I appreciate any advice I can on this issue it has been driving me crazy and I cannot find any documentaion. I am currently trying to generate a self-signed root certificate in C# using the mono security api that meets certain requirements (RSA 2048, SHA256, Etc). I have been successfully able to generate a certificate that meets all of these requirements but one.
I am trying to add a CertificatePoliciesExtension these extensions are usually formatted as follows in X509 certs
[4]: ObjectId: 2.5.29.32 Criticality=false
CertificatePolicies [
[CertificatePolicyId: [some policy oid]
[PolicyQualifierInfo:
[qualifierID: some qualifier oid
qualifier: some ascii encoded byte stream]]]]
My Code Is Below:
private void GenerateRootCertMono(RSACryptoServiceProvider rsa, byte[] serialNumber, string password)
{
// default values
string subject = "CN= company name";
string issuer = "CN=company name";
DateTime notBefore = DateTime.Now;
DateTime notAfter = new DateTime(643445675990000000); // 12/31/2039 23:59:59Z
X509CertificateBuilder cb = new X509CertificateBuilder(3);
cb.SerialNumber = serialNumber;
cb.IssuerName = issuer;
cb.NotBefore = notBefore;
cb.NotAfter = notAfter;
cb.SubjectName = subject;
cb.SubjectPublicKey = rsa;
// extensions
BasicConstraintsExtension bce = new BasicConstraintsExtension();
bce.CertificateAuthority = true;
cb.Extensions.Add(bce);
KeyUsageExtension kue = new KeyUsageExtension();
kue.KeyUsage = KeyUsages.digitalSignature ;
KeyUsageExtension kue1 = new KeyUsageExtension();
kue1.KeyUsage = KeyUsages.keyCertSign;
//my failed attempt to generate a simple Certificate Policy Extension
**ASN1 a = new ASN1 ();
a.Add(ASN1Convert.FromOid("2.5.29.32"));
a.Add(ASN1Convert.FromOid("some oid"));
a.Add(new ASN1 (System.Text.Encoding.ASCII.GetBytes("some text")));
CertificatePoliciesExtension pce = new CertificatePoliciesExtension(a);
cb.Extensions.Add(pce);
cb.Extensions.Add(kue);
cb.Extensions.Add(kue1);
// signature
cb.Hash = "SHA256";
byte[] rawcert = cb.Sign(rsa);
X509Certificate2 pfx = new X509Certificate2(rawcert);
pfx.PrivateKey = rsa;
this.PFX = pfx.Export(X509ContentType.Pkcs12, password);
return;
}
I know generating these extensions is possible because I have seen them in other certificates. Does anyone have any experience or advice? I am also flexible with the API if someone knows how to generate theses extensions using MSCAPI in C# for example that would also be an acceptable solution. Thank you in advance for any help.
After scouring multiple sources I was able to solve this problem by switching from Mono to Microsoft's certenroll.dll. My code for generating a self signed certificate with Policy Extensions is below. Hope this helps anyone having similar problems.
Code based off of the following reference: http://technet.microsoft.com/en-us/library/ff182332(v=ws.10).aspx.
public X509Certificate2 CreateSelfSignedCert(string subject,string password,DateTime expDate)
{
// create DN for subject and issuer
var dn = new CX500DistinguishedName();
// dn.Encode("CN=" + subject, X500NameFlags.XCN_CERT_NAME_STR_NONE);
dn.Encode(subject, X500NameFlags.XCN_CERT_NAME_STR_NONE);
// create a new private key for the certificate
CX509PrivateKey privateKey = new CX509PrivateKey();
privateKey.ProviderName = "Microsoft Base Cryptographic Provider v1.0";
privateKey.MachineContext = true;
privateKey.Length = 2048;
privateKey.KeySpec = X509KeySpec.XCN_AT_SIGNATURE; // use is not limited
privateKey.ExportPolicy
= X509PrivateKeyExportFlags.XCN_NCRYPT_ALLOW_PLAINTEXT_EXPORT_FLAG;
privateKey.Create();
// Use Sha256 hashing algorithm
var hashobj = new CObjectId();
hashobj.InitializeFromAlgorithmName(
ObjectIdGroupId.XCN_CRYPT_HASH_ALG_OID_GROUP_ID,
ObjectIdPublicKeyFlags.XCN_CRYPT_OID_INFO_PUBKEY_ANY,
AlgorithmFlags.AlgorithmFlagsNone,
"SHA256");
// Create the self signing request
var cert = new CX509CertificateRequestCertificate();
cert.InitializeFromPrivateKey(
X509CertificateEnrollmentContext.ContextMachine,
privateKey,
string.Empty);
cert.Subject = dn;
cert.Issuer = dn; // the issuer and the subject are the same
cert.NotBefore = DateTime.Now;
cert.NotAfter = expDate;
cert.HashAlgorithm = hashobj;
// extensions
CX509ExtensionKeyUsage ku = new CX509ExtensionKeyUsage();
ku.InitializeEncode(CERTENROLLLib.X509KeyUsageFlags.XCN_CERT_KEY_CERT_SIGN_KEY_USAGE | CERTENROLLLib.X509KeyUsageFlags.XCN_CERT_DIGITAL_SIGNATURE_KEY_USAGE);
ku.Critical = true;
cert.X509Extensions.Add((CX509Extension)ku);
CX509ExtensionBasicConstraints bc = new CX509ExtensionBasicConstraints();
bc.InitializeEncode(true,0);
bc.Critical = false;
cert.X509Extensions.Add((CX509Extension)bc);
// Add the certificate policy.
CObjectId cpOid = new CObjectId();
cpOid.InitializeFromValue("some oid");
CCertificatePolicy cp = new CCertificatePolicy();
CPolicyQualifier Qualifier = new CPolicyQualifier();
Qualifier.InitializeEncode("Policy Notice", PolicyQualifierType.PolicyQualifierTypeUserNotice);
cp.Initialize(cpOid);
cp.PolicyQualifiers.Add(Qualifier);
CCertificatePolicies cps = new CCertificatePolicies();
cps.Add(cp);
CX509ExtensionCertificatePolicies cpExt = new CX509ExtensionCertificatePolicies();
cpExt.InitializeEncode(cps);
cert.X509Extensions.Add((CX509Extension)cpExt);
// Do the final enrollment process
var enroll = new CX509Enrollment();
enroll.InitializeFromRequest(cert); // load the certificate
string csr = enroll.CreateRequest(); // Output the request in base64
// and install it back as the response
enroll.InstallResponse(InstallResponseRestrictionFlags.AllowUntrustedCertificate,
csr, EncodingType.XCN_CRYPT_STRING_BASE64, ""); // no password
// output a base64 encoded PKCS#12 so we can import it back to the .Net security classes
var base64encoded = enroll.CreatePFX( "", PFXExportOptions.PFXExportChainWithRoot);
// instantiate the target class with the PKCS#12 data (and the empty password)
return new System.Security.Cryptography.X509Certificates.X509Certificate2(
System.Convert.FromBase64String(base64encoded), "",
// mark the private key as exportable
System.Security.Cryptography.X509Certificates.X509KeyStorageFlags.Exportable
);
}