Now that we've got at least some SDCTR modes working (and aes256-ctr is our

default preferred cipher), add code to inject SSH_MSG_IGNOREs to randomise
the IV when using CBC-mode ciphers.  Each cipher has a flag to indicate
whether it needs this workaround, and the SSH packet output maze has gained
some extra complexity to implement it.

[originally from svn r5659]

ssh.h

@@ -154,6 +154,8 @@ struct ssh2_cipher {
     char *name;
     int blksize;
     int keylen;
+    unsigned int flags;
+#define SSH_CIPHER_IS_CBC	1
     char *text_name;
 };