(Mono C#) Duplicate Java Verify RSA Signature

Demonstrates how to duplicate a snippet of Java code that verifies an RSA signature.

Chilkat .NET Downloads Chilkat .NET Assemblies Chilkat for .NET Core Chilkat for Mono

// This requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example duplicates the following Java code:

// import com.sun.org.apache.xml.internal.security.utils.Base64;  
// import java.io.ByteArrayInputStream;  
// import java.security.PublicKey;  
// import java.security.Signature;  
// import java.security.cert.CertificateFactory;  
// import java.security.cert.X509Certificate;  
// public class validateSazetak {  
//   public static void main(String[] args) {  
//   String signatureAlgorithm = "SHA256withRSA";  
//   String base64DataToBeSigned = "Hlp...LE4=";  
//   String base64Certificate = "MII...TlQ==";  
//   String base64Signature = "I00...pZA==";  
//   try {  
//       CertificateFactory cf;  
//       X509Certificate certificate = null;  
//       cf = CertificateFactory.getInstance("X.509");  
//       certificate = (X509Certificate) cf.generateCertificate(new 
//       ByteArrayInputStream(Base64.decode(base64Certificate)));  
//        
//       Signature signature = Signature.getInstance(signatureAlgorithm, "SunRsaSign");  
//       PublicKey pk = (PublicKey) certificate.getPublicKey();  
//       signature.initVerify(pk);  
//        
//       byte[] hashBytes = Base64.decode(base64DataToBeSigned);  
//       signature.update(hashBytes);  
//        
//       byte[] sigBytes = Base64.decode(base64Signature);  
//       boolean validity = signature.verify(sigBytes);  
//       System.out.println("Is valid signature:" + validity);  
//     } catch (Exception e) {  
//         System.out.println(e);  
//     }  
// } 

string base64DataToBeSigned = "Hlp...LE4=";
string base64Certificate = "MII...TlQ==";
string base64Signature = "I00...pZA==";

Chilkat.Cert cert = new Chilkat.Cert();
bool success = cert.LoadFromBase64(base64Certificate);
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

Chilkat.Rsa rsa = new Chilkat.Rsa();

success = rsa.SetX509Cert(cert,false);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

rsa.EncodingMode = "base64";
success = rsa.VerifyStringENC(base64DataToBeSigned,"sha256",base64Signature);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

Debug.WriteLine("Signature verified.");