So below you'll find my code that creates a self signed certificate with the private key in there. It's stored in the user store. Now when I use the mmc tool I can just export the private key from the certificate? I thought that was a flag you had to explicitly add when you create the cert?
So what I wanna know is, how do I change this code so that the private key is no longer exportable through mmc.
Code:
public static X509Certificate2 GenerateSelfSignedCertificateNoCA(string subjectName, string issuerName)
{
const int keyStrength = 2048;
// Generating Random Numbers
CryptoApiRandomGenerator randomGenerator = new CryptoApiRandomGenerator();
SecureRandom random = new SecureRandom(randomGenerator);
// The Certificate Generator
X509V3CertificateGenerator certificateGenerator = new X509V3CertificateGenerator();
// Serial Number
BigInteger serialNumber = BigIntegers.CreateRandomInRange(BigInteger.One, BigInteger.ValueOf(Int64.MaxValue), random);
certificateGenerator.SetSerialNumber(serialNumber);
// Signature Algorithm
const string signatureAlgorithm = "SHA256WithRSA";
certificateGenerator.SetSignatureAlgorithm(signatureAlgorithm);
// Issuer and Subject Name
X509Name subjectDN = new X509Name(subjectName);
X509Name issuerDN = new X509Name(issuerName);
certificateGenerator.SetIssuerDN(issuerDN);
certificateGenerator.SetSubjectDN(subjectDN);
// Valid For
DateTime notBefore = DateTime.UtcNow.Date;
DateTime notAfter = notBefore.AddYears(2);
certificateGenerator.SetNotBefore(notBefore);
certificateGenerator.SetNotAfter(notAfter);
// Subject Public Key
AsymmetricCipherKeyPair subjectKeyPair;
var keyGenerationParameters = new KeyGenerationParameters(random, keyStrength);
var keyPairGenerator = new RsaKeyPairGenerator();
keyPairGenerator.Init(keyGenerationParameters);
subjectKeyPair = keyPairGenerator.GenerateKeyPair();
certificateGenerator.SetPublicKey(subjectKeyPair.Public);
// Generating the Certificate
AsymmetricCipherKeyPair issuerKeyPair = subjectKeyPair;
// selfsign certificate
Org.BouncyCastle.X509.X509Certificate certificate = certificateGenerator.Generate(subjectKeyPair.Private, random);
// correcponding private key
PrivateKeyInfo info = PrivateKeyInfoFactory.CreatePrivateKeyInfo(subjectKeyPair.Private);
// merge into X509Certificate2
X509Certificate2 x509 = new System.Security.Cryptography.X509Certificates.X509Certificate2(certificate.GetEncoded());
Asn1Sequence seq = (Asn1Sequence)Asn1Object.FromByteArray(info.PrivateKey.GetDerEncoded());
if (seq.Count != 9)
{
//throw new PemException("malformed sequence in RSA private key");
}
RsaPrivateKeyStructure rsa = new RsaPrivateKeyStructure(seq);
RsaPrivateCrtKeyParameters rsaparams = new RsaPrivateCrtKeyParameters(
rsa.Modulus, rsa.PublicExponent, rsa.PrivateExponent, rsa.Prime1, rsa.Prime2, rsa.Exponent1, rsa.Exponent2, rsa.Coefficient);
x509.PrivateKey = DotNetUtilities.ToRSA(rsaparams);
// Console.Write("Private key: " + x509.PrivateKey);
return x509;
}
DotNetUtilities.ToRSA will always set the private key to Exportable. To prevent this, there is an alternate way to convert your BouncyCastle key to a .NET X509Certificate2 as taken from here
public X509Certificate2 GenerateSelfSignedCertificateNoCA(string subjectName, string issuerName)
{
const int keyStrength = 2048;
// Generating Random Numbers
CryptoApiRandomGenerator randomGenerator = new CryptoApiRandomGenerator();
SecureRandom random = new SecureRandom(randomGenerator);
// The Certificate Generator
X509V3CertificateGenerator certificateGenerator = new X509V3CertificateGenerator();
// Serial Number
BigInteger serialNumber = BigIntegers.CreateRandomInRange(BigInteger.One, BigInteger.ValueOf(Int64.MaxValue), random);
certificateGenerator.SetSerialNumber(serialNumber);
// Signature Algorithm
const string signatureAlgorithm = "SHA256WithRSA";
certificateGenerator.SetSignatureAlgorithm(signatureAlgorithm);
// Issuer and Subject Name
X509Name subjectDN = new X509Name(subjectName);
X509Name issuerDN = new X509Name(issuerName);
certificateGenerator.SetIssuerDN(issuerDN);
certificateGenerator.SetSubjectDN(subjectDN);
// Valid For
DateTime notBefore = DateTime.UtcNow.Date;
DateTime notAfter = notBefore.AddYears(2);
certificateGenerator.SetNotBefore(notBefore);
certificateGenerator.SetNotAfter(notAfter);
// Subject Public Key
AsymmetricCipherKeyPair subjectKeyPair;
var keyGenerationParameters = new KeyGenerationParameters(random, keyStrength);
var keyPairGenerator = new RsaKeyPairGenerator();
keyPairGenerator.Init(keyGenerationParameters);
subjectKeyPair = keyPairGenerator.GenerateKeyPair();
certificateGenerator.SetPublicKey(subjectKeyPair.Public);
// Generating the Certificate
AsymmetricCipherKeyPair issuerKeyPair = subjectKeyPair;
// selfsign certificate
Org.BouncyCastle.X509.X509Certificate certificate = certificateGenerator.Generate(subjectKeyPair.Private, random);
//import into store
var certificateEntry = new X509CertificateEntry(certificate);
string friendlyName = certificate.SubjectDN.ToString();
var store = new Pkcs12Store();
store.SetCertificateEntry(friendlyName, certificateEntry);
store.SetKeyEntry(friendlyName, new AsymmetricKeyEntry(subjectKeyPair.Private), new[] {certificateEntry});
//save to memorystream
var password = "password";
var stream = new MemoryStream();
store.Save(stream, password.ToCharArray(), random);
// convert into X509Certificate2
X509Certificate2 x509 = new System.Security.Cryptography.X509Certificates.X509Certificate2(stream.ToArray(), password, X509KeyStorageFlags.UserKeySet);
return x509;
}
The private key is now marked as Exportable=false.