Add single-DES support in SSH2

[u/mdw/putty] / ssh.c

diff --git a/ssh.c b/ssh.c
index 9b16d83..3a02b12 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -236,15 +236,13 @@ extern void pfd_override_throttle(Socket s, int enable);
 #define OUR_V2_WINSIZE 16384
 
 /*
- * Ciphers for SSH2. We miss out single-DES because it isn't
- * supported; also 3DES and Blowfish are both done differently from
- * SSH1. (3DES uses outer chaining; Blowfish has the opposite
- * endianness and different-sized keys.)
+ * Ciphers for SSH2.
  */
 const static struct ssh2_ciphers *ciphers[] = {
     &ssh2_aes,
     &ssh2_blowfish,
     &ssh2_3des,
+    &ssh2_des,
 };
 
 const static struct ssh_kex *kex_algs[] = {
@@ -3172,7 +3170,8 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
            n_preferred_ciphers++;
            break;
          case CIPHER_DES:
-           /* Not supported in SSH2; silently drop */
+           preferred_ciphers[n_preferred_ciphers] = &ssh2_des;
+           n_preferred_ciphers++;
            break;
          case CIPHER_3DES:
            preferred_ciphers[n_preferred_ciphers] = &ssh2_3des;
@@ -3353,6 +3352,11 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
            break;
        }
     }
+    if (!cscipher_tobe) {
+       bombout(("Couldn't agree a client-to-server cipher (available: %s)", str));
+       crReturn(0);
+    }
+
     ssh2_pkt_getstring(&str, &len);    /* server->client cipher */
     warn = 0;
     for (i = 0; i < n_preferred_ciphers; i++) {
@@ -3373,6 +3377,11 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
            break;
        }
     }
+    if (!sccipher_tobe) {
+       bombout(("Couldn't agree a server-to-client cipher (available: %s)", str));
+       crReturn(0);
+    }
+
     ssh2_pkt_getstring(&str, &len);    /* client->server mac */
     for (i = 0; i < nmacs; i++) {
        if (in_commasep_string(maclist[i]->name, str, len)) {
@@ -3500,15 +3509,6 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
     }
 
     /*
-     * Expect SSH2_MSG_NEWKEYS from server.
-     */
-    crWaitUntil(ispkt);
-    if (pktin.type != SSH2_MSG_NEWKEYS) {
-       bombout(("expected new-keys packet from server"));
-       crReturn(0);
-    }
-
-    /*
      * Authenticate remote host: verify host key. (We've already
      * checked the signature of the exchange hash.)
      */
@@ -3531,6 +3531,15 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
     ssh2_pkt_send();
 
     /*
+     * Expect SSH2_MSG_NEWKEYS from server.
+     */
+    crWaitUntil(ispkt);
+    if (pktin.type != SSH2_MSG_NEWKEYS) {
+       bombout(("expected new-keys packet from server"));
+       crReturn(0);
+    }
+
+    /*
      * Create and initialise session keys.
      */
     cscipher = cscipher_tobe;