รบกวนสอบถามเรื่อง Content signature ใน VB.NET ครับ

private PrivateKey pri;
private PublicKey pub;
private Cipher cipher;

KeyFactory kf = KeyFactory.getInstance("RSA");
byte[] priKeyBytes = Files.readAllBytes(new File("private_key.pem").toPath());
PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(priKeyBytes);

pri = kf.generatePrivate(spec);
byte[] pubKeyBytes = Files.readAllBytes(new File("public_key.pem").toPath());
X509EncodedKeySpec pubSpec = new X509EncodedKeySpec(pubKeyBytes);
pub = kf.generatePublic(pubSpec);


public String createSignature(String message) throws NoSuchAlgorithmException,
SignatureException, IOException, InvalidKeySpecException, InvalidKeyException {
Signature signature = Signature.getInstance("SHA256withRSA");
signature.initSign(pri);
signature.update(message.getBytes());
byte[] signatureBytes = signature.sign();
String encodedSignature = Base64.getEncoder().encodeToString(signatureBytes);
return encodedSignature;
}


public boolean verify(String message, String signature) throws SignatureException,
IOException, NoSuchAlgorithmException, InvalidKeySpecException, InvalidKeyException {
Signature sign = Signature.getInstance("SHA256withRSA");
sign.initVerify(pub);
sign.update(message.getBytes("UTF-8"));
return sign.verify(Base64.getDecoder().decode(signature.getBytes("UTF-8")));
}