SSH2 transport layer now enables encryption and MAC successfully for 3DES

[u/mdw/putty] / ssh.c

diff --git a/ssh.c b/ssh.c
index ae41a80..d327471 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -88,11 +88,12 @@ enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR };
 #define crWaitUntil(c) do { crReturn(0); } while (!(c))
 
 extern struct ssh_cipher ssh_3des;
+extern struct ssh_cipher ssh_3des_ssh2;
 extern struct ssh_cipher ssh_des;
 extern struct ssh_cipher ssh_blowfish;
 
 /* for ssh 2; we miss out single-DES because it isn't supported */
-struct ssh_cipher *ciphers[] = { &ssh_3des, &ssh_blowfish };
+struct ssh_cipher *ciphers[] = { &ssh_3des_ssh2, &ssh_blowfish };
 
 extern struct ssh_kex ssh_diffiehellman;
 struct ssh_kex *kex_algs[] = { &ssh_diffiehellman };
@@ -104,11 +105,11 @@ extern struct ssh_mac ssh_sha1;
 
 SHA_State exhash;
 
-static void nullmac_sesskey(unsigned char *key, int len) { }
+static void nullmac_key(unsigned char *key) { }
 static void nullmac_generate(unsigned char *blk, int len, unsigned long seq) { }
 static int nullmac_verify(unsigned char *blk, int len, unsigned long seq) { return 1; }
 struct ssh_mac ssh_mac_none = {
-    nullmac_sesskey, nullmac_generate, nullmac_verify, "none", 0
+    nullmac_key, nullmac_key, nullmac_generate, nullmac_verify, "none", 0
 };
 struct ssh_mac *macs[] = { &ssh_sha1, &ssh_mac_none };
 
@@ -346,8 +347,16 @@ next_packet:
         /* FIXME */
     }
 #endif
+    debug(("Got initblk:"));
+    for (i = 0; i < cipherblk; i++)
+        debug(("  %02x", (unsigned char)pktin.data[i]));
+    debug(("\r\n"));
     if (sccipher)
         sccipher->decrypt(pktin.data, cipherblk);
+    debug(("Decrypted initblk:"));
+    for (i = 0; i < cipherblk; i++)
+        debug(("  %02x", (unsigned char)pktin.data[i]));
+    debug(("\r\n"));
 
     /*
      * Now get the length and padding figures.
@@ -392,20 +401,20 @@ next_packet:
     if (sccipher)
         sccipher->decrypt(pktin.data + cipherblk, packetlen - cipherblk);
 
+    debug(("Got packet len=%d pad=%d\r\n", len, pad));
+    for (i = 0; i < packetlen; i++)
+        debug(("  %02x", (unsigned char)pktin.data[i]));
+    debug(("\r\n"));
+
     /*
      * Check the MAC.
      */
-    if (scmac && !scmac->verify(pktin.data, incoming_sequence++, len+4))
+    if (scmac && !scmac->verify(pktin.data, len+4, incoming_sequence))
        fatalbox("Incorrect MAC received on packet");
+    incoming_sequence++;               /* whether or not we MACed */
 
     pktin.savedpos = 6;
     pktin.type = pktin.data[5];
-#if 0
-    debug(("Got packet len=%d pad=%d\r\n", len, pad));
-    for (i = 0; i < payload; i++)
-        debug(("  %02x", (unsigned char)pktin.data[i]));
-    debug(("\r\n"));
-#endif
 
     /*
      * FIXME: handle IGNORE and DEBUG messages.
@@ -1200,7 +1209,7 @@ void ssh2_pkt_addmp(Bignum b) {
 }
 void ssh2_pkt_send(void) {
     int cipherblk, maclen, padding, i;
-    unsigned long outgoing_sequence = 0;
+    static unsigned long outgoing_sequence = 0;
 
     /*
      * Add padding. At least four bytes, and must also bring total
@@ -1215,8 +1224,9 @@ void ssh2_pkt_send(void) {
         pktout.data[pktout.length + i] = random_byte();
     PUT_32BIT(pktout.data, pktout.length + padding - 4);
     if (csmac)
-        csmac->generate(pktout.data, outgoing_sequence++,
-                      pktout.length + padding);
+        csmac->generate(pktout.data, pktout.length + padding,
+                        outgoing_sequence);
+    outgoing_sequence++;               /* whether or not we MACed */
     if (cscipher)
         cscipher->encrypt(pktout.data, pktout.length + padding);
     maclen = csmac ? csmac->len : 0;
@@ -1311,6 +1321,26 @@ int in_commasep_string(char *needle, char *haystack, int haylen) {
 }
 
 /*
+ * SSH2 key creation method.
+ */
+void ssh2_mkkey(Bignum K, char *H, char chr, char *keyspace) {
+    SHA_State s;
+    /* First 20 bytes. */
+    SHA_Init(&s);
+    sha_mpint(&s, K);
+    SHA_Bytes(&s, H, 20);
+    SHA_Bytes(&s, &chr, 1);
+    SHA_Bytes(&s, H, 20);
+    SHA_Final(&s, keyspace);
+    /* Next 20 bytes. */
+    SHA_Init(&s);
+    sha_mpint(&s, K);
+    SHA_Bytes(&s, H, 20);
+    SHA_Bytes(&s, keyspace, 20);
+    SHA_Final(&s, keyspace+20);
+}
+
+/*
  * Handle the SSH2 key exchange phase.
  */
 static int do_ssh2_kex(unsigned char *in, int inlen, int ispkt)
@@ -1327,6 +1357,7 @@ static int do_ssh2_kex(unsigned char *in, int inlen, int ispkt)
     static char *hostkeydata, *sigdata;
     static int hostkeylen, siglen;
     static unsigned char exchange_hash[20];
+    static unsigned char keyspace[40];
 
     crBegin;
 
@@ -1519,9 +1550,51 @@ static int do_ssh2_kex(unsigned char *in, int inlen, int ispkt)
     debug(("\r\n"));
 
     /*
-     * FIXME: verify hostkeydata and sigdata.
+     * FIXME: verify host key. This bit will be moderately
+     * unpleasant, because of having to rewrite it to work
+     * alongside the old scheme.
      */
-    
+
+    /*
+     * FIXME: verify signature of exchange hash.
+     */
+
+    /*
+     * Send SSH2_MSG_NEWKEYS. Expect it from server.
+     */
+    ssh2_pkt_init(SSH2_MSG_NEWKEYS);
+    ssh2_pkt_send();
+    crWaitUntil(ispkt);
+    if (pktin.type != SSH2_MSG_NEWKEYS)
+        fatalbox("expected new-keys packet from server");
+
+    /*
+     * Create and initialise session keys.
+     */
+    cscipher = cscipher_tobe;
+    sccipher = sccipher_tobe;
+    csmac = csmac_tobe;
+    scmac = scmac_tobe;
+    cscomp = cscomp_tobe;
+    sccomp = sccomp_tobe;
+    /*
+     * Set IVs after keys.
+     */
+    ssh2_mkkey(K, exchange_hash, 'C', keyspace); cscipher->setcskey(keyspace);
+    ssh2_mkkey(K, exchange_hash, 'D', keyspace); cscipher->setsckey(keyspace);
+    ssh2_mkkey(K, exchange_hash, 'A', keyspace); cscipher->setcsiv(keyspace);
+    ssh2_mkkey(K, exchange_hash, 'B', keyspace); sccipher->setsciv(keyspace);
+    ssh2_mkkey(K, exchange_hash, 'E', keyspace); csmac->setcskey(keyspace);
+    ssh2_mkkey(K, exchange_hash, 'F', keyspace); scmac->setsckey(keyspace);
+
+    /*
+     * Now we're encrypting. Send a test packet (FIXME).
+     */
+    crWaitUntil(!ispkt);
+    ssh2_pkt_init(SSH2_MSG_IGNORE);
+    ssh2_pkt_addstring("oo-er");
+    ssh2_pkt_send();
+
     crWaitUntil(0);
 
     crFinish(1);