Support AES-Counter ciphers.

COPYING

@@ -1,6 +1,7 @@
 /* Copyright (c) 2004-2007 Sara Golemon <sarag@libssh2.org>
  * Copyright (c) 2006-2007 The Written Word, Inc.
  * Copyright (c) 2009 Daniel Stenberg
+ * Copyright (C) 2008, 2009 Simon Josefsson
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms,

NEWS

@@ -7,6 +7,10 @@ Version 1.2.2 (unreleased)
     <http://thread.gmane.org/gmane.network.ssh.libssh2.devel/2530>.
     By Simon Josefsson.
 
+  o Support for the "aes128-ctr", "aes192-ctr", "aes256-ctr" ciphers
+    as per RFC 4344 for libgcrypt and OpenSSL.  They are now the
+    preferred ciphers.  By Simon Josefsson.
+
   o Support for the "arcfour128" cipher as per RFC 4345 for libgcrypt
     and OpenSSL.  It is preferred over the normal "arcfour" cipher
     which is somewhat broken.  By Simon Josefsson.

src/crypt.c

@@ -1,5 +1,5 @@
-/* Copyright (c) 2004-2007, Sara Golemon <sarag@libssh2.org>
+/* Copyright (c) 2009 Simon Josefsson <simon@josefsson.org>
- * Copyright (c) 2009 Simon Josefsson <simon@josefsson.org>
+ * Copyright (c) 2004-2007, Sara Golemon <sarag@libssh2.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms,
@@ -115,6 +115,44 @@ crypt_dtor(LIBSSH2_SESSION * session, void **abstract)
     return 0;
 }
 
+#if LIBSSH2_AES_CTR
+static const LIBSSH2_CRYPT_METHOD libssh2_crypt_method_aes128_ctr = {
+    "aes128-ctr",
+    16,                         /* blocksize */
+    16,                         /* initial value length */
+    16,                         /* secret length -- 16*8 == 128bit */
+    0,                          /* flags */
+    &crypt_init,
+    &crypt_encrypt,
+    &crypt_dtor,
+    _libssh2_cipher_aes128ctr
+};
+
+static const LIBSSH2_CRYPT_METHOD libssh2_crypt_method_aes192_ctr = {
+    "aes192-ctr",
+    16,                         /* blocksize */
+    16,                         /* initial value length */
+    24,                         /* secret length -- 24*8 == 192bit */
+    0,                          /* flags */
+    &crypt_init,
+    &crypt_encrypt,
+    &crypt_dtor,
+    _libssh2_cipher_aes192ctr
+};
+
+static const LIBSSH2_CRYPT_METHOD libssh2_crypt_method_aes256_ctr = {
+    "aes256-ctr",
+    16,                         /* blocksize */
+    16,                         /* initial value length */
+    32,                         /* secret length -- 32*8 == 256bit */
+    0,                          /* flags */
+    &crypt_init,
+    &crypt_encrypt,
+    &crypt_dtor,
+    _libssh2_cipher_aes256ctr
+};
+#endif
+
 #if LIBSSH2_AES
 static const LIBSSH2_CRYPT_METHOD libssh2_crypt_method_aes128_cbc = {
     "aes128-cbc",
@@ -258,6 +296,11 @@ static const LIBSSH2_CRYPT_METHOD libssh2_crypt_method_3des_cbc = {
 #endif
 
 static const LIBSSH2_CRYPT_METHOD *_libssh2_crypt_methods[] = {
+#if LIBSSH2_AES_CTR
+  &libssh2_crypt_method_aes128_ctr,
+  &libssh2_crypt_method_aes192_ctr,
+  &libssh2_crypt_method_aes256_ctr,
+#endif /* LIBSSH2_AES */
 #if LIBSSH2_AES
     &libssh2_crypt_method_aes256_cbc,
     &libssh2_crypt_method_rijndael_cbc_lysator_liu_se,  /* == aes256-cbc */

src/libgcrypt.c

@@ -544,6 +544,9 @@ _libssh2_cipher_init(_libssh2_cipher_ctx * h,
 
     if (mode != GCRY_CIPHER_MODE_STREAM) {
         int blklen = gcry_cipher_get_algo_blklen(cipher);
+	if (mode == GCRY_CIPHER_MODE_CTR)
+	  ret = gcry_cipher_setctr(*h, iv, blklen);
+	else
 	  ret = gcry_cipher_setiv(*h, iv, blklen);
 	if (ret) {
             gcry_cipher_close(*h);

src/libgcrypt.h

@@ -44,6 +44,7 @@
 #define LIBSSH2_HMAC_RIPEMD 1
 
 #define LIBSSH2_AES 1
+#define LIBSSH2_AES_CTR 1
 #define LIBSSH2_BLOWFISH 1
 #define LIBSSH2_RC4 1
 #define LIBSSH2_CAST 1
@@ -160,6 +161,12 @@ int _libssh2_dsa_sha1_sign(libssh2_dsa_ctx * dsactx,
 #define _libssh2_gcry_cipher(c) (c >> 8)
 #define _libssh2_gcry_mode(m) (m & 0xFF)
 
+#define _libssh2_cipher_aes256ctr		\
+  _libssh2_gcry_ciphermode(GCRY_CIPHER_AES256, GCRY_CIPHER_MODE_CTR)
+#define _libssh2_cipher_aes192ctr		\
+  _libssh2_gcry_ciphermode(GCRY_CIPHER_AES192, GCRY_CIPHER_MODE_CTR)
+#define _libssh2_cipher_aes128ctr					\
+  _libssh2_gcry_ciphermode(GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_CTR)
 #define _libssh2_cipher_aes256						\
   _libssh2_gcry_ciphermode(GCRY_CIPHER_AES256, GCRY_CIPHER_MODE_CBC)
 #define _libssh2_cipher_aes192			\

src/openssl.c

@@ -1,7 +1,9 @@
-/* Copyright (C) 2006, 2007 The Written Word, Inc.  All rights reserved.
+/* Copyright (C) 2009 Simon Josefsson
- * Author: Simon Josefsson
+ * Copyright (C) 2006, 2007 The Written Word, Inc.  All rights reserved.
  * Copyright (c) 2004-2006, Sara Golemon <sarag@libssh2.org>
  *
+ * Author: Simon Josefsson
+ *
  * Redistribution and use in source and binary forms,
  * with or without modification, are permitted provided
  * that the following conditions are met:
@@ -197,6 +199,106 @@ _libssh2_cipher_crypt(_libssh2_cipher_ctx * ctx,
     return ret == 1 ? 0 : 1;
 }
 
+#include <openssl/aes.h>
+
+typedef struct
+{
+    AES_KEY       key;
+    unsigned char ctr[AES_BLOCK_SIZE];
+} aes_ctr_ctx;
+
+static int
+aes_ctr_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
+	     const unsigned char *iv, int enc) /* init key */
+{
+    aes_ctr_ctx *c = malloc(sizeof(*c));
+    if (c == NULL)
+	return 0;
+
+    AES_set_encrypt_key(key, 8 * ctx->key_len, &c->key);
+    memcpy(c->ctr, iv, AES_BLOCK_SIZE);
+
+    EVP_CIPHER_CTX_set_app_data(ctx, c);
+
+    return 1;
+}
+
+static int
+aes_ctr_do_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
+		  const unsigned char *in,
+		  unsigned int inl) /* encrypt/decrypt data */
+{
+    aes_ctr_ctx *c = EVP_CIPHER_CTX_get_app_data(ctx);
+    unsigned char b1[AES_BLOCK_SIZE];
+    size_t i;
+
+    if (inl != 16) /* libssh2 only ever encrypt one block */
+	return 0;
+
+/*
+  To encrypt a packet P=P1||P2||...||Pn (where P1, P2, ..., Pn are each
+  blocks of length L), the encryptor first encrypts <X> with <cipher>
+  to obtain a block B1.  The block B1 is then XORed with P1 to generate
+  the ciphertext block C1.  The counter X is then incremented
+*/
+
+    AES_encrypt(c->ctr, b1, &c->key);
+
+    for (i = 0; i < 16; i++)
+	*out++ = *in++ ^ b1[i];
+
+    i = 15;
+    while (c->ctr[i]++ == 0xFF) {
+	if (i == 0)
+	    break;
+	i--;
+    }
+
+    return 1;
+}
+
+static int
+aes_ctr_cleanup(EVP_CIPHER_CTX *ctx) /* cleanup ctx */
+{
+    free(EVP_CIPHER_CTX_get_app_data(ctx));
+    return 1;
+}
+
+static const EVP_CIPHER *
+make_ctr_evp (size_t keylen)
+{
+    static EVP_CIPHER aes_ctr_cipher;
+
+    memset(&aes_ctr_cipher, 0, sizeof(aes_ctr_cipher));
+
+    aes_ctr_cipher.block_size = 16;
+    aes_ctr_cipher.key_len = keylen;
+    aes_ctr_cipher.iv_len = 16;
+    aes_ctr_cipher.init = aes_ctr_init;
+    aes_ctr_cipher.do_cipher = aes_ctr_do_cipher;
+    aes_ctr_cipher.cleanup = aes_ctr_cleanup;
+
+    return &aes_ctr_cipher;
+}
+
+const EVP_CIPHER *
+_libssh2_EVP_aes_128_ctr(void)
+{
+    return make_ctr_evp (16);
+}
+
+const EVP_CIPHER *
+_libssh2_EVP_aes_192_ctr(void)
+{
+    return make_ctr_evp (24);
+}
+
+const EVP_CIPHER *
+_libssh2_EVP_aes_256_ctr(void)
+{
+    return make_ctr_evp (32);
+}
+
 /* TODO: Optionally call a passphrase callback specified by the
  * calling program
  */

src/openssl.h

@@ -1,4 +1,6 @@
-/* Copyright (C) 2006, 2007 The Written Word, Inc.  All rights reserved.
+/* Copyright (C) 2009 Simon Josefsson
+ * Copyright (C) 2006, 2007 The Written Word, Inc.  All rights reserved.
+ *
  * Author: Simon Josefsson
  *
  * Redistribution and use in source and binary forms,
@@ -71,6 +73,7 @@
 #endif
 
 #if OPENSSL_VERSION_NUMBER >= 0x00907000L && !defined(OPENSSL_NO_AES)
+# define LIBSSH2_AES_CTR 1
 # define LIBSSH2_AES 1
 #else
 # define LIBSSH2_AES 0
@@ -194,6 +197,9 @@ int _libssh2_dsa_sha1_sign(libssh2_dsa_ctx * dsactx,
 #define _libssh2_cipher_aes256 EVP_aes_256_cbc
 #define _libssh2_cipher_aes192 EVP_aes_192_cbc
 #define _libssh2_cipher_aes128 EVP_aes_128_cbc
+#define _libssh2_cipher_aes128ctr _libssh2_EVP_aes_128_ctr
+#define _libssh2_cipher_aes192ctr _libssh2_EVP_aes_192_ctr
+#define _libssh2_cipher_aes256ctr _libssh2_EVP_aes_256_ctr
 #define _libssh2_cipher_blowfish EVP_bf_cbc
 #define _libssh2_cipher_arcfour EVP_rc4
 #define _libssh2_cipher_cast5 EVP_cast5_cbc
@@ -223,3 +229,7 @@ int _libssh2_cipher_crypt(_libssh2_cipher_ctx * ctx,
 #define _libssh2_bn_bytes(bn) BN_num_bytes(bn)
 #define _libssh2_bn_bits(bn) BN_num_bits(bn)
 #define _libssh2_bn_free(bn) BN_clear_free(bn)
+
+const EVP_CIPHER *_libssh2_EVP_aes_128_ctr(void);
+const EVP_CIPHER *_libssh2_EVP_aes_192_ctr(void);
+const EVP_CIPHER *_libssh2_EVP_aes_256_ctr(void);