/// <summary>
/// Second part of 2FA.
/// </summary>
/// <param name="user">User information.</param>
/// <param name="certificate">User <see cref="X509Certificate2"/> public certificate in raw form.</param>
/// <param name="usersDb">Enigma's user database.</param>
/// <param name="crlListPath">Path on FS to CRL directory.</param>
/// <param name="caTrustListPath">Path on FS to CA trust list.</param>
public void LoginPartTwo(User user, byte[] certificate, UserDatabase usersDb, string crlListPath, string caTrustListPath)
{
var userCert = new X509Certificate2(certificate);
var publicKeyFromCertificate = ((RSACryptoServiceProvider)userCert.PublicKey.Key).ExportParameters(false);
// compare user public RSA key from x509 public certificate with a public RSA key that was stored when user first registered
if (!RsaAlgorithm.CompareKeys(publicKeyFromCertificate, RsaAlgorithm.ExportParametersFromXmlString(user.PublicKey, false)))
{
throw new Exception("Wrong certificate used.");
}
// if wrong file is loaded instead of the x509 public certificate in PEM format
if (userCert == null)
{
throw new Exception("Certificate error.");
}
// update user last login time and reset atttemp count
usersDb.UpdateLoginTime(user, DateTime.Now.ToString("dddd, MMM dd yyyy, hh:mm:ss"));
// reset login attempt if necessary
if (user.LoginAttempt != 0)
{
usersDb.ResetLoginAttempts(user);
}
//if (CertificateValidator.VerifyCertificate(userCert, out var errorMsg, false) == false)
//{
// throw new Exception(errorMsg);
//}
// Check if the certificate has been revoked and set Revoked value if necessary.
if (CertificateValidator.VerifyCertificateRevocationStatus(userCert, crlListPath, caTrustListPath))
{
usersDb.SetCertificateRevokeStatus(user);
//throw new Exception("Certificate has been revoked.");
}
}
/// <summary>
/// Registers a new user if the register policy are met.
/// </summary>
/// <param name="username">Users account username.</param>
/// <param name="password">Users password.</param>
/// <param name="certificateFilePath">Path on FS to users certificate.</param>
public void Register(ref string username, string password, string certificateFilePath, bool skipPasswordStrengthCheck = false)
{
if (username.Length > 25)
{
throw new Exception("Usernames can't have more than 25 characters.");
}
if (!skipPasswordStrengthCheck && password.Contains(username))
{
throw new Exception("Password cannot contain your username.");
}
// Probability of repetition of this do-while loop is low.
do
{
// Add a random 4-digit number to users username.
var csprng = new SecureRandom(new DigestRandomGenerator(new Sha256Digest()));
csprng.SetSeed(DateTime.Now.Ticks); // TODO: is this a good seed value?
var suffix = "#" + csprng.Next(1_000, 9_999).ToString();
// If username collision occurs, generate new 4-digit suffix.
if (data.GetUser(username + suffix) != null)
{
continue;
}
else
{
username += suffix;
break;
}
} while (true);
// Check if a password used some of the most common passwords discovered in various data breaches.
if (!skipPasswordStrengthCheck && PasswordAdvisor.CommonPasswordCheck(password, commonPasswordsPath))
{
throw new Exception("This password is not allowed. Please try again.");
}
// Check password strength.
if (!skipPasswordStrengthCheck && !PasswordAdvisor.IsPasswordStrong(password, out var passwordStrength, false))
{
throw new Exception($"Password is deemed {passwordStrength}. Please try again.");
}
var cert = new X509Certificate2(certificateFilePath);
// Check if key length is >= 2048 bits.
if (CertificateValidator.VerifyCertificateKeyLength(cert) == false)
{
throw new Exception("Key length has to be at least 2048 bits.");
}
// Checks if the certificate has expired and if it is issued by a proper root certificate.
if (CertificateValidator.VerifyCertificate(cert, caTrustListPath, out var errorMsg, true) == false)
{
throw new Exception(errorMsg);
}
// Check if the certificate is revoked.
if (CertificateValidator.VerifyCertificateRevocationStatus(cert, crlListPath, caTrustListPath) == true)
{
throw new Exception("Certificate has been revoked.");
}
// Check if certificate has a proper key usage set.
if (CertificateValidator.VerifyKeyUsage(cert) == false)
{
throw new Exception("Certificate must have 'digitalSignature' and 'keyEncipherment' set as it's key usage.");
}
}