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;
}
}
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