- markus@cvs.openbsd.org 2013/01/08 18:49:04

[PROTOCOL authfile.c cipher.c cipher.h kex.c kex.h monitor_wrap.c]
     [myproposal.h packet.c ssh_config.5 sshd_config.5]
     support AES-GCM as defined in RFC 5647 (but with simpler KEX handling)
     ok and feedback djm@

ChangeLog

@@ -32,6 +32,11 @@
      sftp-server.8: add argument name to -d
      sftp-server.c: add -d to usage()
      ok djm
+   - markus@cvs.openbsd.org 2013/01/08 18:49:04
+     [PROTOCOL authfile.c cipher.c cipher.h kex.c kex.h monitor_wrap.c]
+     [myproposal.h packet.c ssh_config.5 sshd_config.5]
+     support AES-GCM as defined in RFC 5647 (but with simpler KEX handling)
+     ok and feedback djm@
 
 20121217
  - (dtucker) [Makefile.in] Add some scaffolding so that the new regress

PROTOCOL

@@ -79,6 +79,18 @@ contains:
       byte[n1]  payload; n1 = packet_length - padding_length - 1
       byte[n2]  random padding; n2 = padding_length
 
+1.6 transport: AES-GCM
+
+OpenSSH supports the AES-GCM algorithm as specified in RFC 5647.
+Because of problems with the specification of the key exchange
+the behaviour of OpenSSH differs from the RFC as follows:
+
+AES-GCM is only negotiated as the cipher algorithms
+"aes128-gcm@openssh.com" or "aes256-gcm@openssh.com" and never as
+an MAC algorithm. Additionally, if AES-GCM is selected as the cipher
+the exchanged MAC algorithms are ignored and there doesn't have to be
+a matching MAC.
+
 2. Connection protocol changes
 
 2.1. connection: Channel write close extension "eow@openssh.com"
@@ -319,4 +331,4 @@ link(oldpath, newpath) and will respond with a SSH_FXP_STATUS message.
 This extension is advertised in the SSH_FXP_VERSION hello with version
 "1".
 
-$OpenBSD: PROTOCOL,v 1.19 2013/01/03 12:49:01 djm Exp $
+$OpenBSD: PROTOCOL,v 1.20 2013/01/08 18:49:04 markus Exp $

authfile.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: authfile.c,v 1.94 2012/12/11 22:31:18 markus Exp $ */
+/* $OpenBSD: authfile.c,v 1.95 2013/01/08 18:49:04 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -150,7 +150,7 @@ key_private_rsa1_to_blob(Key *key, Buffer *blob, const char *passphrase,
 	cipher_set_key_string(&ciphercontext, cipher, passphrase,
 	    CIPHER_ENCRYPT);
 	cipher_crypt(&ciphercontext, cp,
-	    buffer_ptr(&buffer), buffer_len(&buffer), 0);
+	    buffer_ptr(&buffer), buffer_len(&buffer), 0, 0);
 	cipher_cleanup(&ciphercontext);
 	memset(&ciphercontext, 0, sizeof(ciphercontext));
 
@@ -474,7 +474,7 @@ key_parse_private_rsa1(Buffer *blob, const char *passphrase, char **commentp)
 	cipher_set_key_string(&ciphercontext, cipher, passphrase,
 	    CIPHER_DECRYPT);
 	cipher_crypt(&ciphercontext, cp,
-	    buffer_ptr(&copy), buffer_len(&copy), 0);
+	    buffer_ptr(&copy), buffer_len(&copy), 0, 0);
 	cipher_cleanup(&ciphercontext);
 	memset(&ciphercontext, 0, sizeof(ciphercontext));
 	buffer_free(&copy);

cipher.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.c,v 1.84 2012/12/12 16:46:10 naddy Exp $ */
+/* $OpenBSD: cipher.c,v 1.85 2013/01/08 18:49:04 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -71,29 +71,38 @@ struct Cipher {
 	u_int	cbc_mode;
 	const EVP_CIPHER	*(*evptype)(void);
 } ciphers[] = {
-	{ "none",		SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null },
-	{ "des",		SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc },
-	{ "3des",		SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des },
-	{ "blowfish",		SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf },
-
-	{ "3des-cbc",		SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc },
-	{ "blowfish-cbc",	SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc },
-	{ "cast128-cbc",	SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc },
-	{ "arcfour",		SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 },
-	{ "arcfour128",		SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 },
-	{ "arcfour256",		SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 },
-	{ "aes128-cbc",		SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc },
-	{ "aes192-cbc",		SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc },
-	{ "aes256-cbc",		SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
-	{ "rijndael-cbc@lysator.liu.se",
-				SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc },
-	{ "aes128-ctr",		SSH_CIPHER_SSH2, 16, 16, 0, 0, EVP_aes_128_ctr },
-	{ "aes192-ctr",		SSH_CIPHER_SSH2, 16, 24, 0, 0, EVP_aes_192_ctr },
-	{ "aes256-ctr",		SSH_CIPHER_SSH2, 16, 32, 0, 0, EVP_aes_256_ctr },
-#ifdef USE_CIPHER_ACSS
-	{ "acss@openssh.org",	SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss },
-#endif
 	{ NULL,			SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL }
+
+	{ "none",	SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
+	{ "des",	SSH_CIPHER_DES, 8, 8, 0, 0, 0, 1, EVP_des_cbc },
+	{ "3des",	SSH_CIPHER_3DES, 8, 16, 0, 0, 0, 1, evp_ssh1_3des },
+	{ "blowfish",	SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf },
+
+	{ "3des-cbc",	SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc },
+	{ "blowfish-cbc",
+			SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc },
+	{ "cast128-cbc",
+			SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc },
+	{ "arcfour",	SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 0, EVP_rc4 },
+	{ "arcfour128",	SSH_CIPHER_SSH2, 8, 16, 0, 0, 1536, 0, EVP_rc4 },
+	{ "arcfour256",	SSH_CIPHER_SSH2, 8, 32, 0, 0, 1536, 0, EVP_rc4 },
+	{ "aes128-cbc",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc },
+	{ "aes192-cbc",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc },
+	{ "aes256-cbc",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
+	{ "rijndael-cbc@lysator.liu.se",
+			SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
+	{ "aes128-ctr",	SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr },
+	{ "aes192-ctr",	SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr },
+	{ "aes256-ctr",	SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr },
+	{ "aes128-gcm@openssh.com",
+			SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm },
+	{ "aes256-gcm@openssh.com",
+			SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
+#ifdef USE_CIPHER_ACSS
+	{ "acss@openssh.org",
+			SSH_CIPHER_SSH2, 16, 5, 0, 0, 0, 0, EVP_acss },
+#endif
+	{ NULL,		SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
 };
 
 /*--*/
@@ -110,6 +119,18 @@ cipher_keylen(const Cipher *c)
 	return (c->key_len);
 }
 
+u_int
+cipher_authlen(const Cipher *c)
+{
+	return (c->auth_len);
+}
+
+u_int
+cipher_ivlen(const Cipher *c)
+{
+	return (c->iv_len ? c->iv_len : c->block_size);
+}
+
 u_int
 cipher_get_number(const Cipher *c)
 {
@@ -229,11 +250,12 @@ cipher_init(CipherContext *cc, Cipher *cipher,
 			keylen = 8;
 	}
 	cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
+	cc->encrypt = do_encrypt;
 
 	if (keylen < cipher->key_len)
 		fatal("cipher_init: key length %d is insufficient for %s.",
 		    keylen, cipher->name);
-	if (iv != NULL && ivlen < cipher->block_size)
+	if (iv != NULL && ivlen < cipher_ivlen(cipher))
 		fatal("cipher_init: iv length %d is insufficient for %s.",
 		    ivlen, cipher->name);
 	cc->cipher = cipher;
@@ -254,6 +276,11 @@ cipher_init(CipherContext *cc, Cipher *cipher,
 	    (do_encrypt == CIPHER_ENCRYPT)) == 0)
 		fatal("cipher_init: EVP_CipherInit failed for %s",
 		    cipher->name);
+	if (cipher_authlen(cipher) &&
+	    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
+	    -1, (u_char *)iv))
+		fatal("cipher_init: EVP_CTRL_GCM_SET_IV_FIXED failed for %s",
+		    cipher->name);
 	klen = EVP_CIPHER_CTX_key_length(&cc->evp);
 	if (klen > 0 && keylen != (u_int)klen) {
 		debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
@@ -284,19 +311,49 @@ cipher_init(CipherContext *cc, Cipher *cipher,
  * Theses bytes are treated as additional authenticated data for
  * authenticated encryption modes.
  * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
+ * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
+ * This tag is written on encryption and verified on decryption.
  * Both 'aadlen' and 'authlen' can be set to 0.
  */
 void
 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src,
-    u_int len, u_int aadlen)
+    u_int len, u_int aadlen, u_int authlen)
 {
-	if (aadlen)
+	if (authlen) {
+		u_char lastiv[1];
+
+		if (authlen != cipher_authlen(cc->cipher))
+			fatal("%s: authlen mismatch %d", __func__, authlen);
+		/* increment IV */
+		if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
+		    1, lastiv))
+			fatal("%s: EVP_CTRL_GCM_IV_GEN", __func__);
+		/* set tag on decyption */
+		if (!cc->encrypt &&
+		    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
+		    authlen, (u_char *)src + aadlen + len))
+			fatal("%s: EVP_CTRL_GCM_SET_TAG", __func__);
+	}
+	if (aadlen) {
+		if (authlen &&
+		    EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
+			fatal("%s: EVP_Cipher(aad) failed", __func__);
 		memcpy(dest, src, aadlen);
+	}
 	if (len % cc->cipher->block_size)
 		fatal("%s: bad plaintext length %d", __func__, len);
 	if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
 	    len) < 0)
 		fatal("%s: EVP_Cipher failed", __func__);
+	if (authlen) {
+		/* compute tag (on encrypt) or verify tag (on decrypt) */
+		if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0)
+			fatal("%s: EVP_Cipher(finish) failed", __func__);
+		if (cc->encrypt &&
+		    !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
+		    authlen, dest + aadlen + len))
+			fatal("%s: EVP_CTRL_GCM_GET_TAG", __func__);
+	}
 }
 
 void

cipher.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.h,v 1.38 2012/12/11 22:31:18 markus Exp $ */
+/* $OpenBSD: cipher.h,v 1.39 2013/01/08 18:49:04 markus Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -64,6 +64,7 @@ typedef struct CipherContext CipherContext;
 struct Cipher;
 struct CipherContext {
 	int	plaintext;
+	int	encrypt;
 	EVP_CIPHER_CTX evp;
 	Cipher *cipher;
 };
@@ -76,11 +77,14 @@ char	*cipher_name(int);
 int	 ciphers_valid(const char *);
 void	 cipher_init(CipherContext *, Cipher *, const u_char *, u_int,
     const u_char *, u_int, int);
-void	 cipher_crypt(CipherContext *, u_char *, const u_char *, u_int, u_int);
+void	 cipher_crypt(CipherContext *, u_char *, const u_char *,
+    u_int, u_int, u_int);
 void	 cipher_cleanup(CipherContext *);
 void	 cipher_set_key_string(CipherContext *, Cipher *, const char *, int);
 u_int	 cipher_blocksize(const Cipher *);
 u_int	 cipher_keylen(const Cipher *);
+u_int	 cipher_authlen(const Cipher *);
+u_int	 cipher_ivlen(const Cipher *);
 u_int	 cipher_is_cbc(const Cipher *);
 
 u_int	 cipher_get_number(const Cipher *);

kex.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.c,v 1.87 2012/08/17 01:22:56 djm Exp $ */
+/* $OpenBSD: kex.c,v 1.88 2013/01/08 18:49:04 markus Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  *
@@ -304,6 +304,7 @@ choose_enc(Enc *enc, char *client, char *server)
 	enc->name = name;
 	enc->enabled = 0;
 	enc->iv = NULL;
+	enc->iv_len = cipher_ivlen(enc->cipher);
 	enc->key = NULL;
 	enc->key_len = cipher_keylen(enc->cipher);
 	enc->block_size = cipher_blocksize(enc->cipher);
@@ -415,7 +416,7 @@ kex_choose_conf(Kex *kex)
 	char **my, **peer;
 	char **cprop, **sprop;
 	int nenc, nmac, ncomp;
-	u_int mode, ctos, need;
+	u_int mode, ctos, need, authlen;
 	int first_kex_follows, type;
 
 	my   = kex_buf2prop(&kex->my, NULL);
@@ -448,13 +449,16 @@ kex_choose_conf(Kex *kex)
 		nenc  = ctos ? PROPOSAL_ENC_ALGS_CTOS  : PROPOSAL_ENC_ALGS_STOC;
 		nmac  = ctos ? PROPOSAL_MAC_ALGS_CTOS  : PROPOSAL_MAC_ALGS_STOC;
 		ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
-		choose_enc (&newkeys->enc,  cprop[nenc],  sprop[nenc]);
+		choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]);
-		choose_mac (&newkeys->mac,  cprop[nmac],  sprop[nmac]);
+		/* ignore mac for authenticated encryption */
+		authlen = cipher_authlen(newkeys->enc.cipher);
+		if (authlen == 0)
+			choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]);
 		choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
 		debug("kex: %s %s %s %s",
 		    ctos ? "client->server" : "server->client",
 		    newkeys->enc.name,
-		    newkeys->mac.name,
+		    authlen == 0 ? newkeys->mac.name : "<implicit>",
 		    newkeys->comp.name);
 	}
 	choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
@@ -467,6 +471,8 @@ kex_choose_conf(Kex *kex)
 			need = newkeys->enc.key_len;
 		if (need < newkeys->enc.block_size)
 			need = newkeys->enc.block_size;
+		if (need < newkeys->enc.iv_len)
+			need = newkeys->enc.iv_len;
 		if (need < newkeys->mac.key_len)
 			need = newkeys->mac.key_len;
 	}

kex.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.h,v 1.53 2012/12/11 22:31:18 markus Exp $ */
+/* $OpenBSD: kex.h,v 1.54 2013/01/08 18:49:04 markus Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -89,6 +89,7 @@ struct Enc {
 	Cipher	*cipher;
 	int	enabled;
 	u_int	key_len;
+	u_int	iv_len;
 	u_int	block_size;
 	u_char	*key;
 	u_char	*iv;

monitor_wrap.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.c,v 1.74 2012/10/01 13:59:51 naddy Exp $ */
+/* $OpenBSD: monitor_wrap.c,v 1.75 2013/01/08 18:49:04 markus Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -491,16 +491,14 @@ mm_newkeys_from_blob(u_char *blob, int blen)
 	enc->enabled = buffer_get_int(&b);
 	enc->block_size = buffer_get_int(&b);
 	enc->key = buffer_get_string(&b, &enc->key_len);
-	enc->iv = buffer_get_string(&b, &len);
+	enc->iv = buffer_get_string(&b, &enc->iv_len);
-	if (len != enc->block_size)
-		fatal("%s: bad ivlen: expected %u != %u", __func__,
-		    enc->block_size, len);
 
 	if (enc->name == NULL || cipher_by_name(enc->name) != enc->cipher)
 		fatal("%s: bad cipher name %s or pointer %p", __func__,
 		    enc->name, enc->cipher);
 
 	/* Mac structure */
+	if (cipher_authlen(enc->cipher) == 0) {
 		mac->name = buffer_get_string(&b, NULL);
 		if (mac->name == NULL || mac_setup(mac, mac->name) == -1)
 			fatal("%s: can not setup mac %s", __func__, mac->name);
@@ -510,6 +508,7 @@ mm_newkeys_from_blob(u_char *blob, int blen)
 			fatal("%s: bad mac key length: %u > %d", __func__, len,
 			    mac->key_len);
 		mac->key_len = len;
+	}
 
 	/* Comp structure */
 	comp->type = buffer_get_int(&b);
@@ -551,13 +550,15 @@ mm_newkeys_to_blob(int mode, u_char **blobp, u_int *lenp)
 	buffer_put_int(&b, enc->enabled);
 	buffer_put_int(&b, enc->block_size);
 	buffer_put_string(&b, enc->key, enc->key_len);
-	packet_get_keyiv(mode, enc->iv, enc->block_size);
+	packet_get_keyiv(mode, enc->iv, enc->iv_len);
-	buffer_put_string(&b, enc->iv, enc->block_size);
+	buffer_put_string(&b, enc->iv, enc->iv_len);
 
 	/* Mac structure */
+	if (cipher_authlen(enc->cipher) == 0) {
 		buffer_put_cstring(&b, mac->name);
 		buffer_put_int(&b, mac->enabled);
 		buffer_put_string(&b, mac->key, mac->key_len);
+	}
 
 	/* Comp structure */
 	buffer_put_int(&b, comp->type);

myproposal.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: myproposal.h,v 1.31 2012/12/11 22:31:18 markus Exp $ */
+/* $OpenBSD: myproposal.h,v 1.32 2013/01/08 18:49:04 markus Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -73,6 +73,7 @@
 #define	KEX_DEFAULT_ENCRYPT \
 	"aes128-ctr,aes192-ctr,aes256-ctr," \
 	"arcfour256,arcfour128," \
+	"aes128-gcm@openssh.com,aes256-gcm@openssh.com," \
 	"aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc," \
 	"aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se"
 #ifdef HAVE_EVP_SHA256

packet.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.179 2012/12/12 16:45:52 markus Exp $ */
+/* $OpenBSD: packet.c,v 1.180 2013/01/08 18:49:04 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -709,7 +709,7 @@ packet_send1(void)
 	    buffer_len(&active_state->outgoing_packet));
 	cipher_crypt(&active_state->send_context, cp,
 	    buffer_ptr(&active_state->outgoing_packet),
-	    buffer_len(&active_state->outgoing_packet), 0);
+	    buffer_len(&active_state->outgoing_packet), 0, 0);
 
 #ifdef PACKET_DEBUG
 	fprintf(stderr, "encrypted: ");
@@ -757,7 +757,7 @@ set_newkeys(int mode)
 		mac  = &active_state->newkeys[mode]->mac;
 		comp = &active_state->newkeys[mode]->comp;
 		mac_clear(mac);
-		memset(enc->iv,  0, enc->block_size);
+		memset(enc->iv,  0, enc->iv_len);
 		memset(enc->key, 0, enc->key_len);
 		memset(mac->key, 0, mac->key_len);
 		xfree(enc->name);
@@ -774,11 +774,11 @@ set_newkeys(int mode)
 	enc  = &active_state->newkeys[mode]->enc;
 	mac  = &active_state->newkeys[mode]->mac;
 	comp = &active_state->newkeys[mode]->comp;
-	if (mac_init(mac) == 0)
+	if (cipher_authlen(enc->cipher) == 0 && mac_init(mac) == 0)
 		mac->enabled = 1;
 	DBG(debug("cipher_init_context: %d", mode));
 	cipher_init(cc, enc->cipher, enc->key, enc->key_len,
-	    enc->iv, enc->block_size, crypt_type);
+	    enc->iv, enc->iv_len, crypt_type);
 	/* Deleting the keys does not gain extra security */
 	/* memset(enc->iv,  0, enc->block_size);
 	   memset(enc->key, 0, enc->key_len);
@@ -846,7 +846,7 @@ packet_send2_wrapped(void)
 {
 	u_char type, *cp, *macbuf = NULL;
 	u_char padlen, pad = 0;
-	u_int i, len, aadlen = 0;
+	u_int i, len, authlen = 0, aadlen = 0;
 	u_int32_t rnd = 0;
 	Enc *enc   = NULL;
 	Mac *mac   = NULL;
@@ -857,9 +857,12 @@ packet_send2_wrapped(void)
 		enc  = &active_state->newkeys[MODE_OUT]->enc;
 		mac  = &active_state->newkeys[MODE_OUT]->mac;
 		comp = &active_state->newkeys[MODE_OUT]->comp;
+		/* disable mac for authenticated encryption */
+		if ((authlen = cipher_authlen(enc->cipher)) != 0)
+			mac = NULL;
 	}
 	block_size = enc ? enc->block_size : 8;
-	aadlen = mac && mac->enabled && mac->etm ? 4 : 0;
+	aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0;
 
 	cp = buffer_ptr(&active_state->outgoing_packet);
 	type = cp[5];
@@ -936,10 +939,10 @@ packet_send2_wrapped(void)
 		DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
 	}
 	/* encrypt packet and append to output buffer. */
-	cp = buffer_append_space(&active_state->output, len);
+	cp = buffer_append_space(&active_state->output, len + authlen);
 	cipher_crypt(&active_state->send_context, cp,
 	    buffer_ptr(&active_state->outgoing_packet),
-	    len - aadlen, aadlen);
+	    len - aadlen, aadlen, authlen);
 	/* append unencrypted MAC */
 	if (mac && mac->enabled) {
 		if (mac->etm) {
@@ -1199,7 +1202,7 @@ packet_read_poll1(void)
 	buffer_clear(&active_state->incoming_packet);
 	cp = buffer_append_space(&active_state->incoming_packet, padded_len);
 	cipher_crypt(&active_state->receive_context, cp,
-	    buffer_ptr(&active_state->input), padded_len, 0);
+	    buffer_ptr(&active_state->input), padded_len, 0, 0);
 
 	buffer_consume(&active_state->input, padded_len);
 
@@ -1248,7 +1251,7 @@ packet_read_poll2(u_int32_t *seqnr_p)
 {
 	u_int padlen, need;
 	u_char *macbuf = NULL, *cp, type;
-	u_int maclen, aadlen = 0, block_size;
+	u_int maclen, authlen = 0, aadlen = 0, block_size;
 	Enc *enc   = NULL;
 	Mac *mac   = NULL;
 	Comp *comp = NULL;
@@ -1260,10 +1263,13 @@ packet_read_poll2(u_int32_t *seqnr_p)
 		enc  = &active_state->newkeys[MODE_IN]->enc;
 		mac  = &active_state->newkeys[MODE_IN]->mac;
 		comp = &active_state->newkeys[MODE_IN]->comp;
+		/* disable mac for authenticated encryption */
+		if ((authlen = cipher_authlen(enc->cipher)) != 0)
+			mac = NULL;
 	}
 	maclen = mac && mac->enabled ? mac->mac_len : 0;
 	block_size = enc ? enc->block_size : 8;
-	aadlen = mac && mac->enabled && mac->etm ? 4 : 0;
+	aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0;
 
 	if (aadlen && active_state->packlen == 0) {
 		if (buffer_len(&active_state->input) < 4)
@@ -1290,7 +1296,7 @@ packet_read_poll2(u_int32_t *seqnr_p)
 		cp = buffer_append_space(&active_state->incoming_packet,
 		    block_size);
 		cipher_crypt(&active_state->receive_context, cp,
-		    buffer_ptr(&active_state->input), block_size, 0);
+		    buffer_ptr(&active_state->input), block_size, 0, 0);
 		cp = buffer_ptr(&active_state->incoming_packet);
 		active_state->packlen = get_u32(cp);
 		if (active_state->packlen < 1 + 4 ||
@@ -1316,8 +1322,8 @@ packet_read_poll2(u_int32_t *seqnr_p)
 		 */
 		need = 4 + active_state->packlen - block_size;
 	}
-	DBG(debug("partial packet: block %d, need %d, maclen %d, aadlen %d",
+	DBG(debug("partial packet: block %d, need %d, maclen %d, authlen %d,"
-	    block_size, need, maclen, aadlen));
+	    " aadlen %d", block_size, need, maclen, authlen, aadlen));
 	if (need % block_size != 0) {
 		logit("padding error: need %d block %d mod %d",
 		    need, block_size, need % block_size);
@@ -1329,10 +1335,11 @@ packet_read_poll2(u_int32_t *seqnr_p)
 	 * check if the entire packet has been received and
 	 * decrypt into incoming_packet:
 	 * 'aadlen' bytes are unencrypted, but authenticated.
-	 * 'need' bytes are encrypted, followed by
+	 * 'need' bytes are encrypted, followed by either
+	 * 'authlen' bytes of authentication tag or
 	 * 'maclen' bytes of message authentication code.
 	 */
-	if (buffer_len(&active_state->input) < aadlen + need + maclen)
+	if (buffer_len(&active_state->input) < aadlen + need + authlen + maclen)
 		return SSH_MSG_NONE;
 #ifdef PACKET_DEBUG
 	fprintf(stderr, "read_poll enc/full: ");
@@ -1344,8 +1351,8 @@ packet_read_poll2(u_int32_t *seqnr_p)
 		    buffer_ptr(&active_state->input), aadlen + need);
 	cp = buffer_append_space(&active_state->incoming_packet, aadlen + need);
 	cipher_crypt(&active_state->receive_context, cp,
-	    buffer_ptr(&active_state->input), need, aadlen);
+	    buffer_ptr(&active_state->input), need, aadlen, authlen);
-	buffer_consume(&active_state->input, aadlen + need);
+	buffer_consume(&active_state->input, aadlen + need + authlen);
 	/*
 	 * compute MAC over seqnr and packet,
 	 * increment sequence number for incoming packet

ssh_config.5

@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: ssh_config.5,v 1.160 2012/12/11 22:31:18 markus Exp $
+.\" $OpenBSD: ssh_config.5,v 1.161 2013/01/08 18:49:04 markus Exp $
-.Dd $Mdocdate: December 11 2012 $
+.Dd $Mdocdate: January 8 2013 $
 .Dt SSH_CONFIG 5
 .Os
 .Sh NAME
@@ -204,6 +204,8 @@ The supported ciphers are
 .Dq aes128-ctr ,
 .Dq aes192-ctr ,
 .Dq aes256-ctr ,
+.Dq aes128-gcm@openssh.com ,
+.Dq aes256-gcm@openssh.com ,
 .Dq arcfour128 ,
 .Dq arcfour256 ,
 .Dq arcfour ,
@@ -213,6 +215,7 @@ and
 The default is:
 .Bd -literal -offset 3n
 aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
+aes128-gcm@openssh.com,aes256-gcm@openssh.com,
 aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
 aes256-cbc,arcfour
 .Ed

sshd_config.5

@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd_config.5,v 1.152 2012/12/11 22:31:18 markus Exp $
+.\" $OpenBSD: sshd_config.5,v 1.153 2013/01/08 18:49:04 markus Exp $
-.Dd $Mdocdate: December 11 2012 $
+.Dd $Mdocdate: January 8 2013 $
 .Dt SSHD_CONFIG 5
 .Os
 .Sh NAME
@@ -336,6 +336,8 @@ The supported ciphers are
 .Dq aes128-ctr ,
 .Dq aes192-ctr ,
 .Dq aes256-ctr ,
+.Dq aes128-gcm@openssh.com ,
+.Dq aes256-gcm@openssh.com ,
 .Dq arcfour128 ,
 .Dq arcfour256 ,
 .Dq arcfour ,
@@ -345,6 +347,7 @@ and
 The default is:
 .Bd -literal -offset 3n
 aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
+aes128-gcm@openssh.com,aes256-gcm@openssh.com,
 aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
 aes256-cbc,arcfour
 .Ed