每日一得--非对称加密算法之（RSA）_kfactory.generateprivate(-优快云博客

本文链接：https://blog.youkuaiyun.com/xoopx/article/details/44225223

本文提供了一个Java实现的RSA加密解密及数字签名的完整示例，包括生成密钥对、使用私钥加密与公钥解密、公钥加密与私钥解密的过程，并展示了如何生成及验证数字签名。

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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 RSAMain {
private static String str= "husq RSA test";
/**
* @param args
*/
public static void main(String[] args) {
jdkRSA();
}

public static void jdkRSA(){
try{
//1 初始化秘钥
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 : "+ Base64.encodeBase64String(rsaPublicKey.getEncoded()));
System.out.println("private key : "+ Base64.encodeBase64String(rsaPrivateKey.getEncoded()));

//2 私钥加密，公钥解密---加密
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
KeyFactory kFactory = KeyFactory.getInstance("RSA");
PrivateKey privateKey = kFactory.generatePrivate(pkcs8EncodedKeySpec);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
byte[] result = cipher.doFinal(str.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());
kFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = kFactory.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());
kFactory = KeyFactory.getInstance("RSA");
publicKey = kFactory.generatePublic(x509EncodedKeySpec);
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
result = cipher.doFinal(str.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());
kFactory = KeyFactory.getInstance("RSA");
privateKey = kFactory.generatePrivate(pkcs8EncodedKeySpec);
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);

cipher.doFinal(result);

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

//6,用私钥对信息生成数字签名

Signature signature = Signature.getInstance(“RSA”);
signature.initSign(privateKey);
signature.update(result);
System.out.println("用私钥对信息生成数字签名："+encryptBASE64(signature.sign()));

//7,验证签名是否正常

Signature signature = Signature.getInstance(“RSA”);
signature.initVerify(pubKey);
signature.update(result);
// 验证签名是否正常

System.out.println("验证签名是否正常："+ signature.verify(decryptBASE64(sign)));

}catch(Exception e){
e.printStackTrace();
}
}

}