secure_svm.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 SECURE_SVM_HEADER_GUARD
#define SECURE_SVM_HEADER_GUARD

//include our headers
#include "utils/config.h"
#include "core/big_integer.h"
#include "core/paillier.h"

//include 3rd party libraries
#include "libsvm/svm.h"
#include "boost/assign.hpp"

//include C++ libraries
#include <iostream>
#include <cmath>
#include <stdexcept>
#include <fstream>
#include <vector>
#include <map>

namespace SeComLib {
using namespace Core;

namespace SecureRecommendations {
    //forward-declare required classes
    class Server;

    class SecureSvm {
    public:
        typedef std::vector<Paillier::Ciphertext> EncryptedVector;

        static const EncryptedVector nullVector;

        enum KernelTypes {linear, homogeneousPolynomial, inhomogeneousPolynomial, inverseQuadraticRBF};

        SecureSvm (const std::string &directoryPath, const std::string &modelFile, const PaillierPublicKey &publicKey, const std::weak_ptr<const Server> &server);

        ~SecureSvm ();

        static KernelTypes GetKernel (const std::string &input);

        const std::string &GetUnsafeClasses () const;

        Paillier::Ciphertext Predict (const SecureSvm::EncryptedVector &x, const SecureSvm::EncryptedVector &xx = SecureSvm::nullVector, const SecureSvm::EncryptedVector &xSquared = SecureSvm::nullVector) const;

    private:
        Paillier cryptoProvider;

        std::weak_ptr<const Server> server;

        static const std::map<std::string, KernelTypes> kernelTypesMap;

        typedef std::vector<BigInteger> ModelVector;

        SecureSvm::KernelTypes kernel;

        std::string modelFileName;

        struct svm_model *model;

        BigInteger featureScalingFactor;

        BigInteger svWeightScaling;

        unsigned short minimumAiDecimalDigits;

        unsigned short inverseQuadraticRbfKernelRelevantDigits;

        BigInteger inverseQuadraticRbfNumerator;

        BigInteger blindingFactorScaling;

        BigInteger gammaScaling;

        bool reversedSign;

        std::vector<ModelVector> sMatrix;

        std::vector<ModelVector> twoGammaSMatrix;

        std::vector<ModelVector> minusTwoSMatrix;

        std::vector<ModelVector> twoGammaSquaredSSMatrix;

        std::vector<EncryptedVector> encryptedSSquaredMatrix;

        std::vector<BigInteger> aVector;

        Paillier::Ciphertext encryptedB;

        BigInteger scaledGamma;

        Paillier::Ciphertext encryptedZero;

        Paillier::Ciphertext encryptedScaledOne;

        std::string safetyModelFilePrefix;

        std::string safetyModelUnsafeClasses;

        void preprocessData ();

        Paillier::Ciphertext linearKernel (const SecureSvm::EncryptedVector &x, const SecureSvm::ModelVector &s) const;

        Paillier::Ciphertext homogeneousPolynomialKernel (const SecureSvm::EncryptedVector &xx, const SecureSvm::ModelVector &twoGammaSquaredSS) const;

        Paillier::Ciphertext inhomogeneousPolynomialKernel (const SecureSvm::EncryptedVector &x, const SecureSvm::EncryptedVector &xx, const SecureSvm::ModelVector &twoGammaS, const SecureSvm::ModelVector &twoGammaSquaredSS) const;

        Paillier::Ciphertext computeInverseQuadraticRbfKernelDenominator (const SecureSvm::EncryptedVector &x, const SecureSvm::EncryptedVector &xSquared, const SecureSvm::ModelVector &minusTwoS, const SecureSvm::EncryptedVector &encryptedSSquared) const;

        SecureSvm (SecureSvm const &);

        SecureSvm operator= (SecureSvm const &);
    };
}//namespace SecureRecommendations
}//namespace SeComLib

#endif//SECURE_SVM_HEADER_GUARD