dgk.h

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/*
SeComLib
Copyright 2012-2013 TU Delft, Information Security & Privacy Lab (http://isplab.tudelft.nl/)

Contributors:
Inald Lagendijk (R.L.Lagendijk@TUDelft.nl)
Mihai Todor (todormihai@gmail.com)
Thijs Veugen (P.J.M.Veugen@tudelft.nl)
Zekeriya Erkin (z.erkin@tudelft.nl)

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#ifndef DGK_HEADER_GUARD
#define DGK_HEADER_GUARD

#include "big_integer.h"
#include "ciphertext_base.h"
#include "crypto_provider.h"
#include "random_provider.h"
#include "utils/config.h"

//include C++ headers
#include <stdexcept>
#include <map>

namespace SeComLib {
namespace Core {
    struct DgkPublicKey {
    public:
        BigInteger n;
        BigInteger g;
        BigInteger h;
        BigInteger u;
    };

    struct DgkPrivateKey {
    public:
        BigInteger p;
        BigInteger q;
        BigInteger vp;
        BigInteger vq;
    };

    class DgkCiphertext : public CiphertextBase<DgkCiphertext> {
    public:
        DgkCiphertext ();

        DgkCiphertext (const std::shared_ptr<BigInteger> &encryptionModulus);

        DgkCiphertext (const BigInteger &data, const std::shared_ptr<BigInteger> &encryptionModulus);
    };

    struct DgkRandomizer : public RandomizerBase {
        DgkRandomizer ();

        DgkRandomizer (const BigInteger &data);
    };

    class Dgk : public CryptoProvider<DgkPublicKey, DgkPrivateKey, DgkCiphertext, DgkRandomizer> {
    public:
        Dgk (const bool precomputeDecryptionMap = false);

        Dgk (const DgkPublicKey &publicKey);

        Dgk (const DgkPublicKey &publicKey, const DgkPrivateKey &privateKey, const bool precomputeDecryptionMap = false);

        ~Dgk () {}

        /* Base class methods */

        virtual bool GenerateKeys ();

        virtual BigInteger DecryptInteger (const Ciphertext &ciphertext) const;

        virtual Ciphertext EncryptIntegerNonrandom (const BigInteger &plaintext) const;

        virtual Randomizer GetRandomizer () const;

        virtual Ciphertext RandomizeCiphertext (const Ciphertext &ciphertext) const;

        virtual const BigInteger &GetMessageSpaceUpperBound () const;

        virtual size_t GetMessageSpaceSize () const;

        /* /Base class methods */

        bool IsEncryptedZero (const Ciphertext &ciphertext) const;

    private:
        typedef std::map<const BigInteger, BigInteger> DecryptionMap;

        const unsigned int t;

        const unsigned int l;

        bool precomputeDecryptionMap;

        DecryptionMap decryptionMap;

        BigInteger pTimesPInvModQ;
        BigInteger qTimesQInvModP;

        /* Base class methods */

        virtual void validateParameters ();

        virtual void doPrecomputations ();

        /* /Base class methods */

        Dgk (const Dgk &);

        Dgk operator= (const Dgk &);
    };
}//namespace Core
}//namespace SeComLib

#endif//DGK_HEADER_GUARD