java 加密 解密 工具类

### Java 加密解密工具类示例 #### EncryptUtils 类实现 `EncryptUtils` 是一个自定义的 Java 工具类，用于封装常见的加密和解密算法，如 MD5、SHA-1、SHA-256、AES 和 DES 等。该工具类提供了简单易用的接口，使开发者能够方便地进行数据的加密、解密、签名和验证操作。 ```java import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.spec.SecretKeySpec; import java.security.MessageDigest; import java.util.Base64; public class EncryptUtils { private static final String ALGORITHM_AES = "AES"; private static final int KEY_SIZE = 128; // Key size can be 128, 192 or 256 bits depending on the algorithm and environment. /** * Generate a new secret key for AES encryption. */ public static SecretKey generateKey() throws Exception { KeyGenerator keyGen = KeyGenerator.getInstance(ALGORITHM_AES); keyGen.init(KEY_SIZE); return keyGen.generateKey(); } /** * Convert string to Base64 encoded string using given key. */ public static String encrypt(String data, SecretKey secret) throws Exception { Cipher cipher = Cipher.getInstance(ALGORITHM_AES); cipher.init(Cipher.ENCRYPT_MODE, secret); byte[] encryptedData = cipher.doFinal(data.getBytes()); return Base64.getEncoder().encodeToString(encryptedData); } /** * Decrypt Base64 encoded string back into original string using given key. */ public static String decrypt(String encryptedData, SecretKey secret) throws Exception { Cipher cipher = Cipher.getInstance(ALGORITHM_AES); cipher.init(Cipher.DECRYPT_MODE, secret); byte[] decodedValue = Base64.getDecoder().decode(encryptedData); byte[] decryptedData = cipher.doFinal(decodedValue); return new String(decryptedData); } } ``` 此代码片段展示了如何创建 `EncryptUtils` 类并实现了基本的 AES 加密/解密功能[^2]。 #### 使用示例 下面是如何使用上述工具类来进行字符串的加密与解密： ```java try { // Step 1: Create an instance of SecretKey (only once per application lifecycle). SecretKey mySecretKey = EncryptUtils.generateKey(); // Store this somewhere safe as you will need it later for decryption! // Step 2: Use your generated key to perform encryption operations. String messageToBeEncrypted = "This is a test."; System.out.println("Original Message : " + messageToBeEncrypted); String encryptedMessage = EncryptUtils.encrypt(messageToBeEncrypted, mySecretKey); System.out.println("Encrypted Message: " + encryptedMessage); // Step 3: When needed, use the same key to reverse the process by performing decryption operation. String decryptedMessage = EncryptUtils.decrypt(encryptedMessage, mySecretKey); System.out.println("Decrypted Message: " + decryptedMessage); } catch (Exception e) { e.printStackTrace(); } ``` 这段程序首先生成了一个新的秘密钥，接着利用它对消息进行了加密处理，并最终成功恢复了原始的消息内容。