[Qemu-devel] [PATCH v4 06/26] crypto: add support for the cast5-128 cipher algorithm

["Daniel P. Berrange" <berrange@redhat.com>]

A new cipher algorithm 'cast-5-128' is defined for the
Cast-5 algorithm with 128 bit key size. Smaller key sizes
are supported by Cast-5, but nothing in QEMU should use
them, so only 128 bit keys are permitted.

The nettle and gcrypt cipher backends are updated to
support the new cipher and a test vector added to the
cipher test suite. The new algorithm is enabled in the
LUKS block encryption driver.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 crypto/cipher-gcrypt.c     | 18 +++++++++++++++++-
 crypto/cipher-nettle.c     | 26 ++++++++++++++++++++++++++
 crypto/cipher.c            |  2 ++
 qapi/crypto.json           |  5 ++++-
 tests/test-crypto-cipher.c |  9 +++++++++
 5 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/crypto/cipher-gcrypt.c b/crypto/cipher-gcrypt.c
index 56d4c9d..aa1d8c5 100644
--- a/crypto/cipher-gcrypt.c
+++ b/crypto/cipher-gcrypt.c
@@ -29,6 +29,7 @@ bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
     case QCRYPTO_CIPHER_ALG_AES_128:
     case QCRYPTO_CIPHER_ALG_AES_192:
     case QCRYPTO_CIPHER_ALG_AES_256:
+    case QCRYPTO_CIPHER_ALG_CAST5_128:
         return true;
     default:
         return false;
@@ -84,6 +85,10 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
         gcryalg = GCRY_CIPHER_AES256;
         break;
 
+    case QCRYPTO_CIPHER_ALG_CAST5_128:
+        gcryalg = GCRY_CIPHER_CAST5;
+        break;
+
     default:
         error_setg(errp, "Unsupported cipher algorithm %d", alg);
         return NULL;
@@ -113,7 +118,18 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
         ctx->blocksize = 8;
     } else {
         err = gcry_cipher_setkey(ctx->handle, key, nkey);
-        ctx->blocksize = 16;
+        switch (cipher->alg) {
+        case QCRYPTO_CIPHER_ALG_AES_128:
+        case QCRYPTO_CIPHER_ALG_AES_192:
+        case QCRYPTO_CIPHER_ALG_AES_256:
+            ctx->blocksize = 16;
+            break;
+        case QCRYPTO_CIPHER_ALG_CAST5_128:
+            ctx->blocksize = 8;
+            break;
+        default:
+            g_assert_not_reached();
+        }
     }
     if (err != 0) {
         error_setg(errp, "Cannot set key: %s",
diff --git a/crypto/cipher-nettle.c b/crypto/cipher-nettle.c
index cd2675c..cfa69cc 100644
--- a/crypto/cipher-nettle.c
+++ b/crypto/cipher-nettle.c
@@ -23,6 +23,7 @@
 #include <nettle/aes.h>
 #include <nettle/des.h>
 #include <nettle/cbc.h>
+#include <nettle/cast128.h>
 
 #if CONFIG_NETTLE_VERSION_MAJOR < 3
 typedef nettle_crypt_func nettle_cipher_func;
@@ -63,6 +64,18 @@ static void des_decrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
     des_decrypt(ctx, length, dst, src);
 }
 
+static void cast128_encrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
+                                    uint8_t *dst, const uint8_t *src)
+{
+    cast128_encrypt(ctx, length, dst, src);
+}
+
+static void cast128_decrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
+                                    uint8_t *dst, const uint8_t *src)
+{
+    cast128_decrypt(ctx, length, dst, src);
+}
+
 typedef struct QCryptoCipherNettle QCryptoCipherNettle;
 struct QCryptoCipherNettle {
     void *ctx_encrypt;
@@ -80,6 +93,7 @@ bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
     case QCRYPTO_CIPHER_ALG_AES_128:
     case QCRYPTO_CIPHER_ALG_AES_192:
     case QCRYPTO_CIPHER_ALG_AES_256:
+    case QCRYPTO_CIPHER_ALG_CAST5_128:
         return true;
     default:
         return false;
@@ -143,6 +157,18 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
 
         ctx->blocksize = AES_BLOCK_SIZE;
         break;
+
+    case QCRYPTO_CIPHER_ALG_CAST5_128:
+        ctx->ctx_encrypt = g_new0(struct cast128_ctx, 1);
+        ctx->ctx_decrypt = NULL; /* 1 ctx can do both */
+
+        cast5_set_key(ctx->ctx_encrypt, nkey, key);
+
+        ctx->alg_encrypt = cast128_encrypt_wrapper;
+        ctx->alg_decrypt = cast128_decrypt_wrapper;
+
+        ctx->blocksize = CAST128_BLOCK_SIZE;
+        break;
     default:
         error_setg(errp, "Unsupported cipher algorithm %d", alg);
         goto error;
diff --git a/crypto/cipher.c b/crypto/cipher.c
index 076dff0..9e0a226 100644
--- a/crypto/cipher.c
+++ b/crypto/cipher.c
@@ -27,6 +27,7 @@ static size_t alg_key_len[QCRYPTO_CIPHER_ALG__MAX] = {
     [QCRYPTO_CIPHER_ALG_AES_192] = 24,
     [QCRYPTO_CIPHER_ALG_AES_256] = 32,
     [QCRYPTO_CIPHER_ALG_DES_RFB] = 8,
+    [QCRYPTO_CIPHER_ALG_CAST5_128] = 16,
 };
 
 static size_t alg_block_len[QCRYPTO_CIPHER_ALG__MAX] = {
@@ -34,6 +35,7 @@ static size_t alg_block_len[QCRYPTO_CIPHER_ALG__MAX] = {
     [QCRYPTO_CIPHER_ALG_AES_192] = 16,
     [QCRYPTO_CIPHER_ALG_AES_256] = 16,
     [QCRYPTO_CIPHER_ALG_DES_RFB] = 8,
+    [QCRYPTO_CIPHER_ALG_CAST5_128] = 8,
 };
 
 static bool mode_need_iv[QCRYPTO_CIPHER_MODE__MAX] = {
diff --git a/qapi/crypto.json b/qapi/crypto.json
index 42b979a..0550ee7 100644
--- a/qapi/crypto.json
+++ b/qapi/crypto.json
@@ -59,11 +59,14 @@
 # @aes-192: AES with 192 bit / 24 byte keys
 # @aes-256: AES with 256 bit / 32 byte keys
 # @des-rfb: RFB specific variant of single DES. Do not use except in VNC.
+# @cast5-128: Cast5 with 128 bit / 16 byte keys
 # Since: 2.6
 ##
 { 'enum': 'QCryptoCipherAlgorithm',
   'prefix': 'QCRYPTO_CIPHER_ALG',
-  'data': ['aes-128', 'aes-192', 'aes-256', 'des-rfb']}
+  'data': ['aes-128', 'aes-192', 'aes-256',
+           'des-rfb',
+           'cast5-128']}
 
 
 ##
diff --git a/tests/test-crypto-cipher.c b/tests/test-crypto-cipher.c
index 7a073e9..a994ca9 100644
--- a/tests/test-crypto-cipher.c
+++ b/tests/test-crypto-cipher.c
@@ -165,6 +165,15 @@ static QCryptoCipherTestData test_data[] = {
             "ffd29f1bb5596ad94ea2d8e6196b7f09"
             "30d8ed0bf2773af36dd82a6280c20926",
     },
+    {
+        /* RFC 2144, Appendix B.1 */
+        .path = "/crypto/cipher/cast5-128",
+        .alg = QCRYPTO_CIPHER_ALG_CAST5_128,
+        .mode = QCRYPTO_CIPHER_MODE_ECB,
+        .key = "0123456712345678234567893456789A",
+        .plaintext = "0123456789abcdef",
+        .ciphertext = "238b4fe5847e44b2",
+    },
 };
 
 
-- 
2.5.0