RSA非对称加密算法详解-优快云博客

本文通过Java代码实现介绍了RSA非对称加密算法的工作原理及应用，包括密钥生成、私钥加密与公钥解密的过程，并展示了如何使用Apache Commons Codec库进行Base64编码。

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RSA是一种被广泛接受并实现，提供私钥加密和公钥解密或者私钥加密公钥解密的算法。相对比较慢，底层是大数字因子分解。

package password.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;

import org.apache.commons.codec.binary.Base64;

public class RSA2 {
public static String RSA = "RSA";
private static final String src = "password";

public static void main(String[] args) {
try {
jdkRSA();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

// rsa实现非对称加密
public static void jdkRSA() throws Exception {
// 1.初始化密钥
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(RSA);
keyPairGenerator.initialize(512);
KeyPair generateKeyPair = keyPairGenerator.generateKeyPair();

// 初始化公钥
RSAPublicKey rsaPublicKey = (RSAPublicKey) generateKeyPair.getPublic();
// 初始化私钥
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) generateKeyPair.getPrivate();
System.out.println("public key公钥：" + Base64.encodeBase64String(rsaPublicKey.getEncoded()));
System.out.println("private key私钥：" + Base64.encodeBase64String(rsaPrivateKey.getEncoded()));
// 2.私钥加密——公钥解密,加密：
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
KeyFactory keyFactory = KeyFactory.getInstance(RSA);
PrivateKey generatePrivate = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
Cipher instance = Cipher.getInstance(RSA);
instance.init(Cipher.ENCRYPT_MODE, rsaPrivateKey);
byte[] doFinal = instance.doFinal(src.getBytes());
System.out.println("用公钥加密，私钥解密——加密：" + Base64.encodeBase64String(doFinal));
// 3.私钥加密——公钥解密：解密：
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
keyFactory = KeyFactory.getInstance(RSA);
PublicKey generatePublic = keyFactory.generatePublic(x509EncodedKeySpec);
Cipher instance2 = Cipher.getInstance(RSA);
instance2.init(Cipher.DECRYPT_MODE, generatePublic);
doFinal = instance2.doFinal(doFinal);
System.out.println("公钥解密结果：" + new String(doFinal));
// 4.公钥加密——私钥解密,加密：
x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
keyFactory = KeyFactory.getInstance(RSA);
generatePublic = keyFactory.generatePublic(x509EncodedKeySpec);
instance2 = Cipher.getInstance(RSA);
instance2.init(Cipher.ENCRYPT_MODE, generatePublic);
doFinal = instance2.doFinal(src.getBytes());
System.out.println("公钥加密结果：" + Base64.encodeBase64String(doFinal));
// 5.公钥加密——私钥解密,解密：
new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
keyFactory = KeyFactory.getInstance(RSA);
generatePrivate = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
instance = Cipher.getInstance(RSA);
instance.init(Cipher.DECRYPT_MODE, rsaPrivateKey);
doFinal = instance.doFinal(doFinal);

System.out.println("用私钥加密，公钥解密——解密：" + new String(doFinal));

}

}