/*
* Copyright (C) 2011 Free Software Foundation, Inc.
*
* Author: Nikos Mavrogiannopoulos
*
* This file is part of GnuTLS.
*
* The GnuTLS is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 3 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see
*
*/
/*
* The following code is an implementation of the AES-128-CBC cipher
* using intel's AES instruction set. It is based on Intel reference
* code.
*/
#include
#include
#include
#include
#include
#include
#include
#define GCM_BLOCK_SIZE 16
/* GCM mode */
typedef struct
{
uint64_t hi, lo;
} u128;
/* This is the gcm128 structure used in openssl. It
* is compatible with the included assembly code.
*/
struct gcm128_context
{
union
{
uint64_t u[2];
uint32_t d[4];
uint8_t c[16];
} Yi, EKi, EK0, len, Xi, H;
u128 Htable[16];
};
struct aes_gcm_ctx
{
AES_KEY expanded_key;
struct gcm128_context gcm;
};
void gcm_init_clmul (u128 Htable[16], const u64 Xi[2]);
void gcm_ghash_clmul (uint64_t Xi[2], const u128 Htable[16],
const uint8_t * inp, size_t len);
void gcm_gmult_clmul (u64 Xi[2], const u128 Htable[16]);
static void
aes_gcm_deinit (void *_ctx)
{
gnutls_free (_ctx);
}
static int
aes_gcm_cipher_init (gnutls_cipher_algorithm_t algorithm, void **_ctx, int enc)
{
/* we use key size to distinguish */
if (algorithm != GNUTLS_CIPHER_AES_128_GCM &&
algorithm != GNUTLS_CIPHER_AES_256_GCM)
return GNUTLS_E_INVALID_REQUEST;
*_ctx = gnutls_calloc (1, sizeof (struct aes_gcm_ctx));
if (*_ctx == NULL)
{
gnutls_assert ();
return GNUTLS_E_MEMORY_ERROR;
}
return 0;
}
static int
aes_gcm_cipher_setkey (void *_ctx, const void *userkey, size_t keysize)
{
struct aes_gcm_ctx *ctx = _ctx;
int ret;
ret = aesni_set_encrypt_key (userkey, keysize * 8, ALIGN16(&ctx->expanded_key));
if (ret != 0)
return gnutls_assert_val (GNUTLS_E_ENCRYPTION_FAILED);
aesni_ecb_encrypt (ctx->gcm.H.c, ctx->gcm.H.c,
GCM_BLOCK_SIZE, ALIGN16(&ctx->expanded_key), 1);
ctx->gcm.H.u[0] = bswap_64 (ctx->gcm.H.u[0]);
ctx->gcm.H.u[1] = bswap_64 (ctx->gcm.H.u[1]);
gcm_init_clmul (ctx->gcm.Htable, ctx->gcm.H.u);
return 0;
}
static int
aes_gcm_setiv (void *_ctx, const void *iv, size_t iv_size)
{
struct aes_gcm_ctx *ctx = _ctx;
if (iv_size != GCM_BLOCK_SIZE - 4)
return GNUTLS_E_INVALID_REQUEST;
memset (ctx->gcm.Xi.c, 0, sizeof (ctx->gcm.Xi.c));
memset (ctx->gcm.len.c, 0, sizeof (ctx->gcm.len.c));
memcpy (ctx->gcm.Yi.c, iv, GCM_BLOCK_SIZE - 4);
ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 4] = 0;
ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 3] = 0;
ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 2] = 0;
ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 1] = 1;
aesni_ecb_encrypt (ctx->gcm.Yi.c, ctx->gcm.EK0.c,
GCM_BLOCK_SIZE, ALIGN16(&ctx->expanded_key), 1);
ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 1] = 2;
return 0;
}
static void
gcm_ghash (struct aes_gcm_ctx *ctx, const uint8_t * src, size_t src_size)
{
size_t rest = src_size % GCM_BLOCK_SIZE;
size_t aligned_size = src_size - rest;
if (aligned_size > 0)
gcm_ghash_clmul (ctx->gcm.Xi.u, ctx->gcm.Htable, src, aligned_size);
if (rest > 0)
{
memxor (ctx->gcm.Xi.c, src + aligned_size, rest);
gcm_gmult_clmul (ctx->gcm.Xi.u, ctx->gcm.Htable);
}
}
static inline void
ctr_encrypt_last (struct aes_gcm_ctx *ctx, const uint8_t * src,
uint8_t * dst, size_t pos, size_t length)
{
uint8_t tmp[GCM_BLOCK_SIZE];
uint8_t out[GCM_BLOCK_SIZE];
memcpy (tmp, &src[pos], length);
aesni_ctr32_encrypt_blocks (tmp, out, 1, ALIGN16(&ctx->expanded_key), ctx->gcm.Yi.c);
memcpy (&dst[pos], out, length);
}
static int
aes_gcm_encrypt (void *_ctx, const void *src, size_t src_size,
void *dst, size_t length)
{
struct aes_gcm_ctx *ctx = _ctx;
int blocks = src_size / GCM_BLOCK_SIZE;
int exp_blocks = blocks * GCM_BLOCK_SIZE;
int rest = src_size - (exp_blocks);
uint32_t counter;
if (blocks > 0)
{
aesni_ctr32_encrypt_blocks (src, dst,
blocks, ALIGN16(&ctx->expanded_key),
ctx->gcm.Yi.c);
counter = _gnutls_read_uint32 (ctx->gcm.Yi.c + 12);
counter += blocks;
_gnutls_write_uint32 (counter, ctx->gcm.Yi.c + 12);
}
if (rest > 0) /* last incomplete block */
ctr_encrypt_last (ctx, src, dst, exp_blocks, rest);
gcm_ghash (ctx, dst, src_size);
ctx->gcm.len.u[1] += src_size;
return 0;
}
static int
aes_gcm_decrypt (void *_ctx, const void *src, size_t src_size,
void *dst, size_t dst_size)
{
struct aes_gcm_ctx *ctx = _ctx;
int blocks = src_size / GCM_BLOCK_SIZE;
int exp_blocks = blocks * GCM_BLOCK_SIZE;
int rest = src_size - (exp_blocks);
uint32_t counter;
gcm_ghash (ctx, src, src_size);
ctx->gcm.len.u[1] += src_size;
if (blocks > 0)
{
aesni_ctr32_encrypt_blocks (src, dst,
blocks, ALIGN16(&ctx->expanded_key),
ctx->gcm.Yi.c);
counter = _gnutls_read_uint32 (ctx->gcm.Yi.c + 12);
counter += blocks;
_gnutls_write_uint32 (counter, ctx->gcm.Yi.c + 12);
}
if (rest > 0) /* last incomplete block */
ctr_encrypt_last (ctx, src, dst, exp_blocks, rest);
return 0;
}
static int
aes_gcm_auth (void *_ctx, const void *src, size_t src_size)
{
struct aes_gcm_ctx *ctx = _ctx;
gcm_ghash (ctx, src, src_size);
ctx->gcm.len.u[0] += src_size;
return 0;
}
static void
aes_gcm_tag (void *_ctx, void *tag, size_t tagsize)
{
struct aes_gcm_ctx *ctx = _ctx;
uint8_t buffer[GCM_BLOCK_SIZE];
uint64_t alen, clen;
alen = ctx->gcm.len.u[0] * 8;
clen = ctx->gcm.len.u[1] * 8;
_gnutls_write_uint64 (alen, buffer);
_gnutls_write_uint64 (clen, &buffer[8]);
gcm_ghash_clmul (ctx->gcm.Xi.u, ctx->gcm.Htable, buffer, GCM_BLOCK_SIZE);
ctx->gcm.Xi.u[0] ^= ctx->gcm.EK0.u[0];
ctx->gcm.Xi.u[1] ^= ctx->gcm.EK0.u[1];
memcpy (tag, ctx->gcm.Xi.c, MIN (GCM_BLOCK_SIZE, tagsize));
}
const gnutls_crypto_cipher_st aes_gcm_struct = {
.init = aes_gcm_cipher_init,
.setkey = aes_gcm_cipher_setkey,
.setiv = aes_gcm_setiv,
.encrypt = aes_gcm_encrypt,
.decrypt = aes_gcm_decrypt,
.deinit = aes_gcm_deinit,
.tag = aes_gcm_tag,
.auth = aes_gcm_auth,
};