public void SetSessionKey(String pubKeyString, String scrambler = null)
{
BigInteger pubKey = BigIntegerExtension.Create(pubKeyString, 16);
if (scrambler == null) // Server SessionKey
{
// (Av^u) ^ b (mod N)
SessionKey = pubKey.multiply(verifier.modPow(Scrambler, Modulus)).modPow(PrivateKey, Modulus);
}
else // Client SessionKey
{
Scrambler = BigIntegerExtension.Create(scrambler, 16);
BigInteger temp = PrivateKey.add(Scrambler.multiply(SaltedIdentityHash));
SessionKey = pubKey.subtract((Generator.modPow(SaltedIdentityHash, Modulus)).multiply(Multiplier)).modPow(temp, Modulus);
}
}
// Client Constructor, username not needed, salt not generated by client
public SRP6(byte[] identityHash, String modulus_N, int generator_g,
String salt, string initialVector = "OFRna73m*aze01xY")
{
InitialVector = initialVector;
Modulus = BigIntegerExtension.Create(modulus_N, 16);
Generator = BigIntegerExtension.Create("" + generator_g, 10);
Multiplier = BigIntegerExtension.Create("3", 10);
Salt = BigIntegerExtension.Create(salt, 16);
// Client-side variables
PrivateKey = BigIntegerExtension.GeneratePseudoPrime(128, 100, new Random());
// g^a (mod N)
PublicKey = this.generator_g.modPow(privateKey, this.modulus_N);
// Server-side variables
SaltedIdentityHash = bytesToBig(Sha1Hash(Salt.ToByteArray(), identityHash));
}
// Server Constructor, Radix 16 strings, 256-bit predef values
public SRP6(byte[] identity, String modulus_N, int generator_g, int saltBits,
int scramblerBits, string initialVector = "OFRna73m*aze01xY")
{
InitialVector = initialVector;
Modulus = BigIntegerExtension.Create(modulus_N, 16);
Generator = BigIntegerExtension.Create("" + generator_g, 10);
Multiplier = BigIntegerExtension.Create("3", 10);
Salt = BigIntegerExtension.Create(saltBits, new Random());
Scrambler = BigIntegerExtension.Create(scramblerBits, new Random());
// Server-side variables
IdentityHash = identity;
SaltedIdentityHash = bytesToBig(Sha1Hash(salt.ToByteArray(), identity));
Verifier = this.generator_g.modPow(saltedIdentityHash, this.modulus_N);
// Random 128 bit number that is a probable prime
PrivateKey = BigIntegerExtension.GeneratePseudoPrime(128, 100, new Random());
// kv + g^b (mod N)
PublicKey = this.multiplier_k.multiply(verifier).add(this.generator_g.modPow(privateKey, this.modulus_N));
}
private static BigInteger bytesToBig(byte[] bytes)
{
return(BigIntegerExtension.Create(BytesToHex(bytes), 16));
}
