crypto/cipher-gcrypt.c

   1 /*
   2  * QEMU Crypto cipher libgcrypt algorithms
   3  *
   4  * Copyright (c) 2015 Red Hat, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include <gcrypt.h>
  22
  23
  24 bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
  25 {
  26     switch (alg) {
  27     case QCRYPTO_CIPHER_ALG_DES_RFB:
  28     case QCRYPTO_CIPHER_ALG_AES_128:
  29     case QCRYPTO_CIPHER_ALG_AES_192:
  30     case QCRYPTO_CIPHER_ALG_AES_256:
  31         return true;
  32     default:
  33         return false;
  34     }
  35 }
  36
  37 typedef struct QCryptoCipherGcrypt QCryptoCipherGcrypt;
  38 struct QCryptoCipherGcrypt {
  39     gcry_cipher_hd_t handle;
  40     size_t blocksize;
  41 };
  42
  43 QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
  44                                   QCryptoCipherMode mode,
  45                                   const uint8_t *key, size_t nkey,
  46                                   Error **errp)
  47 {
  48     QCryptoCipher *cipher;
  49     QCryptoCipherGcrypt *ctx;
  50     gcry_error_t err;
  51     int gcryalg, gcrymode;
  52
  53     switch (mode) {
  54     case QCRYPTO_CIPHER_MODE_ECB:
  55         gcrymode = GCRY_CIPHER_MODE_ECB;
  56         break;
  57     case QCRYPTO_CIPHER_MODE_CBC:
  58         gcrymode = GCRY_CIPHER_MODE_CBC;
  59         break;
  60     default:
  61         error_setg(errp, "Unsupported cipher mode %d", mode);
  62         return NULL;
  63     }
  64
  65     if (!qcrypto_cipher_validate_key_length(alg, nkey, errp)) {
  66         return NULL;
  67     }
  68
  69     switch (alg) {
  70     case QCRYPTO_CIPHER_ALG_DES_RFB:
  71         gcryalg = GCRY_CIPHER_DES;
  72         break;
  73
  74     case QCRYPTO_CIPHER_ALG_AES_128:
  75         gcryalg = GCRY_CIPHER_AES128;
  76         break;
  77
  78     case QCRYPTO_CIPHER_ALG_AES_192:
  79         gcryalg = GCRY_CIPHER_AES192;
  80         break;
  81
  82     case QCRYPTO_CIPHER_ALG_AES_256:
  83         gcryalg = GCRY_CIPHER_AES256;
  84         break;
  85
  86     default:
  87         error_setg(errp, "Unsupported cipher algorithm %d", alg);
  88         return NULL;
  89     }
  90
  91     cipher = g_new0(QCryptoCipher, 1);
  92     cipher->alg = alg;
  93     cipher->mode = mode;
  94
  95     ctx = g_new0(QCryptoCipherGcrypt, 1);
  96
  97     err = gcry_cipher_open(&ctx->handle, gcryalg, gcrymode, 0);
  98     if (err != 0) {
  99         error_setg(errp, "Cannot initialize cipher: %s",
 100                    gcry_strerror(err));
 101         goto error;
 102     }
 103
 104     if (cipher->alg == QCRYPTO_CIPHER_ALG_DES_RFB) {
 105         /* We're using standard DES cipher from gcrypt, so we need
 106          * to munge the key so that the results are the same as the
 107          * bizarre RFB variant of DES :-)
 108          */
 109         uint8_t *rfbkey = qcrypto_cipher_munge_des_rfb_key(key, nkey);
 110         err = gcry_cipher_setkey(ctx->handle, rfbkey, nkey);
 111         g_free(rfbkey);
 112         ctx->blocksize = 8;
 113     } else {
 114         err = gcry_cipher_setkey(ctx->handle, key, nkey);
 115         ctx->blocksize = 16;
 116     }
 117     if (err != 0) {
 118         error_setg(errp, "Cannot set key: %s",
 119                    gcry_strerror(err));
 120         goto error;
 121     }
 122
 123     cipher->opaque = ctx;
 124     return cipher;
 125
 126  error:
 127     gcry_cipher_close(ctx->handle);
 128     g_free(ctx);
 129     g_free(cipher);
 130     return NULL;
 131 }
 132
 133
 134 void qcrypto_cipher_free(QCryptoCipher *cipher)
 135 {
 136     QCryptoCipherGcrypt *ctx;
 137     if (!cipher) {
 138         return;
 139     }
 140     ctx = cipher->opaque;
 141     gcry_cipher_close(ctx->handle);
 142     g_free(ctx);
 143     g_free(cipher);
 144 }
 145
 146
 147 int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
 148                            const void *in,
 149                            void *out,
 150                            size_t len,
 151                            Error **errp)
 152 {
 153     QCryptoCipherGcrypt *ctx = cipher->opaque;
 154     gcry_error_t err;
 155
 156     if (len % ctx->blocksize) {
 157         error_setg(errp, "Length %zu must be a multiple of block size %zu",
 158                    len, ctx->blocksize);
 159         return -1;
 160     }
 161
 162     err = gcry_cipher_encrypt(ctx->handle,
 163                               out, len,
 164                               in, len);
 165     if (err != 0) {
 166         error_setg(errp, "Cannot encrypt data: %s",
 167                    gcry_strerror(err));
 168         return -1;
 169     }
 170
 171     return 0;
 172 }
 173
 174
 175 int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
 176                            const void *in,
 177                            void *out,
 178                            size_t len,
 179                            Error **errp)
 180 {
 181     QCryptoCipherGcrypt *ctx = cipher->opaque;
 182     gcry_error_t err;
 183
 184     if (len % ctx->blocksize) {
 185         error_setg(errp, "Length %zu must be a multiple of block size %zu",
 186                    len, ctx->blocksize);
 187         return -1;
 188     }
 189
 190     err = gcry_cipher_decrypt(ctx->handle,
 191                               out, len,
 192                               in, len);
 193     if (err != 0) {
 194         error_setg(errp, "Cannot decrypt data: %s",
 195                    gcry_strerror(err));
 196         return -1;
 197     }
 198
 199     return 0;
 200 }
 201
 202 int qcrypto_cipher_setiv(QCryptoCipher *cipher,
 203                          const uint8_t *iv, size_t niv,
 204                          Error **errp)
 205 {
 206     QCryptoCipherGcrypt *ctx = cipher->opaque;
 207     gcry_error_t err;
 208
 209     if (niv != ctx->blocksize) {
 210         error_setg(errp, "Expected IV size %zu not %zu",
 211                    ctx->blocksize, niv);
 212         return -1;
 213     }
 214
 215     gcry_cipher_reset(ctx->handle);
 216     err = gcry_cipher_setiv(ctx->handle, iv, niv);
 217     if (err != 0) {
 218         error_setg(errp, "Cannot set IV: %s",
 219                    gcry_strerror(err));
 220         return -1;
 221     }
 222
 223     return 0;
 224 }