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package com.xkl.tools;
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/**
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* Created by zhaoyue on 2017/3/13.
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*/
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import java.math.BigInteger;
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import java.security.KeyFactory;
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import java.security.KeyPair;
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import java.security.KeyPairGenerator;
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import java.security.NoSuchAlgorithmException;
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import java.security.interfaces.RSAPrivateKey;
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import java.security.interfaces.RSAPublicKey;
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import java.security.spec.RSAPrivateKeySpec;
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import java.security.spec.RSAPublicKeySpec;
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import java.util.HashMap;
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import javax.crypto.Cipher;
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public class RSATools {
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public static void main(String[] args) throws Exception {
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// TODO Auto-generated method stub
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HashMap<String, Object> map = RSATools.getKeys();
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//生成公钥和私钥
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RSAPublicKey publicKey = (RSAPublicKey) map.get("public");
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RSAPrivateKey privateKey = (RSAPrivateKey) map.get("private");
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//模
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String modulus = publicKey.getModulus().toString();
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//公钥指数
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String public_exponent = publicKey.getPublicExponent().toString();
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//私钥指数
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String private_exponent = privateKey.getPrivateExponent().toString();
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//明文
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String ming = "123456789";
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//使用模和指数生成公钥和私钥
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RSAPublicKey pubKey = RSATools.getPublicKey(modulus, public_exponent);
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RSAPrivateKey priKey = RSATools.getPrivateKey(modulus, private_exponent);
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//加密后的密文
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String mi = RSATools.encryptByPublicKey(ming, pubKey);
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System.err.println(mi);
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//解密后的明文
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ming = RSATools.decryptByPrivateKey(mi, priKey);
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System.err.println(ming);
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}
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/**
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* 生成公钥和私钥
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*
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* @throws NoSuchAlgorithmException
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*/
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public static HashMap<String, Object> getKeys() throws NoSuchAlgorithmException {
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HashMap<String, Object> map = new HashMap<String, Object>();
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KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
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keyPairGen.initialize(1024);
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KeyPair keyPair = keyPairGen.generateKeyPair();
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RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
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RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
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map.put("public", publicKey);
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map.put("private", privateKey);
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return map;
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}
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/**
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* 使用模和指数生成RSA公钥
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* 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA
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* /None/NoPadding】
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*
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* @param modulus 模
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* @param exponent 指数
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* @return
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*/
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public static RSAPublicKey getPublicKey(String modulus, String exponent) {
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try {
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BigInteger b1 = new BigInteger(modulus);
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BigInteger b2 = new BigInteger(exponent);
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KeyFactory keyFactory = KeyFactory.getInstance("RSA");
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RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);
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return (RSAPublicKey) keyFactory.generatePublic(keySpec);
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} catch (Exception e) {
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e.printStackTrace();
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return null;
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}
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}
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/**
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* 使用模和指数生成RSA私钥
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* 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA
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* /None/NoPadding】
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*
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* @param modulus 模
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* @param exponent 指数
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* @return
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*/
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public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {
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try {
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BigInteger b1 = new BigInteger(modulus);
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BigInteger b2 = new BigInteger(exponent);
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KeyFactory keyFactory = KeyFactory.getInstance("RSA");
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RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2);
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return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
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} catch (Exception e) {
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e.printStackTrace();
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return null;
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}
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}
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/**
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* 公钥加密
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*
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* @param data
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* @param publicKey
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* @return
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* @throws Exception
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*/
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public static String encryptByPublicKey(String data, RSAPublicKey publicKey)
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throws Exception {
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Cipher cipher = Cipher.getInstance("RSA");
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cipher.init(Cipher.ENCRYPT_MODE, publicKey);
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// 模长
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int key_len = publicKey.getModulus().bitLength() / 8;
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// 加密数据长度 <= 模长-11
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String[] datas = splitString(data, key_len - 11);
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String mi = "";
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//如果明文长度大于模长-11则要分组加密
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for (String s : datas) {
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mi += bcd2Str(cipher.doFinal(s.getBytes()));
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}
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return mi;
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}
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/**
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* 私钥解密
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*
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* @param data
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* @param privateKey
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* @return
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* @throws Exception
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*/
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public static String decryptByPrivateKey(String data, RSAPrivateKey privateKey)
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throws Exception {
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Cipher cipher = Cipher.getInstance("RSA");
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cipher.init(Cipher.DECRYPT_MODE, privateKey);
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//模长
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int key_len = privateKey.getModulus().bitLength() / 8;
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byte[] bytes = data.getBytes();
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byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
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System.err.println(bcd.length);
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//如果密文长度大于模长则要分组解密
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String ming = "";
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byte[][] arrays = splitArray(bcd, key_len);
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for (byte[] arr : arrays) {
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ming += new String(cipher.doFinal(arr));
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}
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return ming;
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}
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/**
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* ASCII码转BCD码
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*/
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public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
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byte[] bcd = new byte[asc_len / 2];
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int j = 0;
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for (int i = 0; i < (asc_len + 1) / 2; i++) {
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bcd[i] = asc_to_bcd(ascii[j++]);
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bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
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}
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return bcd;
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}
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public static byte asc_to_bcd(byte asc) {
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byte bcd;
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if ((asc >= '0') && (asc <= '9'))
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bcd = (byte) (asc - '0');
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else if ((asc >= 'A') && (asc <= 'F'))
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bcd = (byte) (asc - 'A' + 10);
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else if ((asc >= 'a') && (asc <= 'f'))
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bcd = (byte) (asc - 'a' + 10);
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else
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bcd = (byte) (asc - 48);
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return bcd;
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}
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/**
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* BCD转字符串
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*/
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public static String bcd2Str(byte[] bytes) {
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char temp[] = new char[bytes.length * 2], val;
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for (int i = 0; i < bytes.length; i++) {
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val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
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temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
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val = (char) (bytes[i] & 0x0f);
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temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
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}
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return new String(temp);
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}
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/**
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* 拆分字符串
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*/
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public static String[] splitString(String string, int len) {
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int x = string.length() / len;
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int y = string.length() % len;
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int z = 0;
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if (y != 0) {
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z = 1;
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}
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String[] strings = new String[x + z];
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String str = "";
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for (int i = 0; i < x + z; i++) {
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if (i == x + z - 1 && y != 0) {
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str = string.substring(i * len, i * len + y);
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} else {
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str = string.substring(i * len, i * len + len);
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}
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strings[i] = str;
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}
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return strings;
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}
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/**
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* 拆分数组
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*/
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public static byte[][] splitArray(byte[] data, int len) {
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int x = data.length / len;
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int y = data.length % len;
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int z = 0;
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if (y != 0) {
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z = 1;
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}
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byte[][] arrays = new byte[x + z][];
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byte[] arr;
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for (int i = 0; i < x + z; i++) {
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arr = new byte[len];
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if (i == x + z - 1 && y != 0) {
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System.arraycopy(data, i * len, arr, 0, y);
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} else {
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System.arraycopy(data, i * len, arr, 0, len);
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}
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arrays[i] = arr;
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}
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return arrays;
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}
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} |
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\ No newline at end of file |
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