crypto: add support for the serpent cipher algorithm

New cipher algorithms 'serpent-128', 'serpent-192' and
'serpent-256' are defined for the Serpent algorithm.

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.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

crypto/cipher-gcrypt.c

@@ -30,6 +30,9 @@ bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
     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:
         return true;
     default:
         return false;
@@ -89,6 +92,18 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
         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;
+
     default:
         error_setg(errp, "Unsupported cipher algorithm %d", alg);
         return NULL;
@@ -122,6 +137,9 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm 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:
             ctx->blocksize = 16;
             break;
         case QCRYPTO_CIPHER_ALG_CAST5_128:

crypto/cipher-nettle.c

@@ -24,6 +24,7 @@
 #include <nettle/des.h>
 #include <nettle/cbc.h>
 #include <nettle/cast128.h>
+#include <nettle/serpent.h>
 
 #if CONFIG_NETTLE_VERSION_MAJOR < 3
 typedef nettle_crypt_func nettle_cipher_func;
@@ -76,6 +77,18 @@ static void cast128_decrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
     cast128_decrypt(ctx, length, dst, src);
 }
 
+static void serpent_encrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
+                                    uint8_t *dst, const uint8_t *src)
+{
+    serpent_encrypt(ctx, length, dst, src);
+}
+
+static void serpent_decrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
+                                    uint8_t *dst, const uint8_t *src)
+{
+    serpent_decrypt(ctx, length, dst, src);
+}
+
 typedef struct QCryptoCipherNettle QCryptoCipherNettle;
 struct QCryptoCipherNettle {
     void *ctx_encrypt;
@@ -94,6 +107,9 @@ bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
     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:
         return true;
     default:
         return false;
@@ -169,6 +185,21 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
 
         ctx->blocksize = CAST128_BLOCK_SIZE;
         break;
+
+    case QCRYPTO_CIPHER_ALG_SERPENT_128:
+    case QCRYPTO_CIPHER_ALG_SERPENT_192:
+    case QCRYPTO_CIPHER_ALG_SERPENT_256:
+        ctx->ctx_encrypt = g_new0(struct serpent_ctx, 1);
+        ctx->ctx_decrypt = NULL; /* 1 ctx can do both */
+
+        serpent_set_key(ctx->ctx_encrypt, nkey, key);
+
+        ctx->alg_encrypt = serpent_encrypt_wrapper;
+        ctx->alg_decrypt = serpent_decrypt_wrapper;
+
+        ctx->blocksize = SERPENT_BLOCK_SIZE;
+        break;
+
     default:
         error_setg(errp, "Unsupported cipher algorithm %d", alg);
         goto error;

crypto/cipher.c

@@ -28,6 +28,9 @@ static size_t alg_key_len[QCRYPTO_CIPHER_ALG__MAX] = {
     [QCRYPTO_CIPHER_ALG_AES_256] = 32,
     [QCRYPTO_CIPHER_ALG_DES_RFB] = 8,
     [QCRYPTO_CIPHER_ALG_CAST5_128] = 16,
+    [QCRYPTO_CIPHER_ALG_SERPENT_128] = 16,
+    [QCRYPTO_CIPHER_ALG_SERPENT_192] = 24,
+    [QCRYPTO_CIPHER_ALG_SERPENT_256] = 32,
 };
 
 static size_t alg_block_len[QCRYPTO_CIPHER_ALG__MAX] = {
@@ -36,6 +39,9 @@ static size_t alg_block_len[QCRYPTO_CIPHER_ALG__MAX] = {
     [QCRYPTO_CIPHER_ALG_AES_256] = 16,
     [QCRYPTO_CIPHER_ALG_DES_RFB] = 8,
     [QCRYPTO_CIPHER_ALG_CAST5_128] = 8,
+    [QCRYPTO_CIPHER_ALG_SERPENT_128] = 16,
+    [QCRYPTO_CIPHER_ALG_SERPENT_192] = 16,
+    [QCRYPTO_CIPHER_ALG_SERPENT_256] = 16,
 };
 
 static bool mode_need_iv[QCRYPTO_CIPHER_MODE__MAX] = {

qapi/crypto.json

@@ -60,13 +60,17 @@
 # @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
+# @serpent-128: Serpent with 128 bit / 16 byte keys
+# @serpent-192: Serpent with 192 bit / 24 byte keys
+# @serpent-256: Serpent with 256 bit / 32 byte keys
 # Since: 2.6
 ##
 { 'enum': 'QCryptoCipherAlgorithm',
   'prefix': 'QCRYPTO_CIPHER_ALG',
   'data': ['aes-128', 'aes-192', 'aes-256',
            'des-rfb',
-           'cast5-128']}
+           'cast5-128',
+           'serpent-128', 'serpent-192', 'serpent-256']}
 
 
 ##

tests/test-crypto-cipher.c

@@ -174,6 +174,45 @@ static QCryptoCipherTestData test_data[] = {
         .plaintext = "0123456789abcdef",
         .ciphertext = "238b4fe5847e44b2",
     },
+    {
+        /* libgcrypt serpent.c */
+        .path = "/crypto/cipher/serpent-128",
+        .alg = QCRYPTO_CIPHER_ALG_SERPENT_128,
+        .mode = QCRYPTO_CIPHER_MODE_ECB,
+        .key = "00000000000000000000000000000000",
+        .plaintext = "d29d576fcea3a3a7ed9099f29273d78e",
+        .ciphertext = "b2288b968ae8b08648d1ce9606fd992d",
+    },
+    {
+        /* libgcrypt serpent.c */
+        .path = "/crypto/cipher/serpent-192",
+        .alg = QCRYPTO_CIPHER_ALG_SERPENT_192,
+        .mode = QCRYPTO_CIPHER_MODE_ECB,
+        .key = "00000000000000000000000000000000"
+               "0000000000000000",
+        .plaintext = "d29d576fceaba3a7ed9899f2927bd78e",
+        .ciphertext = "130e353e1037c22405e8faefb2c3c3e9",
+    },
+    {
+        /* libgcrypt serpent.c */
+        .path = "/crypto/cipher/serpent-256a",
+        .alg = QCRYPTO_CIPHER_ALG_SERPENT_256,
+        .mode = QCRYPTO_CIPHER_MODE_ECB,
+        .key = "00000000000000000000000000000000"
+               "00000000000000000000000000000000",
+        .plaintext = "d095576fcea3e3a7ed98d9f29073d78e",
+        .ciphertext = "b90ee5862de69168f2bdd5125b45472b",
+    },
+    {
+        /* libgcrypt serpent.c */
+        .path = "/crypto/cipher/serpent-256b",
+        .alg = QCRYPTO_CIPHER_ALG_SERPENT_256,
+        .mode = QCRYPTO_CIPHER_MODE_ECB,
+        .key = "00000000000000000000000000000000"
+               "00000000000000000000000000000000",
+        .plaintext = "00000000010000000200000003000000",
+        .ciphertext = "2061a42782bd52ec691ec383b03ba77c",
+    },
 };