(Excel) Duplicate Java Verify RSA Signature

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

Download Excel Class Modules Chilkat Excel Class Modules

' 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);  
'     }  
' } 


base64DataToBeSigned = "Hlp...LE4="

base64Certificate = "MII...TlQ=="

base64Signature = "I00...pZA=="

Dim cert As Chilkat.Cert
Set cert = Chilkat.NewCert

success = cert.LoadFromBase64(base64Certificate)
If (success = False) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

Dim rsa As Chilkat.Rsa
Set rsa = Chilkat.NewRsa

success = rsa.SetX509Cert(cert,False)
If (success = False) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

rsa.EncodingMode = "base64"
success = rsa.VerifyStringENC(base64DataToBeSigned,"sha256",base64Signature)
If (success = False) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

Debug.Print "Signature verified."