1 files changed, 94 insertions, 0 deletions
diff --git a/libotr-3.2.0/toolkit/sesskeys.c b/libotr-3.2.0/toolkit/sesskeys.c
new file mode 100644
index 0000000..d823ebc
--- /dev/null
+++ b/libotr-3.2.0/toolkit/sesskeys.c
@@ -0,0 +1,94 @@
+/*
+ *  Off-the-Record Messaging Toolkit
+ *  Copyright (C) 2004-2008  Ian Goldberg, Chris Alexander, Nikita Borisov
+ *                           <otr@cypherpunks.ca>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of version 2 of the GNU General Public License as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/* system headers */
+#include <stdlib.h>
+
+/* libgcrypt headers */
+#include <gcrypt.h>
+
+static const char* DH1536_MODULUS_S = "0x"
+    "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1"
+    "29024E088A67CC74020BBEA63B139B22514A08798E3404DD"
+    "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245"
+    "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED"
+    "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3D"
+    "C2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F"
+    "83655D23DCA3AD961C62F356208552BB9ED529077096966D"
+    "670C354E4ABC9804F1746C08CA237327FFFFFFFFFFFFFFFF";
+static const char *DH1536_GENERATOR_S = "0x02";
+
+/* Generate the session id and the two encryption keys from our private
+ * DH key and their public DH key.  Also indicate in *high_endp if we
+ * are the "high" end of the key exchange (set to 1) or the "low" end
+ * (set to 0) */
+void sesskeys_gen(unsigned char sessionid[20], unsigned char sendenc[16],
+	unsigned char rcvenc[16], int *high_endp, gcry_mpi_t *our_yp,
+	gcry_mpi_t our_x, gcry_mpi_t their_y)
+{
+    gcry_mpi_t modulus, generator, secretv;
+    unsigned char *secret;
+    size_t secretlen;
+    unsigned char hash[20];
+    int is_high;
+
+    gcry_mpi_scan(&modulus, GCRYMPI_FMT_HEX, DH1536_MODULUS_S, 0, NULL);
+    gcry_mpi_scan(&generator, GCRYMPI_FMT_HEX, DH1536_GENERATOR_S, 0, NULL);
+    *our_yp = gcry_mpi_new(0);
+    gcry_mpi_powm(*our_yp, generator, our_x, modulus);
+    secretv = gcry_mpi_new(0);
+    gcry_mpi_powm(secretv, their_y, our_x, modulus);
+    gcry_mpi_release(generator);
+    gcry_mpi_release(modulus);
+    gcry_mpi_print(GCRYMPI_FMT_USG, NULL, 0, &secretlen, secretv);
+    secret = malloc(secretlen + 5);
+
+    secret[1] = (secretlen >> 24) & 0xff;
+    secret[2] = (secretlen >> 16) & 0xff;
+    secret[3] = (secretlen >> 8) & 0xff;
+    secret[4] = (secretlen) & 0xff;
+    gcry_mpi_print(GCRYMPI_FMT_USG, secret+5, secretlen, NULL, secretv);
+    gcry_mpi_release(secretv);
+
+    is_high = (gcry_mpi_cmp(*our_yp, their_y) > 0);
+
+    /* Calculate the session id */
+    secret[0] = 0x00;
+    gcry_md_hash_buffer(GCRY_MD_SHA1, hash, secret, secretlen+5);
+    memmove(sessionid, hash, 20);
+
+    /* Calculate the sending enc key */
+    secret[0] = is_high ? 0x01 : 0x02;
+    gcry_md_hash_buffer(GCRY_MD_SHA1, hash, secret, secretlen+5);
+    memmove(sendenc, hash, 16);
+
+    /* Calculate the receiving enc key */
+    secret[0] = is_high ? 0x02 : 0x01;
+    gcry_md_hash_buffer(GCRY_MD_SHA1, hash, secret, secretlen+5);
+    memmove(rcvenc, hash, 16);
+
+    *high_endp = is_high;
+    free(secret);
+}
+
+/* Generate a MAC key from the corresponding encryption key */
+void sesskeys_make_mac(unsigned char mackey[20], unsigned char enckey[16])
+{
+    gcry_md_hash_buffer(GCRY_MD_SHA1, mackey, enckey, 16);
+}