Java 加解密工具类

一、对称加密算法 

加密和解密使用相同密钥的加密算法。常用的算法包括DES、3DES、AES、DESX、Blowfish、RC4、RC5、RC6。

DES（Data Encryption Standard）：数据加密标准，速度较快，适用于加密大量数据的场合。

3DES（Triple DES）：是基于DES，对一块数据用三个不同的密钥进行三次加密，强度更高。

AES（Advanced Encryption Standard）：高级加密标准，速度快，安全级别高【128位秘钥】；

二、非对称加密算法

加密和解密使用不同密钥的加密算法，也称为公私钥加密。常见的算法包括RSA、DSA（数字签名用）、ECC（移动设备用）、Diffie-Hellman、El Gamal。

RSA：由 RSA 公司发明，是一个支持变长密钥的公共密钥算法，需要加密的文件块的长度也是可变的；【建议1024位秘钥】
DSA：数字签名算法，是一种标准的 DSS（数字签名标准）
ECC：椭圆曲线密码编码学【建议160位秘钥】。

ECC VS RSA
1）抗攻击性强。相同的密钥长度，其抗攻击性要强很多倍。
2）计算量小，处理速度快。ECC总的速度比RSA、DSA要快得多。
3）存储空间占用小。ECC的密钥尺寸和系统参数与RSA、DSA相比要小得多，意味着它所占的存贮空间要小得多。这对于加密算法在IC卡上的应用具有特别重要的意义。
4）带宽要求低。当对长消息进行加解密时，三类密码系统有相同的带宽要求，但应用于短消息时ECC带宽要求却低得多。带宽要求低使ECC在无线网络领域具有广泛的应用前景。

三、散列算法

除法散列法 平方散列法 斐波那契（Fibonacci）散列法 随机数法

单向散列函数一般用于产生消息摘要，密钥加密等，常用的算法包括MD2、MD4、MD5、HAVAL、SHA、SHA-1、HMAC、HMAC-MD5、HMAC-SHA1。

MD5（Message Digest Algorithm 5）：是RSA数据安全公司开发的一种单向散列算法，非可逆，相同的明文产生相同的密文。

SHA（Secure Hash Algorithm）：可以对任意长度的数据运算生成一个160位的数值；

SHA-1 VS MD5 [二者均由MD4导出]
1）SHA-1摘要比MD5摘要长32位。使用强行技术，产生任何一个报文使其摘要等于给定报摘要的难度对MD5是2^(128)数量级的操作，而对SHA-1则是2^(160)数量级的操作。这样，SHA-1对强行攻击有更大的强度。
2）MD5易受密码分析的攻击，SHA-1显得不易受这样的攻击。
3）在相同的硬件上，SHA-1的运行速度比MD5慢。

四、加密算法的选择

1.单方密码存储建议直接使用散列算法（MD5即可，配合密码更新策略）。

2.内部信息加密传输建议使用对称加密效率跟高（AES）。

3.外部数据传输建议使用非对称加密，秘钥保存更安全（RSA）。

4.HTTPS高级用法：采用非对称加密算法管理对称算法的密钥，然后用对称加密算法加密数据，这样我们就集成了两类加密算法的优点，既实现了加密速度快的优点，又实现了安全方便管理密钥的优点。

五、上源码

5.1 AES对称加密

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang3.ArrayUtils;
import org.springframework.util.StringUtils;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;

/**
 * <p>
 * AES加密工具
 * </p>
 *
 * @author ocean
 * @version 1.0.0
 * @date 2023/5/4 14:51
 */
@Slf4j
public class AESUtils {

    // 秘钥 16
    private static final String SECRET_KEY = "1111111111111111";
    // 秘钥 24
    //private static final String SECRET_KEY = "111111111111111122222222";
    // 秘钥 32
    //private static final String SECRET_KEY = "11111111111111112222222233333333";

    // 算法
    private static final String ALGORITHM = "AES";

    private static final String UTF8 = StandardCharsets.UTF_8.name();

    /**
     * 字符串加密
     *
     * @param message   明文字符串
     * @param secretKey 秘钥
     * @return 加密字符串
     */
    public static String encryption(String message, String secretKey) {
        if (!StringUtils.hasLength(message)) {
            log.error("encryption message should not be null or empty.");
        }
        byte[] encodeBytes = encryption(message.getBytes(StandardCharsets.UTF_8), secretKey);
        return Base64.encodeBase64String(encodeBytes);
    }

    /**
     * 字符串加密
     *
     * @param messageBytes 明文字节数组
     * @param secretKey    秘钥
     * @return 加密字节数组
     */
    public static byte[] encryption(byte[] messageBytes, String secretKey) {
        if (ArrayUtils.isEmpty(messageBytes)) {
            log.error("encryption message should not be empty.");
        }
        if (!StringUtils.hasLength(secretKey)) {
            log.error("secretKey {}, encryption key should not be null or empty.", secretKey);
        }
        Cipher cipher = getCipher(secretKey, Cipher.ENCRYPT_MODE);
        byte[] encryptionBytes = null;
        try {
            encryptionBytes = cipher.doFinal(messageBytes);
        } catch (Exception e) {
            log.error("encryption fail. ", e);
        }
        return encryptionBytes;
    }

    /**
     * 字符串加密
     *
     * @param encryptionMessage 加密字符串
     * @param secretKey         秘钥
     * @return 明文字符串
     */
    public static String decrypt(String encryptionMessage, String secretKey) {
        if (!StringUtils.hasLength(encryptionMessage)) {
            log.error("decrypt encryptionMessage should not be null or empty.");
        }
        byte[] decodeBytes = decrypt(Base64.decodeBase64(encryptionMessage.getBytes(StandardCharsets.UTF_8)), secretKey);
        return new String(decodeBytes, StandardCharsets.UTF_8);
    }


    /**
     * 字符串加密
     *
     * @param encryptedBytes 加密字节数组
     * @param secretKey      秘钥
     * @return 明文字节数组
     */
    public static byte[] decrypt(byte[] encryptedBytes, String secretKey) {
        if (ArrayUtils.isEmpty(encryptedBytes)) {
            log.error("decrypt encryptedBytes should not be empty.");
        }
        if (!StringUtils.hasLength(secretKey)) {
            log.error("secretKey {}, decrypt key should not be null or empty.", secretKey);
        }
        Cipher cipher = getCipher(secretKey, Cipher.DECRYPT_MODE);
        byte[] decodeBytes = null;
        try {
            decodeBytes = cipher.doFinal(encryptedBytes);
        } catch (Exception e) {
            log.error("decrypt fail. ", e);
        }
        return decodeBytes;
    }

    private static Cipher getCipher(String key, int mode) {
        Cipher cipher = null;
        SecretKey secretKey;
        try {
            cipher = Cipher.getInstance(ALGORITHM);
            byte[] keyBytes = key.getBytes(UTF8);
            secretKey = new SecretKeySpec(keyBytes, ALGORITHM);
            cipher.init(mode, secretKey);
        } catch (Exception e) {
            log.error("getAESCipher fail. ", e);
        }
        return cipher;
    }

    public static void main(String[] args) {
        String data = "ocean测试!@#";
        log.info("AES秘钥长度只能为16、24、32:{}", SECRET_KEY.getBytes(StandardCharsets.UTF_8).length);
        String encryptionData = encryption(data, SECRET_KEY);
        log.info("加密后:{}", encryptionData);
        String decryptData = decrypt(encryptionData, SECRET_KEY);
        log.info("解密后:{}", decryptData);
    }


}

5.2 RSA非对称加密

PSCK#8 - PSCK#1
<!-- https://mvnrepository.com/artifact/org.bouncycastle/bcprov-jdk15on -->
<dependency>
<groupId>org.bouncycastle</groupId>
<artifactId>bcprov-jdk15on</artifactId>
<version>1.52</version>
</dependency>

import java.io.StringWriter;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.util.io.pem.PemObject;
import org.bouncycastle.util.io.pem.PemWriter;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class RsaUtils {

	public static final int KEY_SIZE = 2048;
	public static final String ALGORITHM = "RSA";


	public static final String PUBLIC_KEY = "xxxxpublicKeyxxxx";
	public static final String PRIVATE_KEY = "xxxxprivateKeyxxxx";

	public static final String CLEAR_TEXT_STRING = "明文字符串";

	public static BASE64Encoder encoder = new BASE64Encoder();
	public static BASE64Decoder decoder = new BASE64Decoder();

	public static void main(String[] args) throws Exception {
		// PSCK#8
		Map<String, String> keyMap = RsaUtil.generateKeyBytes();
		System.out.println("PSCK#8-PRIVATEKEY:"+ keyMap.get(RsaUtil.PRIVATE_KEY));
		System.out.println("PSCK#8-PUBLICKEY:" + keyMap.get(RsaUtil.PUBLIC_KEY));
		
		PublicKey publicKey8 = RsaUtil.restorePublicKey(keyMap.get(RsaUtil.PUBLIC_KEY));
		PrivateKey privateKey8 = RsaUtil.restorePrivateKey(keyMap.get(RsaUtil.PRIVATE_KEY));

		
		// ============公钥加密-私钥解密============
		Cipher cipher = Cipher.getInstance(ALGORITHM);
		cipher.init(Cipher.ENCRYPT_MODE, publicKey8);
		String messageEn = Base64.encodeBase64String(cipher.doFinal(CLEAR_TEXT_STRING.getBytes("UTF-8")));
		System.out.println(CLEAR_TEXT_STRING + "t加密后的字符串为:" + messageEn);
		cipher.init(Cipher.DECRYPT_MODE, privateKey8);
		String messageDe = new String(cipher.doFinal(Base64.decodeBase64(messageEn.getBytes("UTF-8"))));
		System.out.println("还原后的字符串为:" + messageDe);
		// ============公钥加密-私钥解密============

	

		// ============PSCK#8>PSCK#1============
		byte[] privBytes = privateKey8.getEncoded();
		PrivateKeyInfo pkInfo = PrivateKeyInfo.getInstance(privBytes);
		ASN1Encodable encodable = pkInfo.getPrivateKey();
		ASN1Primitive primitive = encodable.toASN1Primitive();

		byte[] privateKeyPKCS1 = primitive.getEncoded();
		PemObject pemObject = new PemObject("RSA PRIVATE KEY", privateKeyPKCS1);
		StringWriter stringWriter = new StringWriter();
		PemWriter pemWriter = new PemWriter(stringWriter);
		pemWriter.writeObject(pemObject);
		pemWriter.close();
		String pemString = stringWriter.toString();
		System.out.println("PSCK#1-PRIVATEKEY:" + pemString);

		byte[] pubBytes = publicKey8.getEncoded();
		SubjectPublicKeyInfo spkInfo = SubjectPublicKeyInfo
				.getInstance(pubBytes);
		ASN1Primitive punlic = spkInfo.parsePublicKey();
		byte[] publicKeyPKCS1 = punlic.getEncoded();

		PemObject punlicpemObject = new PemObject("RSA PUBLIC KEY",
				publicKeyPKCS1);
		StringWriter punlicstringWriter = new StringWriter();
		PemWriter punlicpemWriter = new PemWriter(punlicstringWriter);
		punlicpemWriter.writeObject(punlicpemObject);
		punlicpemWriter.close();
		String publicemString = punlicstringWriter.toString();
		System.out.println("PSCK#8-PUBLICKEY:" + publicemString);
		// ============PSCK#8>PSCK#1============

		// ============私钥签名公钥验签============
		// PSCK#8-PRIVATEKEY 私钥签名
		Signature signature = Signature.getInstance("SHA256WithRSA");
		signature.initSign(privateKey8);
		signature.update(CLEAR_TEXT_STRING.getBytes());
		byte[] signed = signature.sign();
		String sign = encoder.encode(signed);

		// PSCK#8-PUBLICKEY 公钥验签
		signature.initVerify(publicKey8);
		signature.update(CLEAR_TEXT_STRING.getBytes());
		boolean verify = signature.verify(decoder.decodeBuffer(sign));

		System.out.println("CLEAR_TEXT_STRING:" + CLEAR_TEXT_STRING);
		System.out.println("SIGN:" + sign.replaceAll("r|n", ""));
		System.out.println(verify);
		// ============私钥签名公钥验签============
	}

	/**
	 * 公私钥生成
	 * 
	 * @return
	 */
	public static Map<String, String> generateKeyBytes() {
		try {
			KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(ALGORITHM);
			keyPairGenerator.initialize(KEY_SIZE);
			KeyPair keyPair = keyPairGenerator.generateKeyPair();

			RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
			RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

			Map<String, String> keyMap = new HashMap<String, String>();
			keyMap.put(PUBLIC_KEY, new String(Base64.encodeBase64(publicKey.getEncoded())));
			keyMap.put(PRIVATE_KEY, new String(Base64.encodeBase64(privateKey.getEncoded())));
			return keyMap;
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		return null;
	}
	/**
	 * 公钥生成
	 * @param key
	 * @return
	 */
	public static PublicKey restorePublicKey(String key) {
		X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(Base64.decodeBase64(key));
		try {
			KeyFactory factory = KeyFactory.getInstance(ALGORITHM);
			PublicKey publicKey = factory.generatePublic(x509EncodedKeySpec);
			return publicKey;
		} catch (NoSuchAlgorithmException | InvalidKeySpecException e) {
			e.printStackTrace();
		}
		return null;
	}
	
	/**
	 * 私钥生成
	 * @param key
	 * @return
	 */
    public static PrivateKey restorePrivateKey(String key) {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(key));
        try {
            KeyFactory factory = KeyFactory.getInstance(ALGORITHM);
            PrivateKey privateKey = factory
                    .generatePrivate(pkcs8EncodedKeySpec);
            return privateKey;
        } catch (NoSuchAlgorithmException | InvalidKeySpecException e) {
            e.printStackTrace();
        }
        return null;
    }

}

5.3 MD5散列算法

import lombok.extern.slf4j.Slf4j;

import java.security.MessageDigest;


@Slf4j
public class MD5Util {
    public static final int SIZE_FACTOR = 2;
    private static final String[] hexDigits = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};

    public static String MD5Encode(String origin, String charsetname) {
        String resultString = null;
        try {
            resultString = origin;
            MessageDigest md = MessageDigest.getInstance("MD5");
            if (charsetname == null || "".equals(charsetname)) {
                resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
            } else {
                resultString = byteArrayToHexString(md.digest(resultString.getBytes(charsetname)));
            }
        } catch (Exception exception) {
            log.error("MD5Util MD5Encode error", exception);
        }
        return resultString;
    }

    private static String byteArrayToHexString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));
        }
        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n += 256;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static String encode(String str) {
        try {
            byte[] hash = MessageDigest.getInstance("MD5").digest(str.getBytes("utf-8"));
            StringBuilder hex = new StringBuilder(hash.length * SIZE_FACTOR);
            for (byte b : hash) {
                hex.append(String.format("%02x", b));
            }
            return hex.toString();
        } catch (Exception e) {
            log.error("MD5 encode error for {}, error is {}", str, e.getMessage(), e);
        }
        return null;
    }
}

代码007普通

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