cn.micro.core.util.RsaUtil Maven / Gradle / Ivy

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package cn.micro.core.util;

import javax.crypto.Cipher;
import java.io.IOException;
import java.security.*;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

public class RsaUtil {

    private RsaUtil() {

    }

    /**
     * 算法名称
     */
    private static final String ALGORITHM = "RSA";

    /**
     * 密钥长度
     */
    private static final int KEY_SIZE = 512;

    public static KeyPair getKeyPair() throws Exception {
        return getKeyPair(KEY_SIZE);
    }

    /**
     * 获取秘钥对
     *
     * @param keySize 密钥长度
     * @return 密钥对
     * @throws Exception 异常
     */
    public static KeyPair getKeyPair(int keySize) throws Exception {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(KEY_SIZE);
        return keyPairGenerator.generateKeyPair();
    }

    /**
     * 获取公钥(Base64编码)
     */
    public static String getPublicKey(KeyPair keyPair) {
        PublicKey publicKey = keyPair.getPublic();
        byte[] bytes = publicKey.getEncoded();
        return bytesToBase64(bytes);
    }

    /**
     * 获取私钥(Base64编码)
     */
    public static String getPrivateKey(KeyPair keyPair) {
        PrivateKey privateKey = keyPair.getPrivate();
        byte[] bytes = privateKey.getEncoded();
        return bytesToBase64(bytes);
    }

    /**
     * 公钥加密
     */
    public static byte[] publicEncrypt(byte[] content, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(content);
    }

    /**
     * 私钥解密
     */
    public static byte[] privateDecrypt(byte[] content, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(content);
    }

    /**
     * 签名
     *
     * @param data       待签名数据
     * @param privateKey 私钥
     * @return 签名
     */
    public static String sign(byte[] data, PrivateKey privateKey) throws Exception {
        byte[] keyBytes = privateKey.getEncoded();
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey key = keyFactory.generatePrivate(keySpec);
        Signature signature = Signature.getInstance("MD5withRSA");
        signature.initSign(key);
        signature.update(data);
        return bytesToBase64(signature.sign());
    }

    /**
     * 验签
     *
     * @param data      原始字符串
     * @param publicKey 公钥
     * @param sign      签名
     * @return 是否验签通过
     */
    public static boolean verify(byte[] data, PublicKey publicKey, String sign) throws Exception {
        byte[] keyBytes = publicKey.getEncoded();
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey key = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance("MD5withRSA");
        signature.initVerify(key);
        signature.update(data);
        return signature.verify(base64ToBytes(sign));
    }

    /**
     * 字节数组转Base64编码
     */
    public static String bytesToBase64(byte[] bytes) {
        Base64.Encoder encoder = Base64.getEncoder();
        return encoder.encodeToString(bytes);
    }

    /**
     * Base64编码转字节数组
     */
    public static byte[] base64ToBytes(String base64Key) throws IOException {
        Base64.Decoder decoder = Base64.getDecoder();
        return decoder.decode(base64Key);
    }

    /**
     * 根据公钥的 Base64 文本创建公钥对象
     */
    public static RSAPublicKey getPublicKey(String pubKeyBase64) throws Exception {
        // 把 公钥的Base64文本 转换为已编码的 公钥bytes
        byte[] encPubKey = base64ToBytes(pubKeyBase64);

        // 创建 已编码的公钥规格
        X509EncodedKeySpec encPubKeySpec = new X509EncodedKeySpec(encPubKey);

        // 获取指定算法的密钥工厂, 根据 已编码的公钥规格, 生成公钥对象
        return (RSAPublicKey) KeyFactory.getInstance(ALGORITHM).generatePublic(encPubKeySpec);
    }

    /**
     * 根据私钥的 Base64 文本创建私钥对象
     */
    public static PrivateKey getPrivateKey(String priKeyBase64) throws Exception {
        // 把 私钥的Base64文本 转换为已编码的 私钥bytes
        byte[] encPriKey = base64ToBytes(priKeyBase64);

        // 创建 已编码的私钥规格
        PKCS8EncodedKeySpec encPriKeySpec = new PKCS8EncodedKeySpec(encPriKey);

        // 获取指定算法的密钥工厂, 根据 已编码的私钥规格, 生成私钥对象
        return KeyFactory.getInstance(ALGORITHM).generatePrivate(encPriKeySpec);
    }

}