elgamal sample.txt

elgamal的源程序

uses GInt, PrimeGeneration, ElGamal;

procedure ElGamalSignAndVerify;
var
  p, phi, g, x, y, k, one, two, temp, gcd: TGInt;
  test, a, b: string;
  ok: boolean;
begin
 // Enter a random number to generate a prime, i.e.
 // incremental search starting from that number
  DecStrtoGInt('102336547456161301', p);
  PrimeSearch(p);
 // Compute phi(p)
  GIntCopy(p, phi);
  phi^.value := phi^.value - 1;
 // x is your secret key
  DecStrToGInt('1203', x);
 // g is any number
  DecStrToGInt('21316465461203', g);
 // k a random value, such that GCD(k,phi)=1, NEVER use the same k twice
  DecStrToGInt('1131', k);

  DecStrToGInt('1', one);
  DecStrToGInt('2', two);
  GIntGCD(phi, k, gcd);
  while GIntCompareAbs(gcd, one) <> Eq do
  begin
    GIntDestroy(gcd);
    GIntadd(k, two, temp);
    GIntDestroy(k);
    k := temp;
    GIntGCD(phi, k, gcd);
  end;
  GIntDestroy(two);
  GIntDestroy(one);
  GIntDestroy(gcd);
 // Now everything is set up to sign and verify
  test := 'eagles may soar high, but weasles do not get sucked into jet engines';

  ElGamalSign(test, p, g, x, k, a, b);
 // a and b form the signature
 // compute a public key from the secret key: g^x = mod p
  GIntModExp(g, x, p, y);
  ElGamalVerify(g, y, p, a, b, test, ok);

end;


procedure ElGamalEncryptAndDecrypt;
var
  test: string;
  p, g, x, y, k: TGInt;
begin
// Setting up parameters
// p a prime number
  DecStrToGInt('56683406451', p);
  PrimeSearch(p);
// g,x any numbers, x is your secret key
  DecStrToGInt('7675', g);
  DecStrToGInt('561', x);
// k a random number, never use the same k twice
  DecStrToGInt('10651', k);
// y = g^x mod p
  GIntModExp(g, x, p, y);

// Now everything is set up to start encrypting and decrypting
  test := 'A conscience is what hurts when all your other parts feel so good.';
  ElGamalEncrypt(test, g, y, k, p, test);
  ElGamalDecrypt(test, x, p, test);

  GIntDestroy(p);
  GIntDestroy(g);
  GIntDestroy(x);
  GIntDestroy(y);
  GIntDestroy(k);
end;