一、MD5加密

密文形式：5eb63bbbe01eeed093cb22bb8f5acdc3

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;public class MD5 {public static String stringToMD5(String plainText) {byte[] secretBytes = null;try {secretBytes = MessageDigest.getInstance("md5").digest(plainText.getBytes());} catch (NoSuchAlgorithmException e) {throw new RuntimeException("没有这个md5算法！");}String md5code = new BigInteger(1, secretBytes).toString(16);for (int i = 0; i < 32 - md5code.length(); i++) {md5code = "0" + md5code;}return md5code;}public static void main(String[] args) {System.out.println(stringToMD5("hello world"));}
}

二、RSA加解密(公加私解，私加公解)

密文形式：W1WTmVo870wB9t6/kGxTV4b2wuI7iHGLNDP+24SyD45==

package com.bytedance.frameworks.core.encrypt;import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;
import javax.crypto.Cipher;
import java.security.KeyFactory;
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;public class RSA {public static String RSAEncryptByPublickey(String str, String publicKey) throws Exception {/* RSA通过公钥加密 *///base64编码的公钥byte[] decoded = Base64.decode(publicKey);RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));//RSA加密Cipher cipher = Cipher.getInstance("RSA");cipher.init(Cipher.ENCRYPT_MODE, pubKey);String outStr = Base64.encode(cipher.doFinal(str.getBytes("UTF-8")));return outStr;}public static String RSAEncryptByPrivatekey(String content,String private_key) {/* RSA通过私钥加密 */String charset = "utf-8";try {PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64.decode(private_key));KeyFactory keyf = KeyFactory.getInstance("RSA");PrivateKey priKey = keyf.generatePrivate(priPKCS8);java.security.Signature signature = java.security.Signature.getInstance("SHA1WithRSA");signature.initSign(priKey);signature.update(content.getBytes(charset));byte[] signed = signature.sign();return Base64.encode(signed);} catch (Exception e) {e.printStackTrace();}return null;}public static String RSADecryptByPublicKey(String str, String publicKey) throws Exception {/* RSA通过公钥解密 */byte[] inputByte = Base64.decode(str);//base64编码的私钥byte[] decoded = Base64.decode(publicKey);PublicKey pubKey =  KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));//RSA解密Cipher cipher = Cipher.getInstance("RSA");cipher.init(Cipher.DECRYPT_MODE, pubKey);String outStr = new String(cipher.doFinal(inputByte));return outStr;}public static String RSADecryptByPrivateKey(String data, String privateKey) throws Exception {/* RSA通过私钥解密 */byte[] inputByte = Base64.decode(data);//base64编码的私钥byte[] decoded = Base64.decode(privateKey);RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));//RSA解密Cipher cipher = Cipher.getInstance("RSA");cipher.init(Cipher.DECRYPT_MODE, priKey);String outStr = new String(cipher.doFinal(inputByte));String str1 = outStr.substring(0,32);String hex = base64Tohex(str1);String Des_key = hex.substring(0,16);return Des_key;}public static String byteToHex(byte b){String hexString = Integer.toHexString(b & 0xFF);//由于十六进制是由0~9、A~F来表示1~16，所以如果Byte转换成Hex后如果是<16,就会是一个字符（比如A=10），通常是使用两个字符来表示16进制位的,//假如一个字符的话，遇到字符串11，这到底是1个字节，还是1和1两个字节，容易混淆，如果是补0，那么1和1补充后就是0101，11就表示纯粹的11if (hexString.length() < 2){hexString = new StringBuilder(String.valueOf(0)).append(hexString).toString();}return hexString.toUpperCase();}public static String bytesToHex(byte[] bytes){StringBuffer sb = new StringBuffer();if (bytes != null && bytes.length > 0){for (int i = 0; i < bytes.length; i++) {String hex = byteToHex(bytes[i]);sb.append(hex);}}return sb.toString();}public static String base64Tohex(String bstxt){byte[] bs = Base64.decode(bstxt);String hex = bytesToHex(bs);return hex.toLowerCase();}public static void main(String[] args) {}
}

三、RSA私钥加密

package com.bytedance.frameworks.core.encrypt;import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;
import sun.misc.BASE64Decoder;import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;public class RSAEncrypt {public static final String KEY_ALGORTHM = "RSA";public static final String SIGNATURE_ALGORITHM = "SHA256WithRSA";public static String RSAEnByPrivate(String content,String PrivateKey) throws Exception {// BC模式java.security.Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());//解密私钥byte[] keyBytes = decryptBASE64(PrivateKey);// byte[] keyBytes = privateKey.getBytes();//构造PKCS8EncodedKeySpec对象PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(keyBytes);//指定加密算法KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORTHM);//取私钥匙对象PrivateKey privateKey2 = keyFactory.generatePrivate(pkcs8EncodedKeySpec);//用私钥对信息生成数字签名Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);signature.initSign(privateKey2);signature.update(content.getBytes());return Base64.encode(signature.sign());}public static byte[] decryptBASE64(String key) throws Exception {return (new BASE64Decoder()).decodeBuffer(key);}public static void main(String[] args) throws Exception  {String content = "xxx";String PrivateKey = "xxx";System.out.println(RSAEnByPrivate(content,PrivateKey));}}

四、RSA私钥加密PKCS1Padding模式

    public static String encryptByPrivateKey(String content,String privateKey) throws Exception {byte[] keyBytes = Base64.decode(privateKey);PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance("RSA");PrivateKey PrivateKey = keyFactory.generatePrivate(keySpec);Cipher cipher = Cipher.getInstance("RSA");cipher.init(Cipher.ENCRYPT_MODE, PrivateKey);byte[] cipherText = cipher.doFinal(content.getBytes());String cipherStr = Base64.encode(cipherText);return cipherStr;}