1 files changed, 98 insertions, 0 deletions
diff --git a/lib/pubkey/dh/dh.cpp b/lib/pubkey/dh/dh.cpp
new file mode 100644
index 000000000..55d53518a
--- /dev/null
+++ b/lib/pubkey/dh/dh.cpp
@@ -0,0 +1,98 @@
+/*
+* Diffie-Hellman
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/dh.h>
+#include <botan/numthry.h>
+#include <botan/workfactor.h>
+
+namespace Botan {
+
+/*
+* DH_PublicKey Constructor
+*/
+DH_PublicKey::DH_PublicKey(const DL_Group& grp, const BigInt& y1)
+   {
+   group = grp;
+   y = y1;
+   }
+
+/*
+* Return the public value for key agreement
+*/
+std::vector<byte> DH_PublicKey::public_value() const
+   {
+   return unlock(BigInt::encode_1363(y, group_p().bytes()));
+   }
+
+/*
+* Create a DH private key
+*/
+DH_PrivateKey::DH_PrivateKey(RandomNumberGenerator& rng,
+                             const DL_Group& grp,
+                             const BigInt& x_arg)
+   {
+   group = grp;
+   x = x_arg;
+
+   if(x == 0)
+      {
+      const BigInt& p = group_p();
+      x.randomize(rng, 2 * dl_work_factor(p.bits()));
+      }
+
+   if(y == 0)
+      y = power_mod(group_g(), x, group_p());
+
+   if(x == 0)
+      gen_check(rng);
+   else
+      load_check(rng);
+   }
+
+/*
+* Load a DH private key
+*/
+DH_PrivateKey::DH_PrivateKey(const AlgorithmIdentifier& alg_id,
+                             const secure_vector<byte>& key_bits,
+                             RandomNumberGenerator& rng) :
+   DL_Scheme_PrivateKey(alg_id, key_bits, DL_Group::ANSI_X9_42)
+   {
+   if(y == 0)
+      y = power_mod(group_g(), x, group_p());
+
+   load_check(rng);
+   }
+
+/*
+* Return the public value for key agreement
+*/
+std::vector<byte> DH_PrivateKey::public_value() const
+   {
+   return DH_PublicKey::public_value();
+   }
+
+DH_KA_Operation::DH_KA_Operation(const DH_PrivateKey& dh,
+                                 RandomNumberGenerator& rng) :
+   p(dh.group_p()), powermod_x_p(dh.get_x(), p)
+   {
+   BigInt k(rng, p.bits() - 1);
+   blinder = Blinder(k, powermod_x_p(inverse_mod(k, p)), p);
+   }
+
+secure_vector<byte> DH_KA_Operation::agree(const byte w[], size_t w_len)
+   {
+   BigInt input = BigInt::decode(w, w_len);
+
+   if(input <= 1 || input >= p - 1)
+      throw Invalid_Argument("DH agreement - invalid key provided");
+
+   BigInt r = blinder.unblind(powermod_x_p(blinder.blind(input)));
+
+   return BigInt::encode_1363(r, p.bytes());
+   }
+
+}