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qemu/crypto/cipher-gcrypt.c

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/*
* QEMU Crypto cipher libgcrypt 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/xts.h"
#include <gcrypt.h>
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:
case QCRYPTO_CIPHER_ALG_CAST5_128:
case QCRYPTO_CIPHER_ALG_SERPENT_128:
case QCRYPTO_CIPHER_ALG_SERPENT_192:
case QCRYPTO_CIPHER_ALG_SERPENT_256:
case QCRYPTO_CIPHER_ALG_TWOFISH_128:
case QCRYPTO_CIPHER_ALG_TWOFISH_256:
return true;
default:
return false;
}
}
typedef struct QCryptoCipherGcrypt QCryptoCipherGcrypt;
struct QCryptoCipherGcrypt {
gcry_cipher_hd_t handle;
gcry_cipher_hd_t tweakhandle;
size_t blocksize;
uint8_t *iv;
};
QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
QCryptoCipherMode mode,
const uint8_t *key, size_t nkey,
Error **errp)
{
QCryptoCipher *cipher;
QCryptoCipherGcrypt *ctx;
gcry_error_t err;
int gcryalg, gcrymode;
switch (mode) {
case QCRYPTO_CIPHER_MODE_ECB:
case QCRYPTO_CIPHER_MODE_XTS:
gcrymode = GCRY_CIPHER_MODE_ECB;
break;
case QCRYPTO_CIPHER_MODE_CBC:
gcrymode = GCRY_CIPHER_MODE_CBC;
break;
default:
error_setg(errp, "Unsupported cipher mode %d", mode);
return NULL;
}
if (!qcrypto_cipher_validate_key_length(alg, mode, nkey, errp)) {
return NULL;
}
switch (alg) {
case QCRYPTO_CIPHER_ALG_DES_RFB:
gcryalg = GCRY_CIPHER_DES;
break;
case QCRYPTO_CIPHER_ALG_AES_128:
gcryalg = GCRY_CIPHER_AES128;
break;
case QCRYPTO_CIPHER_ALG_AES_192:
gcryalg = GCRY_CIPHER_AES192;
break;
case QCRYPTO_CIPHER_ALG_AES_256:
gcryalg = GCRY_CIPHER_AES256;
break;
case QCRYPTO_CIPHER_ALG_CAST5_128:
gcryalg = GCRY_CIPHER_CAST5;
break;
case QCRYPTO_CIPHER_ALG_SERPENT_128:
gcryalg = GCRY_CIPHER_SERPENT128;
break;
case QCRYPTO_CIPHER_ALG_SERPENT_192:
gcryalg = GCRY_CIPHER_SERPENT192;
break;
case QCRYPTO_CIPHER_ALG_SERPENT_256:
gcryalg = GCRY_CIPHER_SERPENT256;
break;
case QCRYPTO_CIPHER_ALG_TWOFISH_128:
gcryalg = GCRY_CIPHER_TWOFISH128;
break;
case QCRYPTO_CIPHER_ALG_TWOFISH_256:
gcryalg = GCRY_CIPHER_TWOFISH;
break;
default:
error_setg(errp, "Unsupported cipher algorithm %d", alg);
return NULL;
}
cipher = g_new0(QCryptoCipher, 1);
cipher->alg = alg;
cipher->mode = mode;
ctx = g_new0(QCryptoCipherGcrypt, 1);
err = gcry_cipher_open(&ctx->handle, gcryalg, gcrymode, 0);
if (err != 0) {
error_setg(errp, "Cannot initialize cipher: %s",
gcry_strerror(err));
goto error;
}
if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
err = gcry_cipher_open(&ctx->tweakhandle, gcryalg, gcrymode, 0);
if (err != 0) {
error_setg(errp, "Cannot initialize cipher: %s",
gcry_strerror(err));
goto error;
}
}
if (cipher->alg == QCRYPTO_CIPHER_ALG_DES_RFB) {
/* We're using standard DES cipher from gcrypt, so we need
* to munge the key so that the results are the same as the
* bizarre RFB variant of DES :-)
*/
uint8_t *rfbkey = qcrypto_cipher_munge_des_rfb_key(key, nkey);
err = gcry_cipher_setkey(ctx->handle, rfbkey, nkey);
g_free(rfbkey);
ctx->blocksize = 8;
} else {
if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
nkey /= 2;
err = gcry_cipher_setkey(ctx->handle, key, nkey);
if (err != 0) {
error_setg(errp, "Cannot set key: %s",
gcry_strerror(err));
goto error;
}
err = gcry_cipher_setkey(ctx->tweakhandle, key + nkey, nkey);
} else {
err = gcry_cipher_setkey(ctx->handle, key, nkey);
}
if (err != 0) {
error_setg(errp, "Cannot set key: %s",
gcry_strerror(err));
goto error;
}
switch (cipher->alg) {
case QCRYPTO_CIPHER_ALG_AES_128:
case QCRYPTO_CIPHER_ALG_AES_192:
case QCRYPTO_CIPHER_ALG_AES_256:
case QCRYPTO_CIPHER_ALG_SERPENT_128:
case QCRYPTO_CIPHER_ALG_SERPENT_192:
case QCRYPTO_CIPHER_ALG_SERPENT_256:
case QCRYPTO_CIPHER_ALG_TWOFISH_128:
case QCRYPTO_CIPHER_ALG_TWOFISH_256:
ctx->blocksize = 16;
break;
case QCRYPTO_CIPHER_ALG_CAST5_128:
ctx->blocksize = 8;
break;
default:
g_assert_not_reached();
}
}
if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
ctx->iv = g_new0(uint8_t, ctx->blocksize);
}
cipher->opaque = ctx;
return cipher;
error:
gcry_cipher_close(ctx->handle);
if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
gcry_cipher_close(ctx->tweakhandle);
}
g_free(ctx);
g_free(cipher);
return NULL;
}
void qcrypto_cipher_free(QCryptoCipher *cipher)
{
QCryptoCipherGcrypt *ctx;
if (!cipher) {
return;
}
ctx = cipher->opaque;
gcry_cipher_close(ctx->handle);
if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
gcry_cipher_close(ctx->tweakhandle);
}
g_free(ctx->iv);
g_free(ctx);
g_free(cipher);
}
static void qcrypto_gcrypt_xts_encrypt(const void *ctx,
size_t length,
uint8_t *dst,
const uint8_t *src)
{
gcry_error_t err;
err = gcry_cipher_encrypt((gcry_cipher_hd_t)ctx, dst, length, src, length);
g_assert(err == 0);
}
static void qcrypto_gcrypt_xts_decrypt(const void *ctx,
size_t length,
uint8_t *dst,
const uint8_t *src)
{
gcry_error_t err;
err = gcry_cipher_decrypt((gcry_cipher_hd_t)ctx, dst, length, src, length);
g_assert(err == 0);
}
int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherGcrypt *ctx = cipher->opaque;
gcry_error_t err;
if (len % ctx->blocksize) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;
}
if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
xts_encrypt(ctx->handle, ctx->tweakhandle,
qcrypto_gcrypt_xts_encrypt,
qcrypto_gcrypt_xts_decrypt,
ctx->iv, len, out, in);
} else {
err = gcry_cipher_encrypt(ctx->handle,
out, len,
in, len);
if (err != 0) {
error_setg(errp, "Cannot encrypt data: %s",
gcry_strerror(err));
return -1;
}
}
return 0;
}
int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherGcrypt *ctx = cipher->opaque;
gcry_error_t err;
if (len % ctx->blocksize) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;
}
if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
xts_decrypt(ctx->handle, ctx->tweakhandle,
qcrypto_gcrypt_xts_encrypt,
qcrypto_gcrypt_xts_decrypt,
ctx->iv, len, out, in);
} else {
err = gcry_cipher_decrypt(ctx->handle,
out, len,
in, len);
if (err != 0) {
error_setg(errp, "Cannot decrypt data: %s",
gcry_strerror(err));
return -1;
}
}
return 0;
}
int qcrypto_cipher_setiv(QCryptoCipher *cipher,
const uint8_t *iv, size_t niv,
Error **errp)
{
QCryptoCipherGcrypt *ctx = cipher->opaque;
gcry_error_t err;
if (niv != ctx->blocksize) {
error_setg(errp, "Expected IV size %zu not %zu",
ctx->blocksize, niv);
return -1;
}
if (ctx->iv) {
memcpy(ctx->iv, iv, niv);
} else {
gcry_cipher_reset(ctx->handle);
err = gcry_cipher_setiv(ctx->handle, iv, niv);
if (err != 0) {
error_setg(errp, "Cannot set IV: %s",
gcry_strerror(err));
return -1;
}
}
return 0;
}
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