From 0abc80f498c6bc2e8f630e34b90d5c6d24c29f58 Mon Sep 17 00:00:00 2001
From: lloyd <lloyd@randombit.net>
Date: Sat, 17 Apr 2010 17:57:14 +0000
Subject: Add support for TLS 1.2 PRF

---
 src/kdf/tls_prf/prf_tls.cpp | 59 +++++++++++++++++++++++++++++++--------------
 src/kdf/tls_prf/prf_tls.h   | 26 +++++++++++++++++---
 2 files changed, 63 insertions(+), 22 deletions(-)

(limited to 'src/kdf')

diff --git a/src/kdf/tls_prf/prf_tls.cpp b/src/kdf/tls_prf/prf_tls.cpp
index 5e77f831e..7345f11c5 100644
--- a/src/kdf/tls_prf/prf_tls.cpp
+++ b/src/kdf/tls_prf/prf_tls.cpp
@@ -1,6 +1,6 @@
 /*
-* TLS PRF
-* (C) 2004-2006 Jack Lloyd
+* TLS v1.0 and v1.2 PRFs
+* (C) 2004-2010 Jack Lloyd
 *
 * Distributed under the terms of the Botan license
 */
@@ -18,19 +18,19 @@ namespace {
 /*
 * TLS PRF P_hash function
 */
-SecureVector<byte> P_hash(MessageAuthenticationCode* mac,
-                          u32bit len,
-                          const byte secret[], u32bit secret_len,
-                          const byte seed[], u32bit seed_len)
+void P_hash(byte output[], u32bit output_len,
+            MessageAuthenticationCode* mac,
+            const byte secret[], u32bit secret_len,
+            const byte seed[], u32bit seed_len)
    {
-   SecureVector<byte> out;
-
    mac->set_key(secret, secret_len);
 
    SecureVector<byte> A(seed, seed_len);
-   while(len)
+
+   while(output_len)
       {
-      const u32bit this_block_len = std::min(mac->OUTPUT_LENGTH, len);
+      const u32bit this_block_len =
+         std::min(mac->OUTPUT_LENGTH, output_len);
 
       A = mac->process(A);
 
@@ -38,10 +38,10 @@ SecureVector<byte> P_hash(MessageAuthenticationCode* mac,
       mac->update(seed, seed_len);
       SecureVector<byte> block = mac->final();
 
-      out.append(block, this_block_len);
-      len -= this_block_len;
+      xor_buf(output, &block[0], this_block_len);
+      output_len -= this_block_len;
+      output += this_block_len;
       }
-   return out;
    }
 
 }
@@ -68,18 +68,41 @@ SecureVector<byte> TLS_PRF::derive(u32bit key_len,
                                    const byte secret[], u32bit secret_len,
                                    const byte seed[], u32bit seed_len) const
    {
+   SecureVector<byte> output(key_len);
+
    u32bit S1_len = (secret_len + 1) / 2,
           S2_len = (secret_len + 1) / 2;
    const byte* S1 = secret;
    const byte* S2 = secret + (secret_len - S2_len);
 
-   SecureVector<byte> key1, key2;
-   key1 = P_hash(hmac_md5,  key_len, S1, S1_len, seed, seed_len);
-   key2 = P_hash(hmac_sha1, key_len, S2, S2_len, seed, seed_len);
+   P_hash(output, key_len, hmac_md5,  S1, S1_len, seed, seed_len);
+   P_hash(output, key_len, hmac_sha1, S2, S2_len, seed, seed_len);
+
+   return output;
+   }
+
+/*
+* TLS v1.2 PRF Constructor and Destructor
+*/
+TLS_12_PRF::TLS_12_PRF(HashFunction* hash)
+   {
+   hmac = new HMAC(hash);
+   }
+
+TLS_12_PRF::~TLS_12_PRF()
+   {
+   delete hmac;
+   }
+
+SecureVector<byte> TLS_12_PRF::derive(u32bit key_len,
+                                      const byte secret[], u32bit secret_len,
+                                      const byte seed[], u32bit seed_len) const
+   {
+   SecureVector<byte> output(key_len);
 
-   xor_buf(key1.begin(), key2.begin(), key2.size());
+   P_hash(output, key_len, hmac, secret, secret_len, seed, seed_len);
 
-   return key1;
+   return output;
    }
 
 }
diff --git a/src/kdf/tls_prf/prf_tls.h b/src/kdf/tls_prf/prf_tls.h
index d21279588..6d1787609 100644
--- a/src/kdf/tls_prf/prf_tls.h
+++ b/src/kdf/tls_prf/prf_tls.h
@@ -1,6 +1,6 @@
 /*
-* TLS v1.0 PRF
-* (C) 1999-2007 Jack Lloyd
+* TLS v1.0 and v1.2 PRFs
+* (C) 2004-2010 Jack Lloyd
 *
 * Distributed under the terms of the Botan license
 */
@@ -10,6 +10,7 @@
 
 #include <botan/kdf.h>
 #include <botan/mac.h>
+#include <botan/hash.h>
 
 namespace Botan {
 
@@ -19,8 +20,9 @@ namespace Botan {
 class BOTAN_DLL TLS_PRF : public KDF
    {
    public:
-      SecureVector<byte> derive(u32bit, const byte[], u32bit,
-                                const byte[], u32bit) const;
+      SecureVector<byte> derive(u32bit key_len,
+                                const byte secret[], u32bit secret_len,
+                                const byte seed[], u32bit seed_len) const;
 
       TLS_PRF();
       ~TLS_PRF();
@@ -29,6 +31,22 @@ class BOTAN_DLL TLS_PRF : public KDF
       MessageAuthenticationCode* hmac_sha1;
    };
 
+/*
+* TLS 1.2 PRF
+*/
+class BOTAN_DLL TLS_12_PRF : public KDF
+   {
+   public:
+      SecureVector<byte> derive(u32bit key_len,
+                                const byte secret[], u32bit secret_len,
+                                const byte seed[], u32bit seed_len) const;
+
+      TLS_12_PRF(HashFunction* hash);
+      ~TLS_12_PRF();
+   private:
+      MessageAuthenticationCode* hmac;
+   };
+
 }
 
 #endif
-- 
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