1 files changed, 96 insertions, 0 deletions
diff --git a/src/lib/pubkey/elgamal/elgamal.h b/src/lib/pubkey/elgamal/elgamal.h
new file mode 100644
index 000000000..9566bcca6
--- /dev/null
+++ b/src/lib/pubkey/elgamal/elgamal.h
@@ -0,0 +1,96 @@
+/*
+* ElGamal
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_ELGAMAL_H__
+#define BOTAN_ELGAMAL_H__
+
+#include <botan/dl_algo.h>
+#include <botan/numthry.h>
+#include <botan/reducer.h>
+#include <botan/blinding.h>
+#include <botan/pk_ops.h>
+
+namespace Botan {
+
+/**
+* ElGamal Public Key
+*/
+class BOTAN_DLL ElGamal_PublicKey : public virtual DL_Scheme_PublicKey
+   {
+   public:
+      std::string algo_name() const { return "ElGamal"; }
+      DL_Group::Format group_format() const { return DL_Group::ANSI_X9_42; }
+
+      size_t max_input_bits() const { return (group_p().bits() - 1); }
+
+      ElGamal_PublicKey(const AlgorithmIdentifier& alg_id,
+                        const secure_vector<byte>& key_bits) :
+         DL_Scheme_PublicKey(alg_id, key_bits, DL_Group::ANSI_X9_42)
+         {}
+
+      ElGamal_PublicKey(const DL_Group& group, const BigInt& y);
+   protected:
+      ElGamal_PublicKey() {}
+   };
+
+/**
+* ElGamal Private Key
+*/
+class BOTAN_DLL ElGamal_PrivateKey : public ElGamal_PublicKey,
+                                     public virtual DL_Scheme_PrivateKey
+   {
+   public:
+      bool check_key(RandomNumberGenerator& rng, bool) const;
+
+      ElGamal_PrivateKey(const AlgorithmIdentifier& alg_id,
+                         const secure_vector<byte>& key_bits,
+                         RandomNumberGenerator& rng);
+
+      ElGamal_PrivateKey(RandomNumberGenerator& rng,
+                         const DL_Group& group,
+                         const BigInt& priv_key = 0);
+   };
+
+/**
+* ElGamal encryption operation
+*/
+class BOTAN_DLL ElGamal_Encryption_Operation : public PK_Ops::Encryption
+   {
+   public:
+      size_t max_input_bits() const { return mod_p.get_modulus().bits() - 1; }
+
+      ElGamal_Encryption_Operation(const ElGamal_PublicKey& key);
+
+      secure_vector<byte> encrypt(const byte msg[], size_t msg_len,
+                                 RandomNumberGenerator& rng);
+
+   private:
+      Fixed_Base_Power_Mod powermod_g_p, powermod_y_p;
+      Modular_Reducer mod_p;
+   };
+
+/**
+* ElGamal decryption operation
+*/
+class BOTAN_DLL ElGamal_Decryption_Operation : public PK_Ops::Decryption
+   {
+   public:
+      size_t max_input_bits() const { return mod_p.get_modulus().bits() - 1; }
+
+      ElGamal_Decryption_Operation(const ElGamal_PrivateKey& key,
+                                   RandomNumberGenerator& rng);
+
+      secure_vector<byte> decrypt(const byte msg[], size_t msg_len);
+   private:
+      Fixed_Exponent_Power_Mod powermod_x_p;
+      Modular_Reducer mod_p;
+      Blinder blinder;
+   };
+
+}
+
+#endif