rsa.h

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/* Copyright 2009 Andreas Gölzer

This file is part of readESM.

readESM is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

readESM is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with readESM.  If not, see <http://www.gnu.org/licenses/>. */
#ifndef RSA_H
#define RSA_H RSA_H

#include <gmp.h>
#include <vector>


class mpz {
        public:
        mpz_t t;
        int dummy;
        mpz() { mpz_init(t);  }
        ~mpz(){ mpz_clear(t); }
        mpz(const mpz& o){ mpz_init_set(t, o.t); }
        mpz& operator=(const mpz& o){ mpz_init_set(t, o.t); return *this; }
};

class rsa {
        public:
        rsa() {};
        rsa(unsigned char* modulus, int mlen, unsigned char* exponent, int elen){
                mpz_import(n.t, mlen, 1, 1, 0, 0, modulus);
                mpz_import(e.t, elen, 1, 1, 0, 0, exponent);
        }
        std::vector<unsigned char> perform(const unsigned char* input, int length) const{
                mpz in, out;
                mpz_import(in.t, length, 1, 1, 0, 0, input);
                mpz_powm(out.t, in.t,e.t,n.t);
                size_t size;
                std::vector<unsigned char> rv(mpz_sizeinbase(out.t, 256) + 10);
                mpz_export(&rv[0], &size, 1, 1, 0, 0, out.t);
                rv.resize(size);
                return rv;
        }
        private:
        mpz n, e;
};

#endif

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