FIRM PKCS # 1 RSA Sha256WithRsa

I need to sign a chain to send to a financial institution by means of a WebService .

The steps are the following:

Procedure to generate the value of the signature parameter

Sample guide document

a. The following original string of the query message is generated

|14/12/2016 18:01:08|operador0125|ABCD1234567F8|fisica|

b. The original string of the query message is followed by steps 2 and 3 of the signature process described in section 3, from which the following string is obtained:

Htu1kKxYUPLKSDDYZ0g2lR0qH5grAOwuW3RRyCTXuJU68jD170hCmNg8m7SGgrIWh07YkRlnhcZs6zwwiHpPSCQtVKLgkMsZ0Q0ENZ9h2/M88ZiNDTrUQft/WGlNsvNKNbb5oOZQ4lM/mCvTl3Zdy7A40kpS54QqMUIEdyWkVpibriHAsuWv8KZHQBvSYm2rZ0rJBEuGs7I2IMWxgCy9yHh7ub7dyqmzWmtQL87HC7yEPgLPnNFXyj53ylS2Pv/B0tgdHfmvx3lyZ2BDJdN0ImW2JXwMlNOhzLvQF80JsJSIeNH+m5JUrjA2Ntfb3/m71obg9tfAuwU7NsPZoSJ2pg==

00000100000100012095.cer

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AES-128-CBC,041BEED517ABF2499A0A70247B392DC3

RA3VnZHkktMcBpCa7u0+j1l56CRoKezQwMWdrU0Nevj3y0Ff+VFsuFKPDyoTmN45
60okZEazBwI+jPF3sLbHvuQMPE2pUTrU0Y1x6cjnTMqg9FKxo/o3Za64KjIkbGde
............................................... más contenido...
-----END RSA PRIVATE KEY-----

123_XXXXXXXXXX

What I have researched, to generate a signature ( PKCS ) # 1, with Sha256WithRSA , and in the end It should be passed to Base64 , of all the files, I only need the .cer , which is where I get the public key, and I only have to encrypt the original string, it is correct, but every time I execute the code it generates a different result. Is that normal?

My code is as follows:

byte[] encodedBytes;


String encodedBytesStr;
System.out.println("firmaCompuesta: " + firmaCompuesta);
try {
    boolean useBouncyCastleProvider = true;

    Provider provider = null;
    if (useBouncyCastleProvider) {
        provider = new BouncyCastleProvider();
        Security.addProvider(provider);
    }

    // Message Digest
    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());

    FileInputStream fin = new FileInputStream(FILENAME_CER);
    CertificateFactory f = CertificateFactory.getInstance("X.509");
    X509Certificate certificate = (X509Certificate) f.generateCertificate(fin);
    PublicKey publickey = certificate.getPublicKey();

    String hashingAlgorithm = "SHA-256";

    MessageDigest messageDigestProvider = null;
    if (null != provider) {
        messageDigestProvider = MessageDigest.getInstance(hashingAlgorithm, provider);
    } else {
        messageDigestProvider = MessageDigest.getInstance(hashingAlgorithm);
    }
    messageDigestProvider.update(firmaCompuesta.getBytes());

    byte[] hash = messageDigestProvider.digest();

    DigestAlgorithmIdentifierFinder hashAlgorithmFinder = new DefaultDigestAlgorithmIdentifierFinder();
    AlgorithmIdentifier hashingAlgorithmIdentifier = hashAlgorithmFinder.find(hashingAlgorithm);

    DigestInfo digestInfo = new DigestInfo(hashingAlgorithmIdentifier, hash);
    byte[] hashToEncrypt = digestInfo.getEncoded();

    // Crypto
    // You could also use "RSA/ECB/PKCS1Padding" for both the BC and SUN Providers.
    Cipher encCipher = null;
    if (null != provider) {
        encCipher = Cipher.getInstance("RSA/NONE/PKCS1Padding", provider);
    } else {
        encCipher = Cipher.getInstance("RSA");
    }

    //=============== JEMJ CIFRADO DESDE .CER =============
    encCipher.init(Cipher.ENCRYPT_MODE, publickey);

    byte[] encrypted = encCipher.doFinal(hashToEncrypt);

    System.out.println("\n\nHash and Encryption Output : \n\n");
    //
    encodedBytes = Base64.encodeBase64(encrypted);
    encodedBytesStr = new String(encodedBytes);
    //
    System.out.println(encodedBytesStr);