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How to sign Pdf hash data using the private key of SafeNet Token in C#

I am trying to sign a remotely generated pdf hash data using the private key from my SafeNet token using c# and .Net core 3.1 framework. I can successfully sign the hash data using the key stored Windows store. When I select the certificate stored in my SafeNet to sign the data, it never prompts the SafeNet token password rather it throws an exception. But I can sign any XML data using the same certificate from Token.
I have checked some other examples and tutorials on the internet which are mainly based on RSA or RSACryptoServiceProvider which can not sign in case of private is non-exportable
Tried case 1: signing works only for the exportable private key
RSA rsa = x509Certificate2.GetRSAPrivateKey(); // or cert.GetRSAPublicKey() when need public key use the key
AsymmetricCipherKeyPair keypair = DotNetUtilities.GetRsaKeyPair(rsa);
// Hash data = hashByteArray
byte[] signedBytes = rsa.SignData(hashByteArray, System.Security.Cryptography.HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
Tried case 2: signing works only for the exportable private key
ICipherParameters Akp = Org.BouncyCastle.Security.DotNetUtilities.GetKeyPair(x509Certificate2.PrivateKey).Private;
IExternalSignature iExternalSignature = new PrivateKeySignature(Akp, "SHA-256");
byte[] extSignature = iExternalSignature.Sign(<data array>);
Tried case 3: works for all keys (exportable or non-exportable) stored in windows store but not works using Smart card key and throws an exception
In my case, the private key is always RSACng.
if (x509Certificate2.PrivateKey is RSACryptoServiceProvider)
{
//never comes here
Log.log("Get the RSACryptoServiceProvider");
}
else if (x509Certificate2.PrivateKey is ECDsaCng)
{
//never comes here
Log.log("Get the ECDsaCng");
}
else if (x509Certificate2.PrivateKey is RSACng)
{
// always comes here
Log.log("HasPrivateKey: " + x509Certificate2.HasPrivateKey.ToString());
byte[] signedBytes = sign(selectedCert, hashByteArray);
return signedBytes;
}
Working Code
public static byte[] sign(X509Certificate2Collection selectedCert, byte[] hashByteArray)
{
X509Certificate2 x509Certificate2 = selectedCert[0];
// Coverting to bouncycastle X509Certificate for sign purpose
ICollection<Org.BouncyCastle.X509.X509Certificate> bouncyCertChains = ConvertX509Cert2ListToBouncyCastleX509CertList(selectedCert);
RSA rsa = (RSA)x509Certificate2.PrivateKey;
(x509Certificate2.PrivateKey as RSACng).Key.SetProperty(
new CngProperty(
"Export Policy",
BitConverter.GetBytes((int)CngExportPolicies.AllowPlaintextExport),
CngPropertyOptions.Persist));
RSAParameters RSAParameters = rsa.ExportParameters(true);
Log.log("Get the GetRsaKeyPair");
AsymmetricCipherKeyPair keypair = DotNetUtilities.GetRsaKeyPair(RSAParameters);
Log.log(keypair.ToString());
IExternalSignature iExternalSignature = new PrivateKeySignature(keypair.Private, DigestAlgorithms.SHA256);
PdfPKCS7 pdfpkcs7 = new PdfPKCS7(null, bouncyCertChains.ToArray(), DigestAlgorithms.SHA256, false);
byte[] computedSh = pdfpkcs7.GetAuthenticatedAttributeBytes(hashByteArray, PdfSigner.CryptoStandard.CMS, null, null);
Log.log("calculated SH: " + System.Convert.ToBase64String(computedSh));
byte[] extSignature = iExternalSignature.Sign(computedSh);
pdfpkcs7.SetExternalDigest(extSignature, null, iExternalSignature.GetEncryptionAlgorithm());
byte[] signedBytes = pdfpkcs7.GetEncodedPKCS7(hashByteArray, null, null, null, PdfSigner.CryptoStandard.CMS);
return signedBytes;
}
Exception message for SmartCard Token:
Internal.Cryptography.CryptoThrowHelper+WindowsCryptographicException: Key not valid for use in specified state.
XML Signing: works perfectly for any certificate
SignedXml doc= new SignedXml(xmlDocument);
doc.SigningKey = x509Certificate2.PrivateKey;
doc.ComputeSignature();
Now, my question is why it does not work for SmartCard Token? What am I missing here?

HttpClient - The message received was unexpected or badly formatted

I am trying to connect to an API that requires two way SSL configured. I have the the certificate and the private key which I configured in postman as shown in the below image.
This works fine in Postman, but SSL fails when I try to implement it in C# using HttpClient. The error that I get is "The message received was unexpected or badly formatted.". I believe it has something to do with incorrect configuration.
I have referred this StackOverflow post to implement my code: Associate a private key with the X509Certificate2 class in .net
Below is what I have tried:
byte[] publicCertificateBytes = File.ReadAllBytes("<Public Certificate>");
var publicCertificate = new X509Certificate2(publicCertificateBytes);
byte[] privateKey = Convert.FromBase64String(File.ReadAllText("<private key file>").Replace("-----BEGIN PRIVATE KEY-----", "").Replace("-----END PRIVATE KEY-----", ""));
using (var rsa = RSA.Create())
{
rsa.ImportPkcs8PrivateKey(privateKey, out _);
publicCertificate = publicCertificate.CopyWithPrivateKey(rsa);
publicCertificate = new X509Certificate2(publicCertificate.Export(X509ContentType.Pkcs12));
}
var httpService = new GenericUtilityManager().ResolveUtility<IHttpService>();
var handler = new HttpClientHandler();
handler.SslProtocols = SslProtocols.Tls12;
handler.ClientCertificateOptions = ClientCertificateOption.Manual;
handler.ClientCertificates.Add(publicCertificate);
handler.ServerCertificateCustomValidationCallback = (sender, cert, chain, sslPolicyErrors) => true;
httpService.InitializeHttpClientHandler(handler);
Please help.

Try to load the certicate using the CreateFromPem static function, this method returns a new certificate with the private key.
var certificateCrt = File.ReadAllText("<Public Certificate>");
var privateKey = File.ReadAllText("<private key file>");
using var certificate = X509Certificate2.CreateFromPem(certificateCrt, privateKey);
If that doesn't work, try to creating a .pfx certificate using OpenSSL:
openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt
I had this problem when I needed to use a certificate on a Windows OS, to work I had to create a .pfx certificate, but on other OS like Mac and Linux it worked fine without a .pfx certificate.

Creating PKCS#7 with ECDSA

I am creating PKCS#7 Message:
SignedCms signedCms = new SignedCms(GetContent());
var certificateFromFile = new X509Certificate2("my-ecdsa.pfx");
var signer = new CmsSigner(certificateFromFile);
signer.DigestAlgorithm = new Oid("2.16.840.1.101.3.4.2.1"); //sha256
// Sign the message.
signedCms.ComputeSignature(signer);
// Encode the message.
var myCmsMessage = signedCms.Encode();
But there is exception thrown at signedCms.ComputeSignature():
Invalid provider type specified
When using pfx with RSA key, everything works as expected.
Is ECDSA not supported? Can I change provider?
My cert info:
Signing algorithm: sha256RCDSA
Public key: ECC (256 bits)
Public key parameters: secP256k1

Unable to fetch private key from .net x509certificate2 object to bouncycastle AsymmetricCipherKeyPair

I was trying to get keypair for pkcs-7 signature an X509Certificate2 object from this code.
RSACryptoServiceProvider key = (RSACryptoServiceProvider)Cert.PrivateKey;
RSAParameters rsaparam = key.ExportParameters(true);
AsymmetricCipherKeyPair keypair = DotNetUtilities.GetRsaKeyPair(rsaparam);
This works fine if X509Certificate2 object is created using .pfx file like this
X509Certificate2 cert = new X509Certificate2(".pfx file path", "password");
it works fine.
but when the certificate is listed from certificate store like this
X509Certificate2 cert;
X509Store UserCertificateStore = new X509Store("My");
UserCertificateStore.Open(OpenFlags.ReadOnly);
var certificates = UserCertificateStore.Certificates;
foreach (var certificate in certificates)
{
if (certificate.Thumbprint==thumbprint)
{
cert=certificate;
break;
}
}
it throws an exception with the message - Key not valid for use in specified state.
after #Crypt32 answer tried using RSA method sign hash
RSACryptoServiceProvider csp = (RSACryptoServiceProvider)cert.PrivateKey;
using (SHA256Managed sHA256 = new SHA256Managed())
{
byte[] hash = sHA256.ComputeHash(data);
return csp.SignHash(hash, CryptoConfig.MapNameToOID("SHA256"));
}
but the signature was not in PKCS#7 format

This is because BouncyCastle attempts to get raw key material (literally, export) from .NET object while actual key is not marked as exportable. In Windows systems, keys are stored in cryptographic service providers which control all key operations. When you need to perform a specific cryptographic operation, you are asking CSP to do a job and it does without having to expose key material to you. If the key was imported/generated in CSP as exportable, you can ask CSP to export key material. If this flag was not set, CSP won't give you the key.
I don't know how BouncyCastle works, but if it expects raw key material, then you need exportable private key in your certificate.

To answer the underlying question, "How do I make a PKCS#7 SignedData message signed with RSA+SHA-2-256?"
https://github.com/Microsoft/dotnet/blob/master/releases/net471/dotnet471-changes.md#bcl says that SHA-2-256 not only works in 4.7.1, but it's the default now:
Updated SignedXML and SignedCMS to use SHA256 as a default over SHA1. SHA1 may still be used by selected as a default by enabling a context switch. [397307, System.Security.dll, Bug]
On older frameworks it's possible via:
ContentInfo content = new ContentInfo(data);
SignedCms cms = new SignedCms(content);
CmsSigner signer = new CmsSigner(cert);
signer.DigestAlgorithm = new Oid("2.16.840.1.101.3.4.2.1");
cms.ComputeSignature(signer);
return cms.Encode();
Where "2.16.840.1.101.3.4.2.1" is OID-ese for SHA-2-256.

How can i import RSACryptoServiceProvider private key to bouncy castle

Currently, I am using the etoken (safenet), bouncy castle library and X509certificate2 to decrypt a p7m file.
I would like to decrypt the p7m byteArray through the Bouncy Castle library using a X509Ceritificate2 private key. I can retrieve the X509Ceritificate2 private key from the X509Store and the key is not null. I can utilize the private key when it is a RSACryptoServiceProvider object.
RSACryptoServiceProvider systemUserOnlyReadablePrivateKey = certificate.PrivateKey as RSACryptoServiceProvider;
However, when I tried to tranform the private key from RSACryptoServiceProvider object to other objects such as byte[] or AsymetricKeyParameter, An exception message "key not valid for use in specified state." has been shown.
AsymetricKeyParameter key = DotNetUtilities.GetKeyPair(cert.Privat‌​eKey).Private; //Exception prompt
Since the certificates are stored in the eToken and automatically added in the X509Store when eToken plugin into computer and certificates removed when the eToken plugged out, I can not set the certificates as exportable.
Does Bouncy Castle API support decryption by using X509Ceritificate2 private key?
How can I transform the key into other object so that I can decrypt by the Bouncy Castle API.
Thanks.
The following is my source code.
byte[] p7mByte = p7mByteArray; //p7m to byte array
cmsEnvelopedData = new CmsEnvelopedDataParser(p7mByteArray);
RecipientInformationStore recipientInformationStore = cmsEnvelopedData.GetRecipientInfos();
RecipientInformation recipientInformation = null;
X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
store.Open(OpenFlags.MaxAllowed);
var certificates = store.Certificates;
foreach (var certificate in certificates)
{
if (certificate.PrivateKey != null)
{
RecipientID recipientId = new RecipientID();
recipientId.SerialNumber = certificate.SerialNumber;
recipientId.Issuer = certificate.IssuerDN;
recipientInformation = recipientInformationStore.GetFirstRecipient(recipientId);
RSACryptoServiceProvider systemUserOnlyReadablePrivateKey = certificate.PrivateKey as RSACryptoServiceProvider;
CspParameters cspParameters = new CspParameters(systemUserOnlyReadablePrivateKey.CspKeyContainerInfo.ProviderType, systemUserOnlyReadablePrivateKey.CspKeyContainerInfo.ProviderName, systemUserOnlyReadablePrivateKey.CspKeyContainerInfo.KeyContainerName)
{
Flags = CspProviderFlags.UseArchivableKey
};
RSACryptoServiceProvider csp = new RSACryptoServiceProvider(cspParameters);
csp = (RSACryptoServiceProvider)certificate.PrivateKey;
CmsTypedStream recData = null;
recData = recipientInformation.GetContentStream(DotNetUtilities.GetKeyPair(cert.Privat‌​eKey).Private); //Exception prompt
}
}