encrypt By Private Key - Java Security

Java examples for Security:Key

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Description

encrypt By Private Key

Demo Code


//package com.java2s;

import java.io.ByteArrayOutputStream;

import java.io.FileInputStream;

import java.security.KeyStore;
import java.security.PrivateKey;

import javax.crypto.Cipher;

public class Main {


    public static final String KEY_STORE = "JKS";

    private static final int MAX_ENCRYPT_BLOCK = 117;

    public static byte[] encryptByPrivateKey(byte[] data,
            String keyStorePath, String alias, String password)
            throws Exception {

        PrivateKey privateKey = getPrivateKey(keyStorePath, alias, password);
        Cipher cipher = Cipher.getInstance(privateKey.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;

        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }/*from  w ww . jav a 2s.  c  o m*/
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    private static PrivateKey getPrivateKey(String keyStorePath,
            String alias, String password) throws Exception {
        KeyStore keyStore = getKeyStore(keyStorePath, password);
        PrivateKey privateKey = (PrivateKey) keyStore.getKey(alias,
                password.toCharArray());
        return privateKey;
    }

    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;
    }
}

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