java使用教程怎样实现简单的加密解密功能 java使用教程的加密操作基础技巧​

javax.crypto

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

public class SimpleAES {

    // AES算法名，通常会带上模式和填充方式，例如 "AES/ECB/PKCS5Padding"
    private static final String ALGORITHM = "AES";
    private static final String TRANSFORMATION = "AES/ECB/PKCS5Padding"; // ECB模式简单，但实际应用中推荐CBC等

    /**
     * 生成AES密钥
     * @return SecretKey对象
     * @throws Exception
     */
    public static SecretKey generateAESKey() throws Exception {
        KeyGenerator keyGen = KeyGenerator.getInstance(ALGORITHM);
        keyGen.init(128); // AES支持128, 192, 256位密钥
        return keyGen.generateKey();
    }

    /**
     * 加密数据
     * @param data 待加密的原始数据
     * @param key 用于加密的密钥
     * @return 加密后的Base64编码字符串
     * @throws Exception
     */
    public static String encrypt(String data, SecretKey key) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byte[] encryptedBytes = cipher.doFinal(data.getBytes(StandardCharsets.UTF_8));
        return Base64.getEncoder().encodeToString(encryptedBytes);
    }

    /**
     * 解密数据
     * @param encryptedData 加密后的Base64编码字符串
     * @param key 用于解密的密钥
     * @return 解密后的原始数据
     * @throws Exception
     */
    public static String decrypt(String encryptedData, SecretKey key) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.DECRYPT_MODE, key);
        byte[] decryptedBytes = cipher.doFinal(Base64.getDecoder().decode(encryptedData));
        return new String(decryptedBytes, StandardCharsets.UTF_8);
    }

    public static void main(String[] args) {
        try {
            SecretKey aesKey = generateAESKey();
            // 实际应用中，你可能需要将密钥保存或传输，这里为了演示直接使用
            // 将SecretKey转换为字节数组，方便存储或传输
            byte[] keyBytes = aesKey.getEncoded();
            // 从字节数组恢复SecretKey
            SecretKey restoredKey = new SecretKeySpec(keyBytes, ALGORITHM);


            String originalText = "这是一段需要加密的秘密信息。";
            System.out.println("原始文本: " + originalText);

            String encryptedText = encrypt(originalText, restoredKey);
            System.out.println("加密后: " + encryptedText);

            String decryptedText = decrypt(encryptedText, restoredKey);
            System.out.println("解密后: " + decryptedText);

            // 尝试用错误的密钥解密，会抛出BadPaddingException
            // SecretKey wrongKey = generateAESKey();
            // String wrongDecrypted = decrypt(encryptedText, wrongKey);
            // System.out.println("错误密钥解密: " + wrongDecrypted);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

KeyGenerator

Cipher

SecretKey

byte[]

SecretKeySpec

main

keyBytes

aesKey

KeyStore