Outline of RFC 5077 session tickets

1 files changed, 91 insertions, 1 deletions

diff --git a/src/tls/tls_session.cpp b/src/tls/tls_session.cpp
index deaddb227..c40e9d79e 100644
--- a/src/tls/tls_session.cpp
+++ b/src/tls/tls_session.cpp
@@ -1,6 +1,6 @@
 /*
 * TLS Session State
-* (C) 2011 Jack Lloyd
+* (C) 2011-2012 Jack Lloyd
 *
 * Released under the terms of the Botan license
 */
@@ -10,6 +10,8 @@
 #include <botan/ber_dec.h>
 #include <botan/asn1_str.h>
 #include <botan/time.h>
+#include <botan/lookup.h>
+#include <memory>
 
 namespace Botan {
 
@@ -91,4 +93,92 @@ SecureVector<byte> TLS_Session::BER_encode() const
    .get_contents();
    }
 
+MemoryVector<byte>
+TLS_Session::encrypt(const SymmetricKey& master_key,
+                     const MemoryRegion<byte>& key_name,
+                     RandomNumberGenerator& rng)
+   {
+   if(key_name.size() != 16)
+      throw Encoding_Error("Bad length " + to_string(key_name.size()) +
+                           " for key_name in TLS_Session::encrypt");
+
+   if(master_key.length() == 0)
+      throw Decoding_Error("TLS_Session master_key not set");
+
+   std::auto_ptr<KDF> kdf(get_kdf("KDF2(SHA-256)"));
+
+   SymmetricKey aes_key = kdf->derive_key(16, master_key.bits_of(),
+                                          "session-ticket.cipher-key");
+
+   SymmetricKey hmac_key = kdf->derive_key(32, master_key.bits_of(),
+                                           "session-ticket.hmac-key");
+
+   InitializationVector aes_iv(rng, 16);
+
+   std::auto_ptr<MessageAuthenticationCode> mac(get_mac("HMAC(SHA-256)"));
+   mac->set_key(hmac_key);
+
+   Pipe pipe(get_cipher("AES-128/CBC", aes_key, aes_iv, ENCRYPTION));
+   pipe.process_msg(BER_encode());
+   MemoryVector<byte> ctext = pipe.read_all(0);
+
+   MemoryVector<byte> out;
+   out += key_name;
+   out += aes_iv.bits_of();
+   out += ctext;
+
+   mac->update(out);
+
+   out += mac->final();
+   return out;
+   }
+
+TLS_Session TLS_Session::decrypt(const MemoryRegion<byte>& buf,
+                                 const SymmetricKey& master_key,
+                                 const MemoryRegion<byte>& key_name)
+   {
+   try
+      {
+      if(buf.size() < (16 + 16 + 32 + 1))
+         throw Decoding_Error("Encrypted TLS_Session too short to be real");
+
+      if(master_key.length() == 0)
+         throw Decoding_Error("TLS_Session master_key not set");
+
+      if(key_name.size() != 16)
+         throw Decoding_Error("Bad length " + to_string(key_name.size()) +
+                              " for key_name");
+
+      std::auto_ptr<KDF> kdf(get_kdf("KDF2(SHA-256)"));
+
+      SymmetricKey hmac_key = kdf->derive_key(32, master_key.bits_of(),
+                                              "session-ticket.hmac-key");
+
+      std::auto_ptr<MessageAuthenticationCode> mac(get_mac("HMAC(SHA-256)"));
+      mac->set_key(hmac_key);
+
+      mac->update(&buf[0], buf.size() - 32);
+      MemoryVector<byte> computed_mac = mac->final();
+
+      if(!same_mem(&buf[buf.size() - 32], &computed_mac[0], computed_mac.size()))
+         throw Decoding_Error("MAC verification failed");
+
+      SymmetricKey aes_key = kdf->derive_key(16, master_key.bits_of(),
+                                             "session-ticket.cipher-key");
+
+      InitializationVector aes_iv(&buf[16], 16);
+
+      Pipe pipe(get_cipher("AES-128/CBC", aes_key, aes_iv, DECRYPTION));
+      pipe.process_msg(&buf[16], buf.size() - (16 + 32));
+      MemoryVector<byte> ber = pipe.read_all();
+
+      return TLS_Session(&ber[0], ber.size());
+      }
+   catch(...)
+      {
+      throw Decoding_Error("Failed to decrypt encrypted session");
+      }
+   }
+
+
 }