PHP与Java之间AES/GCM/128加密解密的跨平台实现指南

<?php
function aes_gcm_decrypt($content, $secret) {
    $cipher = 'aes-128-gcm';
    // Base64解码后得到二进制数据，再转换为十六进制字符串以便解析
    $ciphertextwithiv = bin2hex(base64_decode($content));
    // 从十六进制字符串中提取IV (24字符 = 12字节)
    $iv = substr($ciphertextwithiv, 0, 24);
    // 从十六进制字符串中提取Tag (32字符 = 16字节)
    $tag = substr($ciphertextwithiv , -32, 32);
    // 密文是IV和Tag之间的部分
    $ciphertext = substr($ciphertextwithiv, 24, strlen($ciphertextwithiv) - 24 - 32);
    // 密钥从十六进制字符串转换为二进制
    $skey = hex2bin($secret);

    // 使用openssl_decrypt进行解密
    return openssl_decrypt(hex2bin($ciphertext), $cipher, $skey, OPENSSL_RAW_DATA, hex2bin($iv), hex2bin($tag));
}

function aes_gcm_encrypt($data, $secret) {
  $cipher = 'aes-128-gcm';
  $string = is_array($data) ? json_encode($data) : $data;
  // 密钥从十六进制字符串转换为二进制
  $skey = hex2bin($secret);
  // 生成12字节的随机IV (AES/GCM/128的IV长度通常为12字节)
  $iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length($cipher));

  $tag = NULL; // Tag将通过引用传递给openssl_encrypt
  // 执行加密，Tag会填充到$tag变量中
  $content = openssl_encrypt($string, $cipher, $skey, OPENSSL_RAW_DATA, $iv, $tag);

  // 组合IV、密文和Tag，全部转换为十六进制字符串，然后转换为二进制，最后进行Base64编码
  $str = bin2hex($iv) . bin2hex($content) . bin2hex($tag);
  return base64_encode(hex2bin($str));
}

// 示例用法
$content = 'Test text.{123456}';
$secret = '544553534B4559313233343536'; // 24个十六进制字符，对应12字节
$encryptStr = aes_gcm_encrypt($content, $secret);
print_r("encrypt -> $encryptStr \n");

$decryptStr = aes_gcm_decrypt($encryptStr, $secret);
print_r("decrypt -> $decryptStr \n");

import java.security.spec.KeySpec;
import java.util.Base64;
import java.util.Random;
import javax.crypto.*;
import javax.crypto.spec.*;

public class MyTest {

    public static void main(String[] args) throws Exception {
        String secret = "544553534B4559313233343536";
        String encryptStr = "Fun3yZTPcHsxBpft+jBZDe2NjGNAs8xUHY21eZswZE4iLKYdBsyER7RwVfFvuQ==";
        String decryptString = decrypt(encryptStr, secret, 16); // 这里的16是IV长度
        System.out.println("decryptString: " + decryptString);
    }

    private static String decrypt(String data, String mainKey, int ivLength) throws Exception {
        final byte[] encryptedBytes = Base64.getDecoder().decode(data.getBytes("UTF8"));
        final byte[] initializationVector = new byte[ivLength]; // IV长度被设置为16
        System.arraycopy(encryptedBytes, 0, initializationVector, 0, ivLength);
        // 密钥派生方式与PHP不一致，PHP直接将十六进制字符串转换为二进制密钥
        SecretKeySpec secretKeySpec = new SecretKeySpec(generateSecretKeyFromPassword(mainKey, mainKey.length()), "AES");
        // GCMParameterSpec的Tag长度128位正确，但IV长度不正确
        GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, initializationVector);
        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
        cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, gcmParameterSpec);
        // 传入doFinal的数据包含密文和Tag，但IV长度错误会影响偏移量
        return new String(cipher.doFinal(encryptedBytes, ivLength, encryptedBytes.length - ivLength), "UTF8");
    }

    // 密钥派生函数，与PHP的hex2bin行为不一致
    private static byte[] generateSecretKeyFromPassword(String password, int keyLength) throws Exception {
        byte[] salt = new byte[keyLength];
        new Random(password.hashCode()).nextBytes(salt);
        SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
        KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 65536, 128);
        return factory.generateSecret(spec).getEncoded();
    }
}