* added key derivation functions

1 files changed, 105 insertions, 0 deletions

diff --git a/keyDerivation.cpp b/keyDerivation.cpp
new file mode 100644
index 0000000..5663ac1
--- /dev/null
+++ b/keyDerivation.cpp
@@ -0,0 +1,105 @@
+/*
+ *  anytun
+ *
+ *  The secure anycast tunneling protocol (satp) defines a protocol used
+ *  for communication between any combination of unicast and anycast
+ *  tunnel endpoints.  It has less protocol overhead than IPSec in Tunnel
+ *  mode and allows tunneling of every ETHER TYPE protocol (e.g.
+ *  ethernet, ip, arp ...). satp directly includes cryptography and
+ *  message authentication based on the methodes used by SRTP.  It is
+ *  intended to deliver a generic, scaleable and secure solution for
+ *  tunneling and relaying of packets of any protocol.
+ *
+ *
+ *  Copyright (C) 2007 anytun.org <satp@wirdorange.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  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 (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+
+#include "keyDerivation.h"
+
+extern "C" {
+#include <srtp/crypto_kernel.h>
+}
+
+err_status_t KeyDerivation::init(const uint8_t key[30], const uint8_t salt[14])
+{
+  aes_icm_context_init(&kdf_, key);
+
+  for(uint8_t i = 0; i < 14; i++)
+    salt_[i] = salt[i];
+
+  return err_status_ok;
+}
+
+err_status_t KeyDerivation::setLogKDRate(const uint8_t log_rate)
+{
+  if( log_rate < 49 )
+  {
+    ld_kdr_ = log_rate;
+    return err_status_ok;
+  }
+  return err_status_bad_param;
+}
+
+
+err_status_t KeyDerivation::generate(satp_prf_label label, seq_nr_t seq_nr, uint8_t *key, int length)
+{
+  v128_t iv, salt, key_id;
+  uint8_t r = 0;
+
+  v128_set_to_zero(&iv);
+  v128_set_to_zero(&salt);
+  v128_set_to_zero(&key_id);
+
+  // look at: http://tools.ietf.org/html/rfc3711#section-4.3
+  if( ld_kdr_ == -1 )    // means key_derivation_rate = 0
+    r = 0;
+  else
+    // FIXXME: kdr can be greater than 2^32 (= 2^48)
+    r = seq_nr / ( 0x01 << ld_kdr_ );
+
+  key_id.v32[0] = (label << 8);
+  key_id.v32[0] += r;
+
+  v128_copy_octet_string(&salt, salt_);
+  v128_xor(&iv, &salt, &key_id);
+
+  aes_icm_set_iv(&kdf_, &iv);
+
+  /* generate keystream output */
+  aes_icm_output(&kdf_, key, length);
+
+  return err_status_ok;
+}
+
+
+err_status_t KeyDerivation::clear() 
+{
+  /* zeroize aes context */
+
+  v128_set_to_zero(&kdf_.counter);
+  v128_set_to_zero(&kdf_.offset);
+  v128_set_to_zero(&kdf_.keystream_buffer);
+  for(uint8_t i = 0; i < 11; i++)
+  {
+    v128_set_to_zero(&kdf_.expanded_key[i]);
+  }
+  kdf_.bytes_in_buffer = 0;
+
+  return err_status_ok;
+}
+