How can i change Hash Algorithm from SHA1 to SHA256 on openPDF 1.4.1

[ngocduy96]

Can I change Hash Algorithm from SHA1 to SHA256 when signing PDF files on openPDF version 1.4.1?
Here is my code:

public void signPdf(String inputPdfPath, String outputPdfPath, String p12FilePath, String p12Password, String reason, String location) throws Exception {
        KeyStore keystore = KeyStore.getInstance("PKCS12");
        try (FileInputStream fis = new FileInputStream(p12FilePath)) {
            keystore.load(fis, p12Password.toCharArray());
        }

        String alias = keystore.aliases().nextElement();
        PrivateKey privateKey = (PrivateKey) keystore.getKey(alias, p12Password.toCharArray());
        Certificate[] certChain = keystore.getCertificateChain(alias);

        PdfReader reader = new PdfReader(inputPdfPath);
        try (FileOutputStream os = new FileOutputStream(outputPdfPath);
             PdfStamper stamper = PdfStamper.createSignature(reader, os, '\0')) {

            PdfSignatureAppearance appearance = stamper.getSignatureAppearance();

            appearance.setReason(reason);
            appearance.setLocation(location);
            appearance.setAcro6Layers(true);

            Rectangle rectangle = new Rectangle(450, 790, 595, 842);

            appearance.setVisibleSignature(rectangle,1);

            PdfWriter writer = stamper.getWriter();
            writer.setEncryption(null, null, PdfWriter.ALLOW_PRINTING, PdfWriter.STANDARD_ENCRYPTION_128);

            appearance.setCrypto(privateKey, certChain, null, PdfSignatureAppearance.WINCER_SIGNED);
        }
    }