java实现RSA加密和解密，javarsa加密,RSAUtils.jav

java实现RSA加密和解密，javarsa加密,RSAUtils.jav

RSAUtils.java```javapackage yyy.test.rsa;

import java.math.BigInteger;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.NoSuchAlgorithmException;import java.security.interfaces.RSAPrivateKey;import java.security.interfaces.RSAPublicKey;import java.security.spec.RSAPrivateKeySpec;import java.security.spec.RSAPublicKeySpec;import java.util.HashMap;

import javax.crypto.Cipher;

public class RSAUtils {

/** * 生成公钥和私钥 * @throws NoSuchAlgorithmException  * */public static HashMap<String, Object> getKeys() throws NoSuchAlgorithmException{    HashMap<String, Object> map = new HashMap<String, Object>();    KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");    keyPairGen.initialize(1024);    KeyPair keyPair = keyPairGen.generateKeyPair();    RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();    RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();    map.put("public", publicKey);    map.put("private", privateKey);    return map;}/** * 使用模和指数生成RSA公钥 * 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 * /None/NoPadding】 *  * @param modulus *            模 * @param exponent *            指数 * @return */public static RSAPublicKey getPublicKey(String modulus, String exponent) {    try {        BigInteger b1 = new BigInteger(modulus);        BigInteger b2 = new BigInteger(exponent);        KeyFactory keyFactory = KeyFactory.getInstance("RSA");        RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);        return (RSAPublicKey) keyFactory.generatePublic(keySpec);    } catch (Exception e) {        e.printStackTrace();        return null;    }}/** * 使用模和指数生成RSA私钥 * 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 * /None/NoPadding】 *  * @param modulus *            模 * @param exponent *            指数 * @return */public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {    try {        BigInteger b1 = new BigInteger(modulus);        BigInteger b2 = new BigInteger(exponent);        KeyFactory keyFactory = KeyFactory.getInstance("RSA");        RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2);        return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);    } catch (Exception e) {        e.printStackTrace();        return null;    }}/** * 公钥加密 *  * @param data * @param publicKey * @return * @throws Exception */public static String encryptByPublicKey(String data, RSAPublicKey publicKey)        throws Exception {    Cipher cipher = Cipher.getInstance("RSA");    cipher.init(Cipher.ENCRYPT_MODE, publicKey);    // 模长    int key_len = publicKey.getModulus().bitLength() / 8;    // 加密数据长度 <= 模长-11    String[] datas = splitString(data, key_len - 11);    String mi = "";    //如果明文长度大于模长-11则要分组加密    for (String s : datas) {        mi += bcd2Str(cipher.doFinal(s.getBytes()));    }    return mi;}/** * 私钥解密 *  * @param data * @param privateKey * @return * @throws Exception */public static String decryptByPrivateKey(String data, RSAPrivateKey privateKey)        throws Exception {    Cipher cipher = Cipher.getInstance("RSA");    cipher.init(Cipher.DECRYPT_MODE, privateKey);    //模长    int key_len = privateKey.getModulus().bitLength() / 8;    byte[] bytes = data.getBytes();    byte[] bcd = ASCII_To_BCD(bytes, bytes.length);    System.err.println(bcd.length);    //如果密文长度大于模长则要分组解密    String ming = "";    byte[][] arrays = splitArray(bcd, key_len);    for(byte[] arr : arrays){        ming += new String(cipher.doFinal(arr));    }    return ming;}/** * ASCII码转BCD码 *  */public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {    byte[] bcd = new byte[asc_len / 2];    int j = 0;    for (int i = 0; i < (asc_len + 1) / 2; i++) {        bcd[i] = asc_to_bcd(ascii[j++]);        bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));    }    return bcd;}public static byte asc_to_bcd(byte asc) {    byte bcd;    if ((asc >= '0') &amp;&amp; (asc <= '9'))        bcd = (byte) (asc - '0');    else if ((asc >= 'A') &amp;&amp; (asc <= 'F'))        bcd = (byte) (asc - 'A' + 10);    else if ((asc >= 'a') &amp;&amp; (asc <= 'f'))        bcd = (byte) (asc - 'a' + 10);    else        bcd = (byte) (asc - 48);    return bcd;}/** * BCD转字符串 */public static String bcd2Str(byte[] bytes) {    char temp[] = new char[bytes.length * 2], val;    for (int i = 0; i < bytes.length; i++) {        val = (char) (((bytes[i] &amp; 0xf0) >> 4) &amp; 0x0f);        temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');        val = (char) (bytes[i] &amp; 0x0f);        temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');    }    return new String(temp);}/** * 拆分字符串 */public static String[] splitString(String string, int len) {    int x = string.length() / len;    int y = string.length() % len;    int z = 0;    if (y != 0) {        z = 1;    }    String[] strings = new String[x + z];    String str = "";    for (int i=0; i<x+z; i++) {        if (i==x+z-1 &amp;&amp; y!=0) {            str = string.substring(i*len, i*len+y);        }else{            str = string.substring(i*len, i*len+len);        }        strings[i] = str;    }    return strings;}/** *拆分数组  */public static byte[][] splitArray(byte[] data,int len){    int x = data.length / len;    int y = data.length % len;    int z = 0;    if(y!=0){        z = 1;    }    byte[][] arrays = new byte[x+z][];    byte[] arr;    for(int i=0; i<x+z; i++){        arr = new byte[len];        if(i==x+z-1 &amp;&amp; y!=0){            System.arraycopy(data, i*len, arr, 0, y);        }else{            System.arraycopy(data, i*len, arr, 0, len);        }        arrays[i] = arr;    }    return arrays;}

}

用法：```javapublic static void main(String[] args) throws Exception {        // TODO Auto-generated method stub        HashMap<String, Object> map = RSAUtils.getKeys();        //生成公钥和私钥        RSAPublicKey publicKey = (RSAPublicKey) map.get("public");        RSAPrivateKey privateKey = (RSAPrivateKey) map.get("private");        //模        String modulus = publicKey.getModulus().toString();        //公钥指数        String public_exponent = publicKey.getPublicExponent().toString();        //私钥指数        String private_exponent = privateKey.getPrivateExponent().toString();        //明文        String ming = "123456789";        //使用模和指数生成公钥和私钥        RSAPublicKey pubKey = RSAUtils.getPublicKey(modulus, public_exponent);        RSAPrivateKey priKey = RSAUtils.getPrivateKey(modulus, private_exponent);        //加密后的密文        String mi = RSAUtils.encryptByPublicKey(ming, pubKey);        System.err.println(mi);        //解密后的明文        ming = RSAUtils.decryptByPrivateKey(mi, priKey);        System.err.println(ming);    }