src/RsaCrt.cpp

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