/* $NetBSD: gmac.c,v 1.4 2020/06/29 23:34:48 riastradh Exp $ */
/* OpenBSD: gmac.c,v 1.3 2011/01/11 15:44:23 deraadt Exp */
/*
* Copyright (c) 2010 Mike Belopuhov <
[email protected]>
*
* Permission to use, copy, modify, and 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.
*/
/*
* This code implements the Message Authentication part of the
* Galois/Counter Mode (as being described in the RFC 4543) using
* the AES cipher. FIPS SP 800-38D describes the algorithm details.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <crypto/aes/aes.h>
#include <opencrypto/gmac.h>
void ghash_gfmul(const GMAC_INT *, const GMAC_INT *, GMAC_INT *);
void ghash_update(GHASH_CTX *, const uint8_t *, size_t);
/* Computes a block multiplication in the GF(2^128) */
void
ghash_gfmul(const GMAC_INT *X, const GMAC_INT *Y, GMAC_INT *product)
{
GMAC_INT v[GMAC_BLOCK_LEN/GMAC_INTLEN];
uint32_t mul;
int i;
memcpy(v, Y, GMAC_BLOCK_LEN);
memset(product, 0, GMAC_BLOCK_LEN);
for (i = 0; i < GMAC_BLOCK_LEN * 8; i++) {
/* update Z */
#if GMAC_INTLEN == 8
if (X[i >> 6] & (1ULL << (~i & 63))) {
product[0] ^= v[0];
product[1] ^= v[1];
} /* else: we preserve old values */
#else
if (X[i >> 5] & (1 << (~i & 31))) {
product[0] ^= v[0];
product[1] ^= v[1];
product[2] ^= v[2];
product[3] ^= v[3];
} /* else: we preserve old values */
#endif
/* update V */
#if GMAC_INTLEN == 8
mul = v[1] & 1;
v[1] = (v[0] << 63) | (v[1] >> 1);
v[0] = (v[0] >> 1) ^ (0xe100000000000000ULL * mul);
#else
mul = v[3] & 1;
v[3] = (v[2] << 31) | (v[3] >> 1);
v[2] = (v[1] << 31) | (v[2] >> 1);
v[1] = (v[0] << 31) | (v[1] >> 1);
v[0] = (v[0] >> 1) ^ (0xe1000000 * mul);
#endif
}
}
void
ghash_update(GHASH_CTX *ctx, const uint8_t *X, size_t len)
{
GMAC_INT x;
GMAC_INT *s = ctx->S;
GMAC_INT *y = ctx->Z;
int i, j, k;
for (i = 0; i < len / GMAC_BLOCK_LEN; i++) {
for (j = 0; j < GMAC_BLOCK_LEN/GMAC_INTLEN; j++) {
x = 0;
for (k = 0; k < GMAC_INTLEN; k++) {
x <<= 8;
x |= X[k];
}
s[j] = y[j] ^ x;
X += GMAC_INTLEN;
}
ghash_gfmul(ctx->H, ctx->S, ctx->S);
y = s;
}
memcpy(ctx->Z, ctx->S, GMAC_BLOCK_LEN);
}
#define AESCTR_NONCESIZE 4
void
AES_GMAC_Init(AES_GMAC_CTX *ctx)
{
memset(ctx, 0, sizeof(AES_GMAC_CTX));
}
void
AES_GMAC_Setkey(AES_GMAC_CTX *ctx, const uint8_t *key, uint16_t klen)
{
int i;
switch (klen) {
case 16 + AESCTR_NONCESIZE:
ctx->rounds = aes_setenckey128(&ctx->K, key);
break;
case 24 + AESCTR_NONCESIZE:
ctx->rounds = aes_setenckey192(&ctx->K, key);
break;
case 32 + AESCTR_NONCESIZE:
ctx->rounds = aes_setenckey256(&ctx->K, key);
break;
default:
panic("invalid AES_GMAC_Setkey length in bytes: %u",
(unsigned)klen);
}
/* copy out salt to the counter block */
memcpy(ctx->J, key + klen - AESCTR_NONCESIZE, AESCTR_NONCESIZE);
/* prepare a hash subkey */
aes_enc(&ctx->K, (const void *)ctx->ghash.H, (void *)ctx->ghash.H,
ctx->rounds);
#if GMAC_INTLEN == 8
for (i = 0; i < 2; i++)
ctx->ghash.H[i] = be64toh(ctx->ghash.H[i]);
#else
for (i = 0; i < 4; i++)
ctx->ghash.H[i] = be32toh(ctx->ghash.H[i]);
#endif
}
void
AES_GMAC_Reinit(AES_GMAC_CTX *ctx, const uint8_t *iv, uint16_t ivlen)
{
/* copy out IV to the counter block */
memcpy(ctx->J + AESCTR_NONCESIZE, iv, ivlen);
}
int
AES_GMAC_Update(AES_GMAC_CTX *ctx, const uint8_t *data, uint16_t len)
{
uint8_t blk[16] = { 0 };
int plen;
if (len > 0) {
plen = len % GMAC_BLOCK_LEN;
if (len >= GMAC_BLOCK_LEN)
ghash_update(&ctx->ghash, data, len - plen);
if (plen) {
memcpy(blk, data + (len - plen), plen);
ghash_update(&ctx->ghash, blk, GMAC_BLOCK_LEN);
}
}
return (0);
}
void
AES_GMAC_Final(uint8_t digest[GMAC_DIGEST_LEN], AES_GMAC_CTX *ctx)
{
uint8_t keystream[GMAC_BLOCK_LEN], *k, *d;
int i;
/* do one round of GCTR */
ctx->J[GMAC_BLOCK_LEN - 1] = 1;
aes_enc(&ctx->K, ctx->J, keystream, ctx->rounds);
k = keystream;
d = digest;
#if GMAC_INTLEN == 8
for (i = 0; i < GMAC_DIGEST_LEN/8; i++) {
d[0] = (uint8_t)(ctx->ghash.S[i] >> 56) ^ k[0];
d[1] = (uint8_t)(ctx->ghash.S[i] >> 48) ^ k[1];
d[2] = (uint8_t)(ctx->ghash.S[i] >> 40) ^ k[2];
d[3] = (uint8_t)(ctx->ghash.S[i] >> 32) ^ k[3];
d[4] = (uint8_t)(ctx->ghash.S[i] >> 24) ^ k[4];
d[5] = (uint8_t)(ctx->ghash.S[i] >> 16) ^ k[5];
d[6] = (uint8_t)(ctx->ghash.S[i] >> 8) ^ k[6];
d[7] = (uint8_t)ctx->ghash.S[i] ^ k[7];
d += 8;
k += 8;
}
#else
for (i = 0; i < GMAC_DIGEST_LEN/4; i++) {
d[0] = (uint8_t)(ctx->ghash.S[i] >> 24) ^ k[0];
d[1] = (uint8_t)(ctx->ghash.S[i] >> 16) ^ k[1];
d[2] = (uint8_t)(ctx->ghash.S[i] >> 8) ^ k[2];
d[3] = (uint8_t)ctx->ghash.S[i] ^ k[3];
d += 4;
k += 4;
}
#endif
memset(keystream, 0, sizeof(keystream));
}
