UT_ECurve.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        UT_ECurve.h ( UT Library, C++)
 *
 * COMMENTS:    Defines an elliptic curve over a binary Galois field -- GF(2^m)
 *              Useful for cryptography.
 */

#ifndef __UT_ECurve__
#define __UT_ECurve__

#include "UT_API.h"
#include <SYS/SYS_Types.h>
#include "UT_VeryLong.h"
#include "UT_PolyField.h"

#define UT_ECURVE_MAXBASIS      6

class UT_API UT_ECurve
{
public:
    UT_ECurve()                 { myBits = 0; }
    UT_ECurve(const uint q[],
             const char *r,
             const char *a,
             const char *b,
             const char *gx,
             const char *gy)
    {
        setQ(q);
        myR = r;
        myA = a;
        myB = b;
        myGx = gx;
        myGy = gy;
        computeBits();
    }

    void        setQ(const uint q[])
                {
                    int         i;
                    UT_VeryLong shift;
                    myQ = 1u;
                    for (i = 0; q[i]; i++)
                    {
                        myBasis[i] = q[i];
                        shift = 1;
                        shift <<= q[i];
                        myQ += shift;
                    }
                    myBasis[i] = 1;
                    for (i = i+1; i < UT_ECURVE_MAXBASIS; i++)
                        myBasis[i] = 0;
                }
    void        setR(int x)                     { myR = x; computeBits(); }
    void        setR(const char *x)             { myR = x; computeBits(); }
    void        setR(const UT_VeryLong &x)      { myR = x; computeBits(); }
    void        setA(int x)                     { myA = x; }
    void        setA(const char *x)             { myA = x; }
    void        setA(const UT_PolyField &x)     { myA = x; }
    void        setB(int x)                     { myB = x; }
    void        setB(const char *x)             { myB = x; }
    void        setB(const UT_PolyField &x)     { myB = x; }
    void        setGx(int x)                    { myGx = x; }
    void        setGx(const char *x)            { myGx = x; }
    void        setGx(const UT_PolyField &x)    { myGx = x; }
    void        setGy(int x)                    { myGy = x; }
    void        setGy(const char *x)            { myGy = x; }
    void        setGy(const UT_PolyField &x)    { myGy = x; }

    const UT_VeryLong   &getR() const           { return myR; }
    const UT_PolyField  &getQ() const           { return myQ; }
    const UT_PolyField  &getA() const           { return myA; }
    const UT_PolyField  &getB() const           { return myB; }
    const UT_PolyField  &getGx() const          { return myGx; }
    const UT_PolyField  &getGy() const          { return myGy; }

    // ECC methods
    void        generateRandom(UT_VeryLong &r,
                                const uint *seed, uint seedlen) const;
    bool        generateRandomRaw(UT_VeryLong &r,
                                const uint *seed, uint len) const;
    void        generatePublic(UT_PolyField &pubx, UT_PolyField &puby,
                                const UT_VeryLong &key) const;

    // Create a digital signature for m with a random key r and return the
    // result in codea/codeb.  If the encoding failed, return 0
    bool        dsa(UT_VeryLong &acode, UT_VeryLong &bcode,
                    const UT_VeryLong &key, const UT_VeryLong &r,
                    const UT_VeryLong &m) const;

    void        partialDSA(UT_VeryLong &code,
                    const UT_VeryLong &key, const UT_VeryLong &rnd) const;

    // Verify the digital signature of m given codea/codeb
    bool        verify(const UT_VeryLong &m,
                    const UT_VeryLong &code, const UT_VeryLong &codeb,
                    const UT_PolyField &pubx, const UT_PolyField &puby) const;

    void        dump(int base=16) const;

private:
    void        computeBits();
    void        mult(UT_PolyField &x, UT_PolyField &y,
                        const UT_VeryLong &m) const
                {
                    mult(x, y, m, myGx, myGy);
                }
    void        mult(UT_PolyField &x, UT_PolyField &y, const UT_VeryLong &m,
                        const UT_PolyField &gx, const UT_PolyField &gy) const;

    void        curveDouble(UT_PolyField &x, UT_PolyField &y) const;
    void        curveAdd(UT_PolyField &dx, UT_PolyField &dy,
                        const UT_PolyField &sx, const UT_PolyField &sy,
                        const UT_PolyField &gx, const UT_PolyField &gy) const;

    UT_VeryLong         myR;
    UT_PolyField        myQ;
    UT_PolyField        myA, myB;
    UT_PolyField        myGx, myGy;
    int                 myBits;
    int                 myBasis[6];
};

#endif