Modularize the public key algorithms, though currently a great deal of

the underlying implementation goop remains in the core library instead of
being shunted off, due to various dependencies it has (most of which it
shouldn't).

1 files changed, 121 insertions, 0 deletions

diff --git a/src/pk/elgamal/elgamal.cpp b/src/pk/elgamal/elgamal.cpp
new file mode 100644
index 000000000..ea0d581b0
--- /dev/null
+++ b/src/pk/elgamal/elgamal.cpp
@@ -0,0 +1,121 @@
+/*************************************************
+* ElGamal Source File                            *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/elgamal.h>
+#include <botan/numthry.h>
+#include <botan/keypair.h>
+#include <botan/util.h>
+
+namespace Botan {
+
+/*************************************************
+* ElGamal_PublicKey Constructor                  *
+*************************************************/
+ElGamal_PublicKey::ElGamal_PublicKey(const DL_Group& grp, const BigInt& y1)
+   {
+   group = grp;
+   y = y1;
+   X509_load_hook();
+   }
+
+/*************************************************
+* Algorithm Specific X.509 Initialization Code   *
+*************************************************/
+void ElGamal_PublicKey::X509_load_hook()
+   {
+   core = ELG_Core(group, y);
+   }
+
+/*************************************************
+* ElGamal Encryption Function                    *
+*************************************************/
+SecureVector<byte>
+ElGamal_PublicKey::encrypt(const byte in[], u32bit length,
+                           RandomNumberGenerator& rng) const
+   {
+   BigInt k(rng, 2 * dl_work_factor(group_p().bits()));
+   return core.encrypt(in, length, k);
+   }
+
+/*************************************************
+* Return the maximum input size in bits          *
+*************************************************/
+u32bit ElGamal_PublicKey::max_input_bits() const
+   {
+   return (group_p().bits() - 1);
+   }
+
+/*************************************************
+* ElGamal_PrivateKey Constructor                 *
+*************************************************/
+ElGamal_PrivateKey::ElGamal_PrivateKey(RandomNumberGenerator& rng,
+                                       const DL_Group& grp,
+                                       const BigInt& x_arg)
+   {
+   group = grp;
+   x = x_arg;
+
+   if(x == 0)
+      {
+      x.randomize(rng, 2 * dl_work_factor(group_p().bits()));
+      PKCS8_load_hook(rng, true);
+      }
+   else
+      PKCS8_load_hook(rng, false);
+   }
+
+/*************************************************
+* Algorithm Specific PKCS #8 Initialization Code *
+*************************************************/
+void ElGamal_PrivateKey::PKCS8_load_hook(RandomNumberGenerator& rng,
+                                         bool generated)
+   {
+   if(y == 0)
+      y = power_mod(group_g(), x, group_p());
+   core = ELG_Core(rng, group, y, x);
+
+   if(generated)
+      gen_check(rng);
+   else
+      load_check(rng);
+   }
+
+/*************************************************
+* ElGamal Decryption Function                    *
+*************************************************/
+SecureVector<byte> ElGamal_PrivateKey::decrypt(const byte in[],
+                                               u32bit length) const
+   {
+   return core.decrypt(in, length);
+   }
+
+/*************************************************
+* Check Private ElGamal Parameters               *
+*************************************************/
+bool ElGamal_PrivateKey::check_key(RandomNumberGenerator& rng,
+                                   bool strong) const
+   {
+   if(!DL_Scheme_PrivateKey::check_key(rng, strong))
+      return false;
+
+   if(!strong)
+      return true;
+
+   try
+      {
+      KeyPair::check_key(rng,
+                         get_pk_encryptor(*this, "EME1(SHA-1)"),
+                         get_pk_decryptor(*this, "EME1(SHA-1)")
+         );
+      }
+   catch(Self_Test_Failure)
+      {
+      return false;
+      }
+
+   return true;
+   }
+
+}