C# Non self signed client certs with CERTENROLL.dll are unable to be verified

Question

This is a followup to C# Generate a non self signed client CX509Certificate Request without a CA using the certenroll.dll

I am trying to create a client cert signed by my self signed CA, as in the above question. I can create the desired certs without issue using makecert.exe (they show as trusted). I attempting to do the same in C#. The certs are created and placed in the machine's My store. The self signed CA is also installed in the machine's Trusted store. When I open them, they say:

Windows does not have enough information to verify this certificate.

Help?

Code:

// create DN
var dn = new CX500DistinguishedName();
dn.Encode("CN=Demo Cert", X500NameFlags.XCN_CERT_NAME_STR_NONE);

// create prvate key
var pk = new CX509PrivateKey();
pk.MachineContext = true;
pk.Length = 1024;
pk.KeySpec = X509KeySpec.XCN_AT_KEYEXCHANGE;
pk.ExportPolicy = X509PrivateKeyExportFlags.XCN_NCRYPT_ALLOW_EXPORT_FLAG;
pk.Create();

// use SHA512
var hash = new CObjectId();
hash.InitializeFromAlgorithmName(ObjectIdGroupId.XCN_CRYPT_HASH_ALG_OID_GROUP_ID, ObjectIdPublicKeyFlags.XCN_CRYPT_OID_INFO_PUBKEY_ANY, AlgorithmFlags.AlgorithmFlagsNone, "SHA512");

// EKU
var oid = new CObjectId();
oid.InitializeFromValue("1.3.6.1.5.5.7.3.2");
var oidlist = new CObjectIds();
oidlist.Add(oid);
var eku = new CX509ExtensionEnhancedKeyUsage();
eku.InitializeEncode(oidlist);

// Initialize the signer
var TheCA = GimmeTheCA(); // method returns my self signed CA as X509Certificate2
ISignerCertificate signer = new CSignerCertificate();
signer.Initialize(true, X509PrivateKeyVerify.VerifyNone, EncodingType.XCN_CRYPT_STRING_HEX, TheCA.GetRawCertDataString());

// Root Dn
var Rootdn = new CX500DistinguishedName();
Rootdn.Encode(TheCA.Subject, X500NameFlags.XCN_CERT_NAME_STR_NONE);

// Cert Request
var cert = new CX509CertificateRequestCertificate();
cert.InitializeFromPrivateKey(X509CertificateEnrollmentContext.ContextMachine, pk, "");
cert.Subject = dn;
cert.Issuer = Rootdn;
cert.SignerCertificate = (CSignerCertificate)signer;
cert.NotBefore = DateTime.Now;
cert.NotAfter = new DateTime(2020, 1, 1);
cert.X509Extensions.Add((CX509Extension)eku);
cert.HashAlgorithm = hash;
cert.Encode();

// Enrollment
var enroll = new CX509Enrollment();
enroll.InitializeFromRequest(cert);
enroll.CertificateFriendlyName = "Intel IPT";
string csr = enroll.CreateRequest();

// Install
enroll.InstallResponse(InstallResponseRestrictionFlags.AllowUntrustedRoot, csr, EncodingType.XCN_CRYPT_STRING_BASE64, "");

Answer 1

You may try :

• pk.KeySpec = X509KeySpec.XCN_AT_SIGNATURE;

• pk.KeyUsage = X509PrivateKeyUsageFlags.XCN_NCRYPT_ALLOW_ALL_USAGES;

• Run the application with Elevated Privileges (run it as an Administrator).

• Put a Copy of the CA certificate int the "Computer\Personal" ("MY") Store (but keep the original certificate in the "Computer\Trusted Root Cert. Auth." ("Root") Store)