[Java] How to retrieve the certificate and the private key from the KeyStore.

GetCertificateAndKeyFromKeyStore.java

/*
 * The following snippet retrieves, from an already loaded keystore, the certificate and the
 * private key used to sign the requests. It takes as assumption that the keystore contains
 * only one certificate.
 *
 * Gists provided for illustrative purposes only. Developers can use these as a support tool
 * but the Office of the Revenue Commissioners (Revenue) does not provide any warranty with 
 * these gists.
 */
public void getCertificateAndKeyFromKeyStore(KeyStore keyStore, String encodedPassword) throws KeyStoreException, UnrecoverableEntryException, NoSuchAlgorithmException {

    // Retrieving the certificate.
    String certificateAlias = keyStore.aliases().nextElement();
    X509Certificate certificate = (X509Certificate)keyStore.getCertificate(certificateAlias);

    // Retrieving the private key.
    KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry)keyStore.getEntry(
        certificateAlias,
        new KeyStore.PasswordProtection(encodedPassword.toCharArray())
    );
    PrivateKey privateKey = privateKeyEntry.getPrivateKey();
}