1 files changed, 97 insertions, 0 deletions
diff --git a/botan/src/pubkey/elgamal/elg_core.cpp b/botan/src/pubkey/elgamal/elg_core.cpp
new file mode 100644
index 0000000..8b8c8f5
--- /dev/null
+++ b/botan/src/pubkey/elgamal/elg_core.cpp
@@ -0,0 +1,97 @@
+/*
+* ElGamal Core
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/elg_core.h>
+#include <botan/numthry.h>
+#include <botan/pk_engine.h>
+#include <botan/parsing.h>
+#include <algorithm>
+
+namespace Botan {
+
+namespace {
+
+const u32bit BLINDING_BITS = BOTAN_PRIVATE_KEY_OP_BLINDING_BITS;
+
+}
+
+/*
+* ELG_Core Constructor
+*/
+ELG_Core::ELG_Core(const DL_Group& group, const BigInt& y)
+   {
+   op = Engine_Core::elg_op(group, y, 0);
+   p_bytes = 0;
+   }
+
+/*
+* ELG_Core Constructor
+*/
+ELG_Core::ELG_Core(RandomNumberGenerator& rng,
+                   const DL_Group& group, const BigInt& y, const BigInt& x)
+   {
+   op = Engine_Core::elg_op(group, y, x);
+
+   const BigInt& p = group.get_p();
+   p_bytes = p.bytes();
+
+   if(BLINDING_BITS)
+      {
+      BigInt k(rng, std::min(p.bits()-1, BLINDING_BITS));
+      blinder = Blinder(k, power_mod(k, x, p), p);
+      }
+   }
+
+/*
+* ELG_Core Copy Constructor
+*/
+ELG_Core::ELG_Core(const ELG_Core& core)
+   {
+   op = 0;
+   if(core.op)
+      op = core.op->clone();
+   blinder = core.blinder;
+   p_bytes = core.p_bytes;
+   }
+
+/*
+* ELG_Core Assignment Operator
+*/
+ELG_Core& ELG_Core::operator=(const ELG_Core& core)
+   {
+   delete op;
+   if(core.op)
+      op = core.op->clone();
+   blinder = core.blinder;
+   p_bytes = core.p_bytes;
+   return (*this);
+   }
+
+/*
+* ElGamal Encrypt Operation
+*/
+SecureVector<byte> ELG_Core::encrypt(const byte in[], u32bit length,
+                                     const BigInt& k) const
+   {
+   return op->encrypt(in, length, k);
+   }
+
+/*
+* ElGamal Decrypt Operation
+*/
+SecureVector<byte> ELG_Core::decrypt(const byte in[], u32bit length) const
+   {
+   if(length != 2*p_bytes)
+      throw Invalid_Argument("ELG_Core::decrypt: Invalid message");
+
+   BigInt a(in, p_bytes);
+   BigInt b(in + p_bytes, p_bytes);
+
+   return BigInt::encode(blinder.unblind(op->decrypt(blinder.blind(a), b)));
+   }
+
+}