RSA是一种非对称加密算法。现在，很多登陆表单的密码的都采用RSA加密，例如京东中的登陆使用公钥对密码进行加密。
package com.qian.encoded;
import org.apache.commons.codec.binary.Base64;
public class Base64Coded {
public static void main(String[] args) {
String string = "qianyang123";
//编码
String encode = encode(string.getBytes());
System.out.println(string + "\t编码后的字符串为：" + encode);
//解码
String decode = decode(encode.getBytes());
System.out.println(encode + "\t字符串解码后为：" + decode);
}
//base64 解码
public static String decode(byte[] bytes) {
return new String(Base64.decodeBase64(bytes));
}
//base64 编码
public static String encode(byte[] bytes) {
return new String(Base64.encodeBase64(bytes));
}
}
程序的输出结果为：
qianyang123 编码后的字符串为：cWlhbnlhbmcxMjM=
cWlhbnlhbmcxMjM= 字符串解码后为：qianyang123
RSA加密与解密
使用RSA一般需要产生公钥和私钥，当采用公钥加密时，使用私钥解密；采用私钥加密时，使用公钥解密。以下为Java程序：
package com.qian.encoded;
import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
public class RSAEncrypt {
private static Map<Integer, String> keyMap = new HashMap<Integer, String>(); //用于封装随机产生的公钥与私钥
public static void main(String[] args) throws Exception {
//生成公钥和私钥
genKeyPair();
//加密字符串
String message = "df723820";
System.out.println("随机生成的公钥为:" + keyMap.get(0));
System.out.println("随机生成的私钥为:" + keyMap.get(1));
String messageEn = encrypt(message,keyMap.get(0));
System.out.println(message + "\t加密后的字符串为:" + messageEn);
String messageDe = decrypt(messageEn,keyMap.get(1));
System.out.println("还原后的字符串为:" + messageDe);
}
/**
* 随机生成密钥对
* @throws NoSuchAlgorithmException
*/
public static void genKeyPair() throws NoSuchAlgorithmException {
// KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
// 初始化密钥对生成器，密钥大小为96-1024位
keyPairGen.initialize(1024,new SecureRandom());
// 生成一个密钥对，保存在keyPair中
KeyPair keyPair = keyPairGen.generateKeyPair();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 得到私钥
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); // 得到公钥
String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
// 得到私钥字符串
String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
// 将公钥和私钥保存到Map
keyMap.put(0,publicKeyString); //0表示公钥
keyMap.put(1,privateKeyString); //1表示私钥
}
/**
* RSA公钥加密
*
* @param str
* 加密字符串
* @param publicKey
* 公钥
* @return 密文
* @throws Exception
* 加密过程中的异常信息
*/
public static String encrypt( String str, String publicKey ) throws Exception{
//base64编码的公钥
byte[] decoded = Base64.decodeBase64(publicKey);
RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
//RSA加密
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
return outStr;
}
/**
* RSA私钥解密
*
* @param str
* 加密字符串
* @param privateKey
* 私钥
* @return 铭文
* @throws Exception
* 解密过程中的异常信息
*/
public static String decrypt(String str, String privateKey) throws Exception{
//64位解码加密后的字符串
byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
//base64编码的私钥
byte[] decoded = Base64.decodeBase64(privateKey);
RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
//RSA解密
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, priKey);
String outStr = new String(cipher.doFinal(inputByte));
return outStr;
}
}
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原文链接：https://blog.csdn.net/qy20115549/article/details/83105736
