--- a/algo.h	Mon Sep 29 02:23:04 2008 +0000
+++ b/algo.h	Mon Sep 29 13:53:31 2008 +0000
@@ -29,13 +29,18 @@
 #include "includes.h"
 #include "buffer.h"
 
+#define DROPBEAR_MODE_UNUSED 0
+#define DROPBEAR_MODE_CBC 1
+#define DROPBEAR_MODE_CTR 2
+
 struct Algo_Type {
 
 	unsigned char *name; /* identifying name */
 	char val; /* a value for this cipher, or -1 for invalid */
-	void *data; /* algorithm specific data */
-	unsigned usable : 1; /* whether we can use this algorithm */
-
+	const void *data; /* algorithm specific data */
+	char usable; /* whether we can use this algorithm */
+	const void *mode; /* the mode, currently only used for ciphers,
+						 points to a 'struct dropbear_cipher_mode' */
 };
 
 typedef struct Algo_Type algo_type;
@@ -48,6 +53,7 @@
 extern algo_type sshcompress[];
 
 extern const struct dropbear_cipher dropbear_nocipher;
+extern const struct dropbear_cipher_mode dropbear_mode_none;
 extern const struct dropbear_hash dropbear_nohash;
 
 struct dropbear_cipher {
@@ -56,6 +62,16 @@
 	unsigned char blocksize;
 };
 
+struct dropbear_cipher_mode {
+	int (*start)(int cipher, const unsigned char *IV, 
+			const unsigned char *key, 
+			int keylen, int num_rounds, void *cipher_state);
+	int (*encrypt)(const unsigned char *pt, unsigned char *ct, 
+			unsigned long len, void *cipher_state);
+	int (*decrypt)(const unsigned char *ct, unsigned char *pt, 
+			unsigned long len, void *cipher_state);
+};
+
 struct dropbear_hash {
 	const struct ltc_hash_descriptor *hashdesc;
 	unsigned long keysize;