目錄

• 定義
• 常用對稱加密算法
• • • DES
    • 3DES
    • AES
    • PEB
• 常用對稱加密算法的java實現
• • • DES實現
    • 3DES實現
    • AES實現
    • PEB實現

定義

原文通過加密秘鑰生成密文，密文通過解密秘鑰得到原文。
對于加密秘鑰和解密秘鑰是相同的算法，就叫對稱加密算法。

常用對稱加密算法

DES

Data Encryption Standard
初代對稱加密算法
從98年開始不斷被破解，到現在已經完全不具備安全性了。
現在基本沒人用了，但很值得學習。
秘鑰長度56位

3DES

由于DES算法長度不夠，衍生出2重DES算法，3重DES算法，4重DES算法等。
用的最多的是3重DES算法。
3重DES，秘鑰長度增加，迭代次數增加。
秘鑰長度112或168，默認168。

AES

由于3DES效率有些低，所以又有了AES加密算法。
AES是目前使用最多的對稱加密算法。而且至今未被破解。
常用于移動通信系統加密和一些基于SSH協議的軟件（SSH Client、secureCRT）。
AES秘鑰長度128或192或256，默認128。
額外注意，用JDK的實現中，使用256位秘鑰需要獲得無政府限制權限文件（美國政府的限制，所以一般場景不用）。

PEB

PBE（password based encryption），基于口令的加密算法。
PBE算法，其實是對之前的AES、DES的包裝升級。
口令一般是用戶自己創建管理的。為了防止暴力破解，要對口令進行加鹽操作。
常用的PEB算法：
PBEWithMD5AndDES，秘鑰長度56位
PBEWithMD5AndTripleDES，秘鑰長度112、168位，默認168位
PBEWithSHA1AndDESede，秘鑰長度112、168位，默認168位
PBEWithSHA1AndRC2_40，秘鑰長度40~1024位（8的倍數），默認128位

常用對稱加密算法的java實現

DES實現

import org.apache.commons.codec.binary.Hex;import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.DESKeySpec; import java.security.NoSuchAlgorithmException; import java.security.SecureRandom;/*** @Author: zhangshuai* @Date: 2020-04-22 22:38* @Description:**/ public class DESTest {public static void main(String[] args) throws Exception {String name = "hello word";String password = getPassword(); // String password = "1122334455667788";System.out.println("秘鑰："+password);byte[] encrypt = encrypt(name.getBytes(), password);String encryptString = Hex.encodeHexString(encrypt);System.out.println("秘鑰加密后的密文："+encryptString);byte[] decodeHex = Hex.decodeHex(encryptString.toCharArray());byte[] decrypt = decrypt(decodeHex, password);System.out.println("秘鑰解密后的明文："+new String(decrypt));}/*** 獲取隨機秘鑰*/public static String getPassword() throws NoSuchAlgorithmException {KeyGenerator keyGenerator = KeyGenerator.getInstance("DES");keyGenerator.init(56);SecretKey secretKey = keyGenerator.generateKey();byte[] keyEncoded = secretKey.getEncoded();return Hex.encodeHexString(keyEncoded);}/*** 加密*/public static byte[] encrypt(byte[] datasource, String password) {try{SecureRandom random = new SecureRandom();DESKeySpec desKey = new DESKeySpec(password.getBytes());//密匙工廠SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");SecretKey securekey = keyFactory.generateSecret(desKey);//Cipher對象實際完成加密操作Cipher cipher = Cipher.getInstance("DES");//用密匙初始化Cipher對象cipher.init(Cipher.ENCRYPT_MODE, securekey, random);//現在，獲取數據并加密//正式執行加密操作return cipher.doFinal(datasource);}catch(Throwable e){e.printStackTrace();}return null;}/*** 解密*/public static byte[] decrypt(byte[] src, String password) throws Exception {// DES算法要求有一個可信任的隨機數源SecureRandom random = new SecureRandom();// 創建一個DESKeySpec對象DESKeySpec desKey = new DESKeySpec(password.getBytes());// 密匙工廠SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");// 將DESKeySpec對象轉換成SecretKey對象SecretKey securekey = keyFactory.generateSecret(desKey);// Cipher對象實際完成解密操作Cipher cipher = Cipher.getInstance("DES");// 用密匙初始化Cipher對象cipher.init(Cipher.DECRYPT_MODE, securekey, random);// 解密return cipher.doFinal(src);} }

3DES實現

import org.apache.commons.codec.binary.Hex;import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.DESedeKeySpec; import java.security.Key; import java.security.NoSuchAlgorithmException;public class Test3DES {public static void main(String[] args) throws Exception {String name = "hello word";byte[] password = getPassword();System.out.println("秘鑰：" + Hex.encodeHexString(password));byte[] encrypt = encrypt(name.getBytes(), password);String encryptString = Hex.encodeHexString(encrypt);System.out.println("秘鑰加密后的密文：" + encryptString);byte[] decodeHex = Hex.decodeHex(encryptString.toCharArray());byte[] decrypt = decrypt(decodeHex, password);System.out.println("秘鑰解密后的明文：" + new String(decrypt));}/*** 獲取隨機秘鑰*/public static byte[] getPassword() throws NoSuchAlgorithmException {KeyGenerator keyGenerator = KeyGenerator.getInstance("DESede");keyGenerator.init(168);SecretKey secretKey = keyGenerator.generateKey();byte[] keyEncoded = secretKey.getEncoded();return keyEncoded;}/*** 秘鑰轉換為DESede專用密鑰*/private static Key getSecretKey(byte[] key) {try {DESedeKeySpec deSedeKeySpec = new DESedeKeySpec(key);SecretKeyFactory factory = SecretKeyFactory.getInstance("DESede");Key secretKey = factory.generateSecret(deSedeKeySpec);return secretKey;} catch (Exception ex) {ex.printStackTrace();}return null;}/*** 加密*/public static byte[] encrypt(byte[] datasource, byte[] password) {try {Cipher cipher = Cipher.getInstance("DESede/ECB/PKCS5Padding");// 創建密碼器cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));// 初始化為加密模式的密碼器byte[] result = cipher.doFinal(datasource);// 加密return result;} catch (Exception ex) {ex.printStackTrace();}return null;}/*** 解密*/public static byte[] decrypt(byte[] src, byte[] password) {try {// 實例化Cipher cipher = Cipher.getInstance("DESede/ECB/PKCS5Padding");cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));byte[] result = cipher.doFinal(src);return result;} catch (Exception ex) {ex.printStackTrace();}return null;} }

AES實現

import org.apache.commons.codec.binary.Hex;import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.spec.SecretKeySpec; import java.security.Key; import java.security.NoSuchAlgorithmException;public class TestAES {public static void main(String[] args) throws Exception {String name = "hello word";byte[] password = getPassword();System.out.println("秘鑰：" + Hex.encodeHexString(password));byte[] encrypt = encrypt(name.getBytes(), password);String encryptString = Hex.encodeHexString(encrypt);System.out.println("秘鑰加密后的密文：" + encryptString);byte[] decodeHex = Hex.decodeHex(encryptString.toCharArray());byte[] decrypt = decrypt(decodeHex, password);System.out.println("秘鑰解密后的明文：" + new String(decrypt));}/*** 獲取隨機秘鑰*/public static byte[] getPassword() throws NoSuchAlgorithmException {KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");keyGenerator.init(128);SecretKey secretKey = keyGenerator.generateKey();byte[] keyEncoded = secretKey.getEncoded();return keyEncoded;}/*** 獲取專用密鑰*/private static Key getSecretKey(byte[] key) {try {return new SecretKeySpec(key, "AES");} catch (Exception ex) {ex.printStackTrace();}return null;}/*** 加密*/public static byte[] encrypt(byte[] datasource, byte[] password) {try {Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");// 創建密碼器cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));// 初始化為加密模式的密碼器byte[] result = cipher.doFinal(datasource);// 加密return result;} catch (Exception ex) {ex.printStackTrace();}return null;}/*** 解密*/public static byte[] decrypt(byte[] src, byte[] password) {try {// 實例化Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));byte[] result = cipher.doFinal(src);return result;} catch (Exception ex) {ex.printStackTrace();}return null;}

PEB實現

import org.apache.commons.codec.binary.Hex;import javax.crypto.Cipher; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.PBEKeySpec; import javax.crypto.spec.PBEParameterSpec; import java.security.Key; import java.security.SecureRandom;public class TestPBE {public static void main(String[] args) throws Exception {String name = "hello word";String password = "123456";System.out.println("秘鑰：" + password);PBEParameterSpec salt = getSalt();byte[] encrypt = encrypt(name.getBytes(), password, salt);String encryptString = Hex.encodeHexString(encrypt);System.out.println("秘鑰加密后的密文：" + encryptString);byte[] decrypt = decrypt(encrypt, password, salt);System.out.println("秘鑰解密后的明文：" + new String(decrypt));}/*** 獲取專用密鑰*/private static Key getSecretKey(String password) {try {PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray());SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWITHMD5andDES");return factory.generateSecret(pbeKeySpec);} catch (Exception ex) {ex.printStackTrace();}return null;}/*** 獲取鹽*/private static PBEParameterSpec getSalt() {SecureRandom secureRandom = new SecureRandom();byte[] salt = secureRandom.generateSeed(8);// 100次加鹽迭代return new PBEParameterSpec(salt, 100);}/*** 加密*/public static byte[] encrypt(byte[] datasource, String password, PBEParameterSpec salt) {try {Cipher cipher = Cipher.getInstance("PBEWITHMD5andDES");// 創建密碼器cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password), salt);// 初始化為加密模式的密碼器byte[] result = cipher.doFinal(datasource);// 加密return result;} catch (Exception ex) {ex.printStackTrace();}return null;}/*** 解密*/public static byte[] decrypt(byte[] src, String password, PBEParameterSpec salt) {try {// 實例化Cipher cipher = Cipher.getInstance("PBEWITHMD5andDES");cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password), salt);byte[] result = cipher.doFinal(src);return result;} catch (Exception ex) {ex.printStackTrace();}return null;}

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