JAVA 实现 RSA 加密解密

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2023-12-01

RSA 工具类。提供加密，解密，生成密钥对等方法。

RSA加密原理概述：
RSA的安全性依赖于大数的分解，公钥和私钥都是两个大素数（大于100的十进制位）的函数。
据猜测，从一个密钥和密文推断出明文的难度等同于分解两个大素数的积
密钥的产生：
1.选择两个大素数 p,q ,计算 n=p*q;
2.随机选择加密密钥 e ,要求 e 和 (p-1)*(q-1)互质
3.利用 Euclid 算法计算解密密钥 d , 使其满足 e*d = 1(mod(p-1)*(q-1)) (其中 n,d 也要互质)
4:至此得出公钥为 (n,e) 私钥为 (n,d)
RSA速度
由于进行的都是大数计算，使得RSA最快的情况也比DES慢上100倍，无论是软件还是硬件实现。
速度一直是RSA的缺陷。一般来说只用于少量数据加密。

[java] view plain copy

package com.security.rsa;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
public class RSAsecurity {
public static String src="RSA 加密字符串";
public void priENpubDE() {
try {
//1.初始化秘钥
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
//秘钥长度
keyPairGenerator.initialize(512);
//初始化秘钥对
KeyPair keyPair = keyPairGenerator.generateKeyPair();
//公钥
RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
//私钥
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
//2.私钥加密，公钥解密----加密
//生成私钥
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
KeyFactory keyFactory =KeyFactory.getInstance("RSA");
PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
//Cipher类为加密和解密提供密码功能，通过getinstance实例化对象
Cipher cipher =Cipher.getInstance("RSA");
//初始化加密
cipher.init(Cipher.ENCRYPT_MODE,privateKey);
byte[] result = cipher.doFinal(src.getBytes());
System.out.println("私钥加密，公钥解密----加密:"+Base64.encode(result));
//3.私钥加密，公钥解密----解密
//生成公钥
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
keyFactory=KeyFactory.getInstance("RSA");
PublicKey publicKey= keyFactory.generatePublic(x509EncodedKeySpec);
cipher = Cipher.getInstance("RSA");
//初始化解密
cipher.init(Cipher.DECRYPT_MODE,publicKey);
result = cipher.doFinal(result);
System.out.println("私钥加密，公钥解密----解密:"+new String(result));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void pubENpriDE() {
try {
//1.初始化秘钥
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
//秘钥长度
keyPairGenerator.initialize(512);
//初始化秘钥对
KeyPair keyPair = keyPairGenerator.generateKeyPair();
//公钥
RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
//私钥
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
//2.公钥加密，私钥解密----加密
X509EncodedKeySpec x509EncodedKeySpec=new X509EncodedKeySpec(rsaPublicKey.getEncoded());
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
//初始化加密
//Cipher类为加密和解密提供密码功能，通过getinstance实例化对象
Cipher cipher =Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE,publicKey);
//加密字符串
byte[] result = cipher.doFinal(src.getBytes());
System.out.println("公钥加密，私钥解密----加密:"+Base64.encode(result));
//3.公钥加密，私钥解密-----解密
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
keyFactory=KeyFactory.getInstance("RSA");
PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
//初始化解密
cipher.init(Cipher.DECRYPT_MODE, privateKey);
//解密字符串
result = cipher.doFinal(result);
System.out.println("公钥加密，私钥解密-----解密:"+new String(result));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

测试：

[java] view plain copy

package com.secutiry.rsa;
import com.security.rsa.RSAsecurity;
public class RSAtest {
public static void main(String[] args) {
RSAsecurity rsAsecurity = new RSAsecurity();
System.out.println("私钥加密公钥解密例：");
rsAsecurity.priENpubDE();
System.out.println("公钥加密私钥解密例：");
rsAsecurity.pubENpriDE();
}
}

测试结果：

源代码下载地址

http://download.csdn.net/download/u013400939/8517989点击打开链接