1 files changed, 11 insertions, 5 deletions

diff --git a/kex.c b/kex.c
index f77b3c925..57a79dd9e 100644
--- a/kex.c
+++ b/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_mac (&newkeys->mac,  cprop[nmac],  sprop[nmac]);
+                choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]);
+                /* 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;
         }