(Visual Basic 6.0) RSA SHA256 Signature using Private Key from Java Keystore

Signs plaintext using RSA SHA256 using a key from a Java keystore.

Duplicatest this code:

KeyStore keystore; // key repository for keys containing signature certificate
String alias; // alias for the certificate in the key repository
String password; // password for the certificate's private key
String plaintext; // text being signed


Signature signature = Signature.getInstance("SHA256withRSA");
signature.initSign((PrivateKey) keystore.getKey(alias, password.toCharArray()));
signature.update(plaintext.getBytes("UTF-8"));
byte[] rsa_text= signature.sign();

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

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

Dim jks As New ChilkatJavaKeyStore

Dim jksPassword As String
jksPassword = "secret"

' Load the Java keystore from a file.  The JKS file password is used
' to verify the keyed digest that is found at the very end of the keystore.
' It verifies that the keystore has not been modified.
Dim success As Long
success = jks.LoadFile(jksPassword,"qa_data/jks/sample_secret.jks")
If (success <> 1) Then
    Debug.Print jks.LastErrorText
    Exit Sub
End If

' Get the private key from the JKS.
' The private key password may be different than the file password.
Dim privKeyPassword As String
privKeyPassword = "secret"
Dim caseSensitive As Long
caseSensitive = 0
Dim privKey As PrivateKey
Set privKey = jks.FindPrivateKey(privKeyPassword,"some.alias",caseSensitive)
If (jks.LastMethodSuccess <> 1) Then
    Debug.Print jks.LastErrorText
    Exit Sub
End If

' Establish the RSA object and tell it to use the private key..
Dim rsa As New ChilkatRsa

success = rsa.ImportPrivateKeyObj(privKey)

If (success <> 1) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

' Indicate we'll be signing the utf-8 byte representation of the string..
rsa.Charset = "utf-8"

' Sign some plaintext using RSA-SHA256
Dim binarySignature() As Byte
Dim plaintext As String
plaintext = "this is the text to be signed"
binarySignature = rsa.SignString(plaintext,"SHA256")
If (rsa.LastMethodSuccess <> 1) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

' Alternatively, if the signature is desired in some encoded string form,
' such as base64, base64-url, hex, etc.
rsa.EncodingMode = "base64-url"
Dim signatureStr As String
signatureStr = rsa.SignStringENC(plaintext,"SHA256")
Debug.Print "base64-url RSA signature: " & signatureStr