb, const u8 *x, size_t xlen, u8 *y)
|
|
{
|
|
size_t i, n, last;
|
|
u8 cb[AES_BLOCK_SIZE], tmp[AES_BLOCK_SIZE];
|
|
const u8 *xpos = x;
|
|
u8 *ypos = y;
|
|
|
|
if (xlen == 0)
|
|
return;
|
|
|
|
n = xlen / 16;
|
|
|
|
os_memcpy(cb, icb, AES_BLOCK_SIZE);
|
|
/* Full blocks */
|
|
for (i = 0; i < n; i++) {
|
|
aes_encrypt(aes, cb, ypos);
|
|
xor_block(ypos, xpos);
|
|
xpos += AES_BLOCK_SIZE;
|
|
ypos += AES_BLOCK_SIZE;
|
|
inc32(cb);
|
|
}
|
|
|
|
last = x + xlen - xpos;
|
|
if (last) {
|
|
/* Last, partial block */
|
|
aes_encrypt(aes, cb, tmp);
|
|
for (i = 0; i < last; i++)
|
|
*ypos++ = *xpos++ ^ tmp[i];
|
|
}
|
|
}
|
|
|
|
|
|
static void * aes_gcm_init_hash_subkey(const u8 *key, size_t key_len, u8 *H)
|
|
{
|
|
void *aes;
|
|
|
|
aes = aes_encrypt_init(key, key_len);
|
|
if (aes == NULL)
|
|
return NULL;
|
|
|
|
/* Generate hash subkey H = AES_K(0^128) */
|
|
os_memset(H, 0, AES_BLOCK_SIZE);
|
|
aes_encrypt(aes, H, H);
|
|
wpa_hexdump_key(MSG_EXCESSIVE, "Hash subkey H for GHASH",
|
|
H, AES_BLOCK_SIZE);
|
|
return aes;
|
|
}
|
|
|
|
|
|
static void aes_gcm_prepare_j0(const u8 *iv, size_t iv_len, const u8 *H, u8 *J0)
|
|
{
|
|
u8 len_buf[16];
|
|
|
|
if (iv_len == 12) {
|
|
/* Prepare block J_0 = IV || 0^31 || 1 [len(IV) = 96] */
|
|
os_memcpy(J0, iv, iv_len);
|
|
os_memset(J0 + iv_len, 0, AES_BLOCK_SIZE - iv_len);
|
|
J0[AES_BLOCK_SIZE - 1] = 0x01;
|
|
} else {
|
|
/*
|
|
* s = 128 * ceil(len(IV)/128) - len(IV)
|
|
* J_0 = GHASH_H(IV || 0^(s+64) || [len(IV)]_64)
|
|
*/
|
|
ghash_start(J0);
|
|
ghash(H, iv, iv_len, J0);
|
|
WPA_PUT_BE64(len_buf, 0);
|
|
WPA_PUT_BE64(len_buf + 8, iv_len * 8);
|
|
ghash(H, len_buf, sizeof(len_buf), J0);
|
|
}
|
|
}
|
|
|
|
|
|
static void aes_gcm_gctr(void *aes, const u8 *J0, const u8 *in, size_t len,
|
|
u8 *out)
|
|
{
|
|
u8 J0inc[AES_BLOCK_SIZE];
|
|
|
|
if (len == 0)
|
|
return;
|
|
|
|
os_memcpy(J0inc, J0, AES_BLOCK_SIZE);
|
|
inc32(J0inc);
|
|
aes_gctr(aes, J0inc, in, len, out);
|
|
}
|
|
|
|
|
|
static void aes_gcm_ghash(const u8 *H, const u8 *aad, size_t aad_len,
|
|
const u8 *crypt, size_t crypt_len, u8 *S)
|
|
{
|
|
u8 len_buf[16];
|
|
|
|
/*
|
|
* u = 128 * ceil[len(C)/128] - len(C)
|
|
* v = 128 * ceil[len(A)/128] - len(A)
|
|
* S = GHASH_H(A || 0^v || C || 0^u || [len(A)]64 || [len(C)]64)
|
|
* (i.e., zero padded to block size A || C and lengths of each in bits)
|
|
*/
|
|
ghash_start(S);
|
|
ghash(H, aad, aad_len, S);
|
|
ghash(H, crypt, crypt_len, S);
|
|
WPA_PUT_BE64(len_buf, aad_len * 8);
|
|
WPA_PUT_BE64(len_buf + 8, crypt_len * 8);
|
|
ghash(H, len_buf, sizeof(len_buf), S);
|
|
|
|
wpa_hexdump_key(MSG_EXCESSIVE, "S = GHASH_H(...)", S, 16);
|
|
}
|
|
|
|
|
|
/**
|
|
* aes_gcm_ae - GCM-AE_K(IV, P, A)
|
|
*/
|
|
int aes_gcm_ae(const u8 *key, size_t key_len, const u8 *iv, size_t iv_len,
|
|
const u8 *plain, size_t plain_len,
|
|
const u8 *aad, size_t aad_len, u8 *crypt, u8 *tag)
|
|
{
|
|
u8 H[AES_BLOCK_SIZE];
|
|
u8 J0[AES_BLOCK_SIZE];
|
|
u8 S[16];
|
|
void *aes;
|
|
|
|
aes = aes_gcm_init_hash_subkey(key, key_len, H);
|
|
if (aes == NULL)
|
|
return -1;
|
|
|
|
aes_gcm_prepare_j0(iv, iv_len, H, J0);
|
|
|
|
/* C = GCTR_K(inc_32(J_0), P) */
|
|
aes_gcm_gctr(aes, J0, plain, plain_len, crypt);
|
|
|
|
aes_gcm_ghash(H, aad, aad_len, crypt, plain_len, S);
|
|
|
|
/* T = MSB_t(GCTR_K(J_0, S)) */
|
|
aes_gctr(aes, J0, S, sizeof(S), tag);
|
|
|
|
/* Return (C, T) */
|
|
|
|
aes_encrypt_deinit(aes);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/**
|
|
* aes_gcm_ad - GCM-AD_K(IV, C, A, T)
|
|
*/
|
|
int aes_gcm_ad(const u8 *key, size_t key_len, const u8 *iv, size_t iv_len,
|
|
const u8 *crypt, size_t crypt_len,
|
|
const u8 *aad, size_t aad_len, const u8 *tag, u8 *plain)
|
|
{
|
|
u8 H[AES_BLOCK_SIZE];
|
|
u8 J0[AES_BLOCK_SIZE];
|
|
u8 S[16], T[16];
|
|
void *aes;
|
|
|
|
aes = aes_gcm_init_hash_subkey(key, key_len, H);
|
|
if (aes == NULL)
|
|
return -1;
|
|
|
|
aes_gcm_prepare_j0(iv, iv_len, H, J0);
|
|
|
|
/* P = GCTR_K(inc_32(J_0), C) */
|
|
aes_gcm_gctr(aes, J0, crypt, crypt_len, plain);
|
|
|
|
aes_gcm_ghash(H, aad, aad_len, crypt, crypt_len, S);
|
|
|
|
/* T' = MSB_t(GCTR_K(J_0, S)) */
|
|
aes_gctr(aes, J0, S, sizeof(S), T);
|
|
|
|
aes_encrypt_deinit(aes);
|
|
|
|
if (os_memcmp(tag, T, 16) != 0) {
|
|
wpa_printf(MSG_EXCESSIVE, "GCM: Tag mismatch");
|
|
return -1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
int aes_gmac(const u8 *key, size_t key_len, const u8 *iv, size_t iv_len,
|
|
const u8 *aad, size_t aad_len, u8 *tag)
|
|
{
|
|
return aes_gcm_ae(key, key_len, iv, iv_len, NULL, 0, aad, aad_len, NULL,
|
|
tag);
|
|
}
|