java 中rsa的方式实现非对称加密的实例

rsa通俗理解：

你只要去想：既然是加密，那肯定是不希望别人知道我的消息，所以只有我才能解密，所以可得出公钥负责加密，私钥负责解密；同理，既然是签名，那肯定是不希望有人冒充我发消息，只有我才能发布这个签名，所以可得出私钥负责签名，公钥负责验证。

实现代码：

package com.sahadev;

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 rsa {

public static void main(string[] args) {

jdkrsa();

}

public static void jdkrsa() {

try {

// 构建密钥对儿

keypairgenerator keypairgenerator = keypairgenerator.getinstance("rsa");

keypairgenerator.initialize(512);

keypair keypair = keypairgenerator.generatekeypair();

rsapublickey rsapublickey = (rsapublickey) keypair.getpublic();

rsaprivatekey rsaprivatekey = (rsaprivatekey) keypair.getprivate();

system.out.println("public key : " + org.apache.commons.codec.binary.base64.encodebase64string(rsapublickey.getencoded()));

system.out.println("private key : " + org.apache.commons.codec.binary.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 privatekey = keyfactory.generateprivate(pkcs8encodedkeyspec);

cipher cipher = cipher.getinstance("rsa");

cipher.init(cipher.encrypt_mode, privatekey);

byte[] result = cipher.dofinal(dh.src.getbytes());

system.out.println("私钥加密，公钥解密------加密 : " + base64.encodebase64string(result));

// 3.私钥加密，公钥解密---解密

x509encodedkeyspec x509encodedkeyspec = new x509encodedkeyspec(rsapublickey.getencoded());

keyfactory = keyfactory.getinstance("rsa");

publickey publickey = keyfactory.generatepublic(x509encodedkeyspec);

cipher = cipher.getinstance("rsa");

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));

// 4.公钥加密，私钥解密---加密

x509encodedkeyspec = new x509encodedkeyspec(rsapublickey.getencoded());

keyfactory = keyfactory.getinstance("rsa");

publickey = keyfactory.generatepublic(x509encodedkeyspec);

cipher = cipher.getinstance("rsa");

cipher.init(cipher.encrypt_mode, publickey);

result = cipher.dofinal(dh.src.getbytes());

system.out.println("公钥加密，私钥解密------加密 : " + base64.encodebase64string(result));

// 5.公钥加密，私钥解密---解密

pkcs8encodedkeyspec = new pkcs8encodedkeyspec(rsaprivatekey.getencoded());

keyfactory = keyfactory.getinstance("rsa");

privatekey = keyfactory.generateprivate(pkcs8encodedkeyspec);

cipher = cipher.getinstance("rsa");

cipher.init(cipher.decrypt_mode, privatekey);

result = cipher.dofinal(result);

system.out.println("公钥加密，私钥解密------解密 : " + new string(result));

} catch (exception e) {

e.printstacktrace();

}

}

}

附上输出结果：

public key : mfwwdqyjkozihvcnaqebbqadswawsajbajcfshop5xm94r2atbe++amzmzjtxhxdpqmmq9al1cethr2xtac+eckv32kzb4r8c/6vobnbfd8swx9fu5n2y6ccaweaaq==

private key : miibvaibadanbgkqhkig9w0baqefaascat4wgge6ageaakealwwygg/ngb3ivzpnt775oxkzmm1cfeomqyxd1ovvws2gvze1pz4rys/fyrnvhhwl/q85s0f93yxbh0vtk3blpwidaqabakbdaa7rabug6irgykztyfcmjxaud5asl358jnoafuctmo4skfxh1vr4enfue0lt0zj3ckvh0o9uqdng0r4jeograiea3kuxps9og0axuxlggg0e7b1os5c3gnrh2fmqapjtpy0ciqcvm4epfdrjjnqim0atvbt5jznw3pru33pdyiswuomhawigdolmsuzjxj2y5si2cyigoymw/g9f99tovlbvzhy8y+ucif94mvu/uqdgnljsmv3tu4cpklmxrzq9lhduu1hpujcbaieay/0os2q9ebfmpwhsgxf4wmxj4wg0xznfwxsezb0qxzk=

私钥加密，公钥解密------加密 : nxf87irbemk3x/fw7iwy4gua8ap4rvj4djsp2cjjsoo5x/schhkdvytlm+9touavmeukwk5wh70g53q7+e73zg==

私钥加密，公钥解密------解密 : hello,sahadev!

公钥加密，私钥解密------加密 : hjl8928jcbntvcrhkayaxqnjmiiaktbskhff2i01pbahtfgh6gjtcp1i345/3i9ozwovfxvi/oxgvjsisg7moq==

公钥加密，私钥解密------解密 : hello,sahadev!

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