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qemu/crypto/cipher-builtin.c
Daniel P. Berrange eaec903c5b crypto: wire up XTS mode for cipher APIs 
Introduce 'XTS' as a permitted mode for the cipher APIs.
With XTS the key provided must be twice the size of the
key normally required for any given algorithm. This is
because the key will be split into two pieces for use
in XTS mode.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2016-03-17 14:41:15 +00:00

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/*
* QEMU Crypto cipher built-in algorithms
*
* Copyright (c) 2015 Red Hat, Inc.
*
* This library 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 2 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 library; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include "qemu/osdep.h"
#include "crypto/aes.h"
#include "crypto/desrfb.h"
#include "crypto/xts.h"
typedef struct QCryptoCipherBuiltinAESContext QCryptoCipherBuiltinAESContext;
struct QCryptoCipherBuiltinAESContext {
AES_KEY enc;
AES_KEY dec;
};
typedef struct QCryptoCipherBuiltinAES QCryptoCipherBuiltinAES;
struct QCryptoCipherBuiltinAES {
QCryptoCipherBuiltinAESContext key;
QCryptoCipherBuiltinAESContext key_tweak;
uint8_t iv[AES_BLOCK_SIZE];
};
typedef struct QCryptoCipherBuiltinDESRFB QCryptoCipherBuiltinDESRFB;
struct QCryptoCipherBuiltinDESRFB {
uint8_t *key;
size_t nkey;
};
typedef struct QCryptoCipherBuiltin QCryptoCipherBuiltin;
struct QCryptoCipherBuiltin {
union {
QCryptoCipherBuiltinAES aes;
QCryptoCipherBuiltinDESRFB desrfb;
} state;
size_t blocksize;
void (*free)(QCryptoCipher *cipher);
int (*setiv)(QCryptoCipher *cipher,
const uint8_t *iv, size_t niv,
Error **errp);
int (*encrypt)(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp);
int (*decrypt)(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp);
};
static void qcrypto_cipher_free_aes(QCryptoCipher *cipher)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
g_free(ctxt);
cipher->opaque = NULL;
}
static void qcrypto_cipher_aes_ecb_encrypt(AES_KEY *key,
const void *in,
void *out,
size_t len)
{
const uint8_t *inptr = in;
uint8_t *outptr = out;
while (len) {
if (len > AES_BLOCK_SIZE) {
AES_encrypt(inptr, outptr, key);
inptr += AES_BLOCK_SIZE;
outptr += AES_BLOCK_SIZE;
len -= AES_BLOCK_SIZE;
} else {
uint8_t tmp1[AES_BLOCK_SIZE], tmp2[AES_BLOCK_SIZE];
memcpy(tmp1, inptr, len);
/* Fill with 0 to avoid valgrind uninitialized reads */
memset(tmp1 + len, 0, sizeof(tmp1) - len);
AES_encrypt(tmp1, tmp2, key);
memcpy(outptr, tmp2, len);
len = 0;
}
}
}
static void qcrypto_cipher_aes_ecb_decrypt(AES_KEY *key,
const void *in,
void *out,
size_t len)
{
const uint8_t *inptr = in;
uint8_t *outptr = out;
while (len) {
if (len > AES_BLOCK_SIZE) {
AES_decrypt(inptr, outptr, key);
inptr += AES_BLOCK_SIZE;
outptr += AES_BLOCK_SIZE;
len -= AES_BLOCK_SIZE;
} else {
uint8_t tmp1[AES_BLOCK_SIZE], tmp2[AES_BLOCK_SIZE];
memcpy(tmp1, inptr, len);
/* Fill with 0 to avoid valgrind uninitialized reads */
memset(tmp1 + len, 0, sizeof(tmp1) - len);
AES_decrypt(tmp1, tmp2, key);
memcpy(outptr, tmp2, len);
len = 0;
}
}
}
static void qcrypto_cipher_aes_xts_encrypt(const void *ctx,
size_t length,
uint8_t *dst,
const uint8_t *src)
{
const QCryptoCipherBuiltinAESContext *aesctx = ctx;
qcrypto_cipher_aes_ecb_encrypt((AES_KEY *)&aesctx->enc,
src, dst, length);
}
static void qcrypto_cipher_aes_xts_decrypt(const void *ctx,
size_t length,
uint8_t *dst,
const uint8_t *src)
{
const QCryptoCipherBuiltinAESContext *aesctx = ctx;
qcrypto_cipher_aes_ecb_decrypt((AES_KEY *)&aesctx->dec,
src, dst, length);
}
static int qcrypto_cipher_encrypt_aes(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
switch (cipher->mode) {
case QCRYPTO_CIPHER_MODE_ECB:
qcrypto_cipher_aes_ecb_encrypt(&ctxt->state.aes.key.enc,
in, out, len);
break;
case QCRYPTO_CIPHER_MODE_CBC:
AES_cbc_encrypt(in, out, len,
&ctxt->state.aes.key.enc,
ctxt->state.aes.iv, 1);
break;
case QCRYPTO_CIPHER_MODE_XTS:
xts_encrypt(&ctxt->state.aes.key,
&ctxt->state.aes.key_tweak,
qcrypto_cipher_aes_xts_encrypt,
qcrypto_cipher_aes_xts_decrypt,
ctxt->state.aes.iv,
len, out, in);
break;
default:
g_assert_not_reached();
}
return 0;
}
static int qcrypto_cipher_decrypt_aes(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
switch (cipher->mode) {
case QCRYPTO_CIPHER_MODE_ECB:
qcrypto_cipher_aes_ecb_decrypt(&ctxt->state.aes.key.dec,
in, out, len);
break;
case QCRYPTO_CIPHER_MODE_CBC:
AES_cbc_encrypt(in, out, len,
&ctxt->state.aes.key.dec,
ctxt->state.aes.iv, 0);
break;
case QCRYPTO_CIPHER_MODE_XTS:
xts_decrypt(&ctxt->state.aes.key,
&ctxt->state.aes.key_tweak,
qcrypto_cipher_aes_xts_encrypt,
qcrypto_cipher_aes_xts_decrypt,
ctxt->state.aes.iv,
len, out, in);
break;
default:
g_assert_not_reached();
}
return 0;
}
static int qcrypto_cipher_setiv_aes(QCryptoCipher *cipher,
const uint8_t *iv, size_t niv,
Error **errp)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
if (niv != AES_BLOCK_SIZE) {
error_setg(errp, "IV must be %d bytes not %zu",
AES_BLOCK_SIZE, niv);
return -1;
}
memcpy(ctxt->state.aes.iv, iv, AES_BLOCK_SIZE);
return 0;
}
static int qcrypto_cipher_init_aes(QCryptoCipher *cipher,
const uint8_t *key, size_t nkey,
Error **errp)
{
QCryptoCipherBuiltin *ctxt;
if (cipher->mode != QCRYPTO_CIPHER_MODE_CBC &&
cipher->mode != QCRYPTO_CIPHER_MODE_ECB &&
cipher->mode != QCRYPTO_CIPHER_MODE_XTS) {
error_setg(errp, "Unsupported cipher mode %d", cipher->mode);
return -1;
}
ctxt = g_new0(QCryptoCipherBuiltin, 1);
if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
if (AES_set_encrypt_key(key, nkey * 4, &ctxt->state.aes.key.enc) != 0) {
error_setg(errp, "Failed to set encryption key");
goto error;
}
if (AES_set_decrypt_key(key, nkey * 4, &ctxt->state.aes.key.dec) != 0) {
error_setg(errp, "Failed to set decryption key");
goto error;
}
if (AES_set_encrypt_key(key + (nkey / 2), nkey * 4,
&ctxt->state.aes.key_tweak.enc) != 0) {
error_setg(errp, "Failed to set encryption key");
goto error;
}
if (AES_set_decrypt_key(key + (nkey / 2), nkey * 4,
&ctxt->state.aes.key_tweak.dec) != 0) {
error_setg(errp, "Failed to set decryption key");
goto error;
}
} else {
if (AES_set_encrypt_key(key, nkey * 8, &ctxt->state.aes.key.enc) != 0) {
error_setg(errp, "Failed to set encryption key");
goto error;
}
if (AES_set_decrypt_key(key, nkey * 8, &ctxt->state.aes.key.dec) != 0) {
error_setg(errp, "Failed to set decryption key");
goto error;
}
}
ctxt->blocksize = AES_BLOCK_SIZE;
ctxt->free = qcrypto_cipher_free_aes;
ctxt->setiv = qcrypto_cipher_setiv_aes;
ctxt->encrypt = qcrypto_cipher_encrypt_aes;
ctxt->decrypt = qcrypto_cipher_decrypt_aes;
cipher->opaque = ctxt;
return 0;
error:
g_free(ctxt);
return -1;
}
static void qcrypto_cipher_free_des_rfb(QCryptoCipher *cipher)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
g_free(ctxt->state.desrfb.key);
g_free(ctxt);
cipher->opaque = NULL;
}
static int qcrypto_cipher_encrypt_des_rfb(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
size_t i;
if (len % 8) {
error_setg(errp, "Buffer size must be multiple of 8 not %zu",
len);
return -1;
}
deskey(ctxt->state.desrfb.key, EN0);
for (i = 0; i < len; i += 8) {
des((void *)in + i, out + i);
}
return 0;
}
static int qcrypto_cipher_decrypt_des_rfb(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
size_t i;
if (len % 8) {
error_setg(errp, "Buffer size must be multiple of 8 not %zu",
len);
return -1;
}
deskey(ctxt->state.desrfb.key, DE1);
for (i = 0; i < len; i += 8) {
des((void *)in + i, out + i);
}
return 0;
}
static int qcrypto_cipher_setiv_des_rfb(QCryptoCipher *cipher,
const uint8_t *iv, size_t niv,
Error **errp)
{
error_setg(errp, "Setting IV is not supported");
return -1;
}
static int qcrypto_cipher_init_des_rfb(QCryptoCipher *cipher,
const uint8_t *key, size_t nkey,
Error **errp)
{
QCryptoCipherBuiltin *ctxt;
if (cipher->mode != QCRYPTO_CIPHER_MODE_ECB) {
error_setg(errp, "Unsupported cipher mode %d", cipher->mode);
return -1;
}
ctxt = g_new0(QCryptoCipherBuiltin, 1);
ctxt->state.desrfb.key = g_new0(uint8_t, nkey);
memcpy(ctxt->state.desrfb.key, key, nkey);
ctxt->state.desrfb.nkey = nkey;
ctxt->blocksize = 8;
ctxt->free = qcrypto_cipher_free_des_rfb;
ctxt->setiv = qcrypto_cipher_setiv_des_rfb;
ctxt->encrypt = qcrypto_cipher_encrypt_des_rfb;
ctxt->decrypt = qcrypto_cipher_decrypt_des_rfb;
cipher->opaque = ctxt;
return 0;
}
bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
{
switch (alg) {
case QCRYPTO_CIPHER_ALG_DES_RFB:
case QCRYPTO_CIPHER_ALG_AES_128:
case QCRYPTO_CIPHER_ALG_AES_192:
case QCRYPTO_CIPHER_ALG_AES_256:
return true;
default:
return false;
}
}
QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
QCryptoCipherMode mode,
const uint8_t *key, size_t nkey,
Error **errp)
{
QCryptoCipher *cipher;
cipher = g_new0(QCryptoCipher, 1);
cipher->alg = alg;
cipher->mode = mode;
if (!qcrypto_cipher_validate_key_length(alg, mode, nkey, errp)) {
goto error;
}
switch (cipher->alg) {
case QCRYPTO_CIPHER_ALG_DES_RFB:
if (qcrypto_cipher_init_des_rfb(cipher, key, nkey, errp) < 0) {
goto error;
}
break;
case QCRYPTO_CIPHER_ALG_AES_128:
case QCRYPTO_CIPHER_ALG_AES_192:
case QCRYPTO_CIPHER_ALG_AES_256:
if (qcrypto_cipher_init_aes(cipher, key, nkey, errp) < 0) {
goto error;
}
break;
default:
error_setg(errp,
"Unsupported cipher algorithm %d", cipher->alg);
goto error;
}
return cipher;
error:
g_free(cipher);
return NULL;
}
void qcrypto_cipher_free(QCryptoCipher *cipher)
{
QCryptoCipherBuiltin *ctxt;
if (!cipher) {
return;
}
ctxt = cipher->opaque;
ctxt->free(cipher);
g_free(cipher);
}
int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
if (len % ctxt->blocksize) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctxt->blocksize);
return -1;
}
return ctxt->encrypt(cipher, in, out, len, errp);
}
int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
if (len % ctxt->blocksize) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctxt->blocksize);
return -1;
}
return ctxt->decrypt(cipher, in, out, len, errp);
}
int qcrypto_cipher_setiv(QCryptoCipher *cipher,
const uint8_t *iv, size_t niv,
Error **errp)
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
return ctxt->setiv(cipher, iv, niv, errp);
}
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