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 "qemu/osdep.h"
  22 #include <gcrypt.h>
  23
  24
  25 bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
  26 {
  27     switch (alg) {
  28     case QCRYPTO_CIPHER_ALG_DES_RFB:
  29     case QCRYPTO_CIPHER_ALG_AES_128:
  30     case QCRYPTO_CIPHER_ALG_AES_192:
  31     case QCRYPTO_CIPHER_ALG_AES_256:
  32         return true;
  33     default:
  34         return false;
  35     }
  36 }
  37
  38 typedef struct QCryptoCipherGcrypt QCryptoCipherGcrypt;
  39 struct QCryptoCipherGcrypt {
  40     gcry_cipher_hd_t handle;
  41     size_t blocksize;
  42 };
  43
  44 QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
  45                                   QCryptoCipherMode mode,
  46                                   const uint8_t *key, size_t nkey,
  47                                   Error **errp)
  48 {
  49     QCryptoCipher *cipher;
  50     QCryptoCipherGcrypt *ctx;
  51     gcry_error_t err;
  52     int gcryalg, gcrymode;
  53
  54     switch (mode) {
  55     case QCRYPTO_CIPHER_MODE_ECB:
  56         gcrymode = GCRY_CIPHER_MODE_ECB;
  57         break;
  58     case QCRYPTO_CIPHER_MODE_CBC:
  59         gcrymode = GCRY_CIPHER_MODE_CBC;
  60         break;
  61     default:
  62         error_setg(errp, "Unsupported cipher mode %d", mode);
  63         return NULL;
  64     }
  65
  66     if (!qcrypto_cipher_validate_key_length(alg, nkey, errp)) {
  67         return NULL;
  68     }
  69
  70     switch (alg) {
  71     case QCRYPTO_CIPHER_ALG_DES_RFB:
  72         gcryalg = GCRY_CIPHER_DES;
  73         break;
  74
  75     case QCRYPTO_CIPHER_ALG_AES_128:
  76         gcryalg = GCRY_CIPHER_AES128;
  77         break;
  78
  79     case QCRYPTO_CIPHER_ALG_AES_192:
  80         gcryalg = GCRY_CIPHER_AES192;
  81         break;
  82
  83     case QCRYPTO_CIPHER_ALG_AES_256:
  84         gcryalg = GCRY_CIPHER_AES256;
  85         break;
  86
  87     default:
  88         error_setg(errp, "Unsupported cipher algorithm %d", alg);
  89         return NULL;
  90     }
  91
  92     cipher = g_new0(QCryptoCipher, 1);
  93     cipher->alg = alg;
  94     cipher->mode = mode;
  95
  96     ctx = g_new0(QCryptoCipherGcrypt, 1);
  97
  98     err = gcry_cipher_open(&ctx->handle, gcryalg, gcrymode, 0);
  99     if (err != 0) {
 100         error_setg(errp, "Cannot initialize cipher: %s",
 101                    gcry_strerror(err));
 102         goto error;
 103     }
 104
 105     if (cipher->alg == QCRYPTO_CIPHER_ALG_DES_RFB) {
 106         /* We're using standard DES cipher from gcrypt, so we need
 107          * to munge the key so that the results are the same as the
 108          * bizarre RFB variant of DES :-)
 109          */
 110         uint8_t *rfbkey = qcrypto_cipher_munge_des_rfb_key(key, nkey);
 111         err = gcry_cipher_setkey(ctx->handle, rfbkey, nkey);
 112         g_free(rfbkey);
 113         ctx->blocksize = 8;
 114     } else {
 115         err = gcry_cipher_setkey(ctx->handle, key, nkey);
 116         ctx->blocksize = 16;
 117     }
 118     if (err != 0) {
 119         error_setg(errp, "Cannot set key: %s",
 120                    gcry_strerror(err));
 121         goto error;
 122     }
 123
 124     cipher->opaque = ctx;
 125     return cipher;
 126
 127  error:
 128     gcry_cipher_close(ctx->handle);
 129     g_free(ctx);
 130     g_free(cipher);
 131     return NULL;
 132 }
 133
 134
 135 void qcrypto_cipher_free(QCryptoCipher *cipher)
 136 {
 137     QCryptoCipherGcrypt *ctx;
 138     if (!cipher) {
 139         return;
 140     }
 141     ctx = cipher->opaque;
 142     gcry_cipher_close(ctx->handle);
 143     g_free(ctx);
 144     g_free(cipher);
 145 }
 146
 147
 148 int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
 149                            const void *in,
 150                            void *out,
 151                            size_t len,
 152                            Error **errp)
 153 {
 154     QCryptoCipherGcrypt *ctx = cipher->opaque;
 155     gcry_error_t err;
 156
 157     if (len % ctx->blocksize) {
 158         error_setg(errp, "Length %zu must be a multiple of block size %zu",
 159                    len, ctx->blocksize);
 160         return -1;
 161     }
 162
 163     err = gcry_cipher_encrypt(ctx->handle,
 164                               out, len,
 165                               in, len);
 166     if (err != 0) {
 167         error_setg(errp, "Cannot encrypt data: %s",
 168                    gcry_strerror(err));
 169         return -1;
 170     }
 171
 172     return 0;
 173 }
 174
 175
 176 int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
 177                            const void *in,
 178                            void *out,
 179                            size_t len,
 180                            Error **errp)
 181 {
 182     QCryptoCipherGcrypt *ctx = cipher->opaque;
 183     gcry_error_t err;
 184
 185     if (len % ctx->blocksize) {
 186         error_setg(errp, "Length %zu must be a multiple of block size %zu",
 187                    len, ctx->blocksize);
 188         return -1;
 189     }
 190
 191     err = gcry_cipher_decrypt(ctx->handle,
 192                               out, len,
 193                               in, len);
 194     if (err != 0) {
 195         error_setg(errp, "Cannot decrypt data: %s",
 196                    gcry_strerror(err));
 197         return -1;
 198     }
 199
 200     return 0;
 201 }
 202
 203 int qcrypto_cipher_setiv(QCryptoCipher *cipher,
 204                          const uint8_t *iv, size_t niv,
 205                          Error **errp)
 206 {
 207     QCryptoCipherGcrypt *ctx = cipher->opaque;
 208     gcry_error_t err;
 209
 210     if (niv != ctx->blocksize) {
 211         error_setg(errp, "Expected IV size %zu not %zu",
 212                    ctx->blocksize, niv);
 213         return -1;
 214     }
 215
 216     gcry_cipher_reset(ctx->handle);
 217     err = gcry_cipher_setiv(ctx->handle, iv, niv);
 218     if (err != 0) {
 219         error_setg(errp, "Cannot set IV: %s",
 220                    gcry_strerror(err));
 221         return -1;
 222     }
 223
 224     return 0;
 225 }