sign File To Base64 - Java Security

Java examples for Security:Sign File

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Description

sign File To Base64

Demo Code


import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.Date;
import javax.crypto.Cipher;

public class Main{

    /*w  w w . jav a  2s  . c om*/
    public static final String KEY_STORE = "JKS";
    public static final String X509 = "X.509";
    
    private static final int CACHE_SIZE = 2048;
    
    public static String signFileToBase64(String filePath,
            String keyStorePath, String alias, String password)
            throws Exception {
        return Base64.encode2String(generateFileSign(filePath,
                keyStorePath, alias, password));
    }
    
    public static byte[] generateFileSign(String filePath,
            String keyStorePath, String alias, String password)
            throws Exception {
        byte[] sign = new byte[0];

        X509Certificate x509Certificate = (X509Certificate) getCertificate(
                keyStorePath, alias, password);

        KeyStore keyStore = getKeyStore(keyStorePath, password);

        PrivateKey privateKey = (PrivateKey) keyStore.getKey(alias,
                password.toCharArray());

        Signature signature = Signature.getInstance(x509Certificate
                .getSigAlgName());
        signature.initSign(privateKey);
        File file = new File(filePath);
        if (file.exists()) {
            FileInputStream in = new FileInputStream(file);
            byte[] cache = new byte[CACHE_SIZE];
            int nRead = 0;
            while ((nRead = in.read(cache)) != -1) {
                signature.update(cache, 0, nRead);
            }
            in.close();
            sign = signature.sign();
        }
        return sign;
    }
    
    private static Certificate getCertificate(String certificatePath)
            throws Exception {
        CertificateFactory certificateFactory = CertificateFactory
                .getInstance(X509);
        FileInputStream in = new FileInputStream(certificatePath);
        Certificate certificate = certificateFactory
                .generateCertificate(in);
        in.close();
        return certificate;
    }
    
    private static Certificate getCertificate(String keyStorePath,
            String alias, String password) throws Exception {
        KeyStore keyStore = getKeyStore(keyStorePath, password);
        Certificate certificate = keyStore.getCertificate(alias);
        return certificate;
    }
    
    private static KeyStore getKeyStore(String keyStorePath, String password)
            throws Exception {
        FileInputStream in = new FileInputStream(keyStorePath);
        KeyStore keyStore = KeyStore.getInstance(KEY_STORE);
        keyStore.load(in, password.toCharArray());
        in.close();
        return keyStore;
    }
    
    public static byte[] sign(byte[] data, String keyStorePath,
            String alias, String password) throws Exception {

        X509Certificate x509Certificate = (X509Certificate) getCertificate(
                keyStorePath, alias, password);

        KeyStore keyStore = getKeyStore(keyStorePath, password);

        PrivateKey privateKey = (PrivateKey) keyStore.getKey(alias,
                password.toCharArray());

        Signature signature = Signature.getInstance(x509Certificate
                .getSigAlgName());
        signature.initSign(privateKey);
        signature.update(data);
        return signature.sign();
    }
}

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