- markus@cvs.openbsd.org 2003/05/17 04:27:52

[cipher.c cipher-ctr.c myproposal.h]
     experimental support for aes-ctr modes from
     http://www.ietf.org/internet-drafts/draft-ietf-secsh-newmodes-00.txt
     ok djm@

ChangeLog

@@ -9,6 +9,11 @@
    - itojun@cvs.openbsd.org 2003/05/17 03:25:58
      [auth-rhosts.c]
      just in case, put numbers to sscanf %s arg.
+   - markus@cvs.openbsd.org 2003/05/17 04:27:52
+     [cipher.c cipher-ctr.c myproposal.h]
+     experimental support for aes-ctr modes from
+     http://www.ietf.org/internet-drafts/draft-ietf-secsh-newmodes-00.txt
+     ok djm@
  - (djm) Remove IPv4 by default hack now that we can specify AF in config
 
 20030517
@@ -1565,4 +1570,4 @@
      save auth method before monitor_reset_key_state(); bugzilla bug #284;
      ok provos@
 
-$Id: ChangeLog,v 1.2735 2003/05/18 10:53:10 djm Exp $
+$Id: ChangeLog,v 1.2736 2003/05/18 10:53:59 djm Exp $

Makefile.in

@@ -1,4 +1,4 @@
-# $Id: Makefile.in,v 1.236 2003/05/15 11:33:46 djm Exp $
+# $Id: Makefile.in,v 1.237 2003/05/18 10:53:59 djm Exp $
 
 # uncomment if you run a non bourne compatable shell. Ie. csh
 #SHELL = @SH@
@@ -61,7 +61,7 @@ INSTALL_SSH_RAND_HELPER=@INSTALL_SSH_RAND_HELPER@
 TARGETS=ssh$(EXEEXT) sshd$(EXEEXT) ssh-add$(EXEEXT) ssh-keygen$(EXEEXT) ssh-keyscan${EXEEXT} ssh-keysign${EXEEXT} ssh-agent$(EXEEXT) scp$(EXEEXT) ssh-rand-helper${EXEEXT} sftp-server$(EXEEXT) sftp$(EXEEXT)
 
 LIBSSH_OBJS=authfd.o authfile.o bufaux.o buffer.o canohost.o channels.o \
-	cipher.o  cipher-aes.o cipher-bf1.o cipher-3des1.o \
+	cipher.o  cipher-aes.o cipher-bf1.o cipher-ctr.o cipher-3des1.o \
 	compat.o compress.o crc32.o deattack.o fatal.o \
 	hostfile.o log.o match.o mpaux.o nchan.o packet.o radix.o \
 	readpass.o rsa.o tildexpand.o ttymodes.o xmalloc.o atomicio.o \

cipher-ctr.c

@@ -0,0 +1,149 @@
+/*
+ * Copyright (c) 2003 Markus Friedl.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "includes.h"
+RCSID("$OpenBSD: cipher-ctr.c,v 1.1 2003/05/17 04:27:52 markus Exp $");
+
+#include <openssl/evp.h>
+
+#include "log.h"
+#include "xmalloc.h"
+
+#if OPENSSL_VERSION_NUMBER < 0x00907000L
+#include "rijndael.h"
+#define AES_KEY rijndael_ctx
+#define AES_BLOCK_SIZE 16
+#define AES_encrypt(a, b, c) rijndael_encrypt(c, a, b)
+#define AES_set_encrypt_key(a, b, c) rijndael_set_key(c, (char *)a, b, 1)
+#else
+#include <openssl/aes.h>
+#endif
+
+const EVP_CIPHER *evp_aes_128_ctr(void);
+void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
+
+struct ssh_aes_ctr_ctx
+{
+	AES_KEY		aes_ctx;
+	u_char		aes_counter[AES_BLOCK_SIZE];
+};
+
+/*
+ * increment counter 'ctr',
+ * the counter is of size 'len' bytes and stored in network-byte-order.
+ * (LSB at ctr[len-1], MSB at ctr[0])
+ */
+static void
+ssh_ctr_inc(u_char *ctr, u_int len)
+{
+	int i;
+
+	for (i = len - 1; i >= 0; i--)
+		if (++ctr[i])	/* continue on overflow */
+			return;
+}
+
+static int
+ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
+    u_int len)
+{
+	struct ssh_aes_ctr_ctx *c;
+	u_int n = 0;
+	u_char buf[AES_BLOCK_SIZE];
+
+	if (len == 0)
+		return (1);
+	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
+		return (0);
+
+	while ((len--) > 0) {
+		if (n == 0) {
+			AES_encrypt(c->aes_counter, buf, &c->aes_ctx);
+			ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE);
+		}
+		*(dest++) = *(src++) ^ buf[n];
+		n = (n + 1) % AES_BLOCK_SIZE;
+	}
+	return (1);
+}
+
+static int
+ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
+    int enc)
+{
+	struct ssh_aes_ctr_ctx *c;
+
+	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
+		c = xmalloc(sizeof(*c));
+		EVP_CIPHER_CTX_set_app_data(ctx, c);
+	}
+	if (key != NULL)
+                AES_set_encrypt_key(key, ctx->key_len * 8, &c->aes_ctx);
+	if (iv != NULL)
+		memcpy(c->aes_counter, iv, AES_BLOCK_SIZE);
+	return (1);
+}
+
+static int
+ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx)
+{
+	struct ssh_aes_ctr_ctx *c;
+
+	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
+		memset(c, 0, sizeof(*c));
+		xfree(c);
+		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
+	}
+	return (1);
+}
+
+void
+ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len)
+{
+	struct ssh_aes_ctr_ctx *c;
+
+	if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
+		fatal("ssh_aes_ctr_iv: no context");
+	if (doset)
+		memcpy(c->aes_counter, iv, len);
+	else
+		memcpy(iv, c->aes_counter, len);
+}
+
+const EVP_CIPHER *
+evp_aes_128_ctr(void)
+{
+	static EVP_CIPHER aes_ctr;
+
+	memset(&aes_ctr, 0, sizeof(EVP_CIPHER));
+	aes_ctr.nid = NID_undef;
+	aes_ctr.block_size = AES_BLOCK_SIZE;
+	aes_ctr.iv_len = AES_BLOCK_SIZE;
+	aes_ctr.key_len = 16;
+	aes_ctr.init = ssh_aes_ctr_init;
+	aes_ctr.cleanup = ssh_aes_ctr_cleanup;
+	aes_ctr.do_cipher = ssh_aes_ctr;
+	aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
+	    EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;
+	return (&aes_ctr);
+}

cipher.c

@@ -35,7 +35,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: cipher.c,v 1.64 2003/05/15 03:08:29 markus Exp $");
+RCSID("$OpenBSD: cipher.c,v 1.65 2003/05/17 04:27:52 markus Exp $");
 
 #include "xmalloc.h"
 #include "log.h"
@@ -55,6 +55,8 @@ extern void ssh_rijndael_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
 extern const EVP_CIPHER *evp_ssh1_bf(void);
 extern const EVP_CIPHER *evp_ssh1_3des(void);
 extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
+extern const EVP_CIPHER *evp_aes_128_ctr(void);
+extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
 
 struct Cipher {
 	char	*name;
@@ -85,6 +87,9 @@ struct Cipher {
 	{ "rijndael-cbc@lysator.liu.se",
 				SSH_CIPHER_SSH2, 16, 32, EVP_aes_256_cbc },
 #endif
+	{ "aes128-ctr", 	SSH_CIPHER_SSH2, 16, 16, evp_aes_128_ctr },
+	{ "aes192-ctr", 	SSH_CIPHER_SSH2, 16, 24, evp_aes_128_ctr },
+	{ "aes256-ctr", 	SSH_CIPHER_SSH2, 16, 32, evp_aes_128_ctr },
 
 	{ NULL,			SSH_CIPHER_ILLEGAL, 0, 0, NULL }
 };
@@ -337,6 +342,9 @@ cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
 			ssh_rijndael_iv(&cc->evp, 0, iv, len);
 		else
 #endif
+		if (c->evptype == evp_aes_128_ctr)
+			ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
+		else
 			memcpy(iv, cc->evp.iv, len);
 		break;
 	case SSH_CIPHER_3DES:
@@ -365,6 +373,9 @@ cipher_set_keyiv(CipherContext *cc, u_char *iv)
 			ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
 		else
 #endif
+		if (c->evptype == evp_aes_128_ctr)
+			ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
+		else
 			memcpy(cc->evp.iv, iv, evplen);
 		break;
 	case SSH_CIPHER_3DES:

myproposal.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: myproposal.h,v 1.14 2002/04/03 09:26:11 markus Exp $	*/
+/*	$OpenBSD: myproposal.h,v 1.15 2003/05/17 04:27:52 markus Exp $	*/
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -27,7 +27,8 @@
 #define	KEX_DEFAULT_PK_ALG	"ssh-rsa,ssh-dss"
 #define	KEX_DEFAULT_ENCRYPT \
 	"aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour," \
-	"aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se"
+	"aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se," \
+	"aes128-ctr,aes192-ctr,aes256-ctr"
 #define	KEX_DEFAULT_MAC \
 	"hmac-md5,hmac-sha1,hmac-ripemd160," \
 	"hmac-ripemd160@openssh.com," \