src/Rsa.cpp

   1 #include "Rsa.h"
   2
   3 using namespace std;
   4
   5 #include "Rand.h"
   6 #include "Utils.h"
   7
   8 pair<Rsa::KeyPub, Rsa::KeyPriv> Rsa::generateRSAKeys(uint exponent, uint keySizeBits)
   9 {
  10    mpz_class p, q, phi;
  11    KeyPub kPub;
  12    KeyPriv kPriv;
  13
  14    do
  15    {
  16       kPub.e = exponent;
  17       p = Rand::randPrime(keySizeBits / 2);
  18       q = Rand::randPrime(keySizeBits / 2);
  19
  20       kPriv.n = kPub.n = p * q;
  21       phi = (p - 1) * (q - 1);
  22
  23    } while (mpz_invert(kPriv.d.get_mpz_t(), kPub.e.get_mpz_t(), phi.get_mpz_t()) == 0);
  24
  25 // For debugging purpose.
  26 //   print("p", p);
  27 //   print("q", q);
  28 //   print("n", kPub.n);
  29 //   print("phi", phi);
  30 //   print("d", kPriv.d);
  31
  32    return make_pair(kPub, kPriv);
  33 }
  34
  35 mpz_class Rsa::sign(const mpz_class& m, const KeyPriv& kPriv)
  36 {
  37    mpz_class result;
  38    mpz_powm_sec(result.get_mpz_t(), m.get_mpz_t(), kPriv.d.get_mpz_t(), kPriv.n.get_mpz_t());
  39    return result;
  40 }
  41
  42 bool Rsa::verifySignature(const mpz_class& m, const mpz_class& sig, const KeyPub& kPub)
  43 {
  44    mpz_class mPrime;
  45    mpz_powm_sec(mPrime.get_mpz_t(), sig.get_mpz_t(), kPub.e.get_mpz_t(), kPub.n.get_mpz_t());
  46    return m == mPrime;
  47 }