public static void CreateAsymetricKey(int strength, out string privateKey, out string publicKey)
{
RsaKeyPair keyPair = RSA.GenerateKeyPair(strength);
privateKey = keyPair.PrivateKey.ToXmlString();
publicKey = keyPair.PublicKey.ToXmlString();
}
public static RsaKeyPair GenerateKeyPair(int strength, int certainity, BigInteger publicExponent)
{
BigInteger p, q, n, d, e, pSub1, qSub1, phi;
// This is cryptographic stuff, we want to use the secure random provider
Random rand = RandomGenerator.GetSecureRandomGenerator();
//
// p and q values should have a length of half the strength in bits
//
int pbitlength = (strength + 1) / 2;
int qbitlength = (strength - pbitlength);
e = publicExponent;
//
// Generate p, prime and (p-1) relatively prime to e
//
for (; ;)
{
p = new BigInteger(pbitlength, certainity, rand);
if (e.Gcd(p.Subtract(BigInteger.One)).Equals(BigInteger.One))
{
break;
}
}
//
// Generate a modulus of the required length
//
for (; ;)
{
// Generate q, prime and (q-1) relatively prime to e,
// and not equal to p
//
for (; ;)
{
q = new BigInteger(qbitlength, certainity, rand);
if (e.Gcd(q.Subtract(BigInteger.One)).Equals(BigInteger.One) && !p.Equals(q))
{
break;
}
}
//
// calculate the modulus
//
n = p.Multiply(q);
if (n.BitLength() == strength)
{
break;
}
//
// if we Get here our primes aren't big enough, make the largest
// of the two p and try again
//
p = p.Max(q);
}
pSub1 = p.Subtract(BigInteger.One);
qSub1 = q.Subtract(BigInteger.One);
phi = pSub1.Multiply(qSub1);
//
// calculate the private exponent
//
d = e.ModInverse(phi);
//
// calculate the CRT factors
//
BigInteger dP, dQ, qInv;
dP = d.Remainder(pSub1);
dQ = d.Remainder(qSub1);
qInv = q.ModInverse(p);
RsaKey publicKey = new RsaKey(false, n, e);
RsaPrivateKey privateKey = new RsaPrivateKey(n, e, d, p, q, dP, dQ, qInv);
RsaKeyPair pair = new RsaKeyPair(privateKey, publicKey);
return(pair);
}
