Recently, I have done a project, in which I need to use an RSASSA-PSS-2048-SHA256 algorithm to sign the data sent. I found many on the Internet, but I didn't find the right one. Now, I'm almost done, so I want to sort this out. I'm a rookie. If there is anything wrong in the document, please help me to point out. Thank you

All right, no more nonsense, just go to the code

/**
     * SHA256WithRSA autograph
     *
     * @param data
     * @return
     * @throws Exception
     */
    public static String sign256(String data, String privateKeyStr) throws Exception {

        PrivateKey privateKey = loadPrivateKey(privateKeyStr);
        Signature signature = Signature.getInstance("SHA256WithRSA/PSS", new BouncyCastleProvider());

        signature.initSign(privateKey);

        signature.update(data.getBytes("UTF-8"));
        return new String(Base64.encode(signature.sign(), Base64.NO_WRAP));


    }

/**
     * Load private key from string < br >
     * PKCS8EncodedKeySpec (PKCs × 8 encoded Key instruction) is used when loading.
     *
     * @return
     * @throws Exception
     */
    public static PrivateKey loadPrivateKey(String private_key) throws Exception {

        try {
            byte[] buffer = Base64.decode(private_key, 0);

            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);

            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);

        } catch (NoSuchAlgorithmException e) {
            throw new Exception("No algorithm is available.");
        } catch (InvalidKeySpecException e) {
            throw new Exception("Private key illegal");
        } catch (NullPointerException e) {
            throw new Exception("Private key data is empty");
        }
    }

It didn't work because

Signature signature = Signature.getInstance("SHA256withRSA/PSS","BC"); this line of code may have incorrect parameters 

After a lot of investigation, it was changed to

Signature signature = Signature.getInstance("SHA256WithRSA/PSS", new BouncyCastleProvider()); then the verification is passed

The BouncyCastleProvider() class is in a bcprov-ext-jdk15on-158.jar (this jar can be downloaded after baidu searches)

Maybe it's different from other people's problems. I only record my problems here. Don't spray if you don't like it. Thank you