static byte[] ComputeHash(Algo algo, string passwordStr)
{
var salt1 = algo.Salt1.ToArrayUnsafe();
var salt2 = algo.Salt2.ToArrayUnsafe();
var passwordBytes = Encoding.UTF8.GetBytes(passwordStr);
var hash1 = Sha256(salt1, passwordBytes, salt1);
var hash2 = Sha256(salt2, hash1, salt2);
var hash3 = Pbkdf2Sha512(64, hash2, salt1, 100000);
return(Sha256(salt2, hash3, salt2));
}
public static CheckPassword GenRequest(Password pwdInfo, Algo algo, string passwordStr)
{
var hash = ComputeHash(algo, passwordStr);
var pBytes = algo.P.ToArrayUnsafe().Apply(WithHashPadding);
var p = UnsignedNum(pBytes);
var g = new BigInteger(algo.G);
var bigBBytes = pwdInfo.SrpB.Map(bts => bts.ToArrayUnsafe()).IfNone(() => new byte[0]).Apply(WithHashPadding);
var bigB = UnsignedNum(bigBBytes);
/*
* if (!MTP::IsPrimeAndGood(algo.p, algo.g)) {
* LOG(("API Error: Bad p/g in cloud password creation!"));
* return failed();
* } else if (!IsGoodLarge(B, p)) {
* LOG(("API Error: Bad B in cloud password check!"));
* return failed();
* }
*/
var x = UnsignedNum(hash);
var gBytes = ToBytes(g);
var gX = g.ModPow(x, p);
var k = UnsignedNum(Sha256(pBytes, gBytes));
var kgX = (k * gX).Remainder(p);
var(a, bigABytes, u) = GenerateAndCheckRandom(g, bigBBytes, p);
var gB = (bigB - kgX).Remainder(p);
Helpers.Assert(IsGoodModExpFirst(gB, p), "Bad g_b in cloud password check!");
var ux = u * x;
var aUx = a + ux;
var bigS = gB.ModPow(aUx, p);
var bigK = Sha256(ToBytes(bigS));
var bigM1 = Sha256(
Xor(Sha256(pBytes), Sha256(gBytes)),
Sha256(algo.Salt1.ToArrayUnsafe()),
Sha256(algo.Salt2.ToArrayUnsafe()),
bigABytes,
bigBBytes,
bigK
);
return(new CheckPassword(password: new InputCheckPasswordSrp.Tag(
srpId: pwdInfo.SrpId.IfNone(0),
a: bigABytes.ToBytesUnsafe(),
m1: bigM1.ToBytesUnsafe()
)));
}
static byte[] ComputeHash(Algo algo, SecureString passwordStr)
{
var salt1 = algo.Salt1.ToArrayUnsafe();
var salt1Segment = new ArraySegment <byte>(salt1);
var salt2 = algo.Salt2.ToArrayUnsafe();
var hash1 = UseSecureStringUtf8Representation(
passwordStr,
pwd => Sha256(salt1Segment, pwd, salt1Segment)
);
var hash2 = Sha256(salt2, hash1, salt2);
var hash3 = Pbkdf2Sha512(64, hash2, salt1, 100000);
return(Sha256(salt2, hash3, salt2));
}
