<?php

/**
 * 企业微信回调消息加解密示例代码.
 *
 * @copyright Copyright (c) 1998-2014 Tencent Inc.
 */


include_once "sha1.php";
include_once "xmlparse.php";
include_once "pkcs7Encoder.php";
include_once "errorCode.php";

class WXBizMsgCrypt
{
	private $m_sToken;
	private $m_sEncodingAesKey;
	private $m_sReceiveId;

	/**
	 * 构造函数
	 * @param $token string 开发者设置的token
	 * @param $encodingAesKey string 开发者设置的EncodingAESKey
	 * @param $receiveId string, 不同应用场景传不同的id
	 */
	public function __construct($token, $encodingAesKey, $receiveId)
	{
		$this->m_sToken = $token;
		$this->m_sEncodingAesKey = $encodingAesKey;
		$this->m_sReceiveId = $receiveId;
	}
	
    /*
	*验证URL
    *@param sMsgSignature: 签名串，对应URL参数的msg_signature
    *@param sTimeStamp: 时间戳，对应URL参数的timestamp
    *@param sNonce: 随机串，对应URL参数的nonce
    *@param sEchoStr: 随机串，对应URL参数的echostr
    *@param sReplyEchoStr: 解密之后的echostr，当return返回0时有效
    *@return：成功0，失败返回对应的错误码
	*/
	public function VerifyURL($sMsgSignature, $sTimeStamp, $sNonce, $sEchoStr, &$sReplyEchoStr)
	{
		if (strlen($this->m_sEncodingAesKey) != 43) {
			return ErrorCode::$IllegalAesKey;
		}

		$pc = new Prpcrypt($this->m_sEncodingAesKey);
		//verify msg_signature
		$sha1 = new SHA1;
		$array = $sha1->getSHA1($this->m_sToken, $sTimeStamp, $sNonce, $sEchoStr);
		$ret = $array[0];

		if ($ret != 0) {
			return $ret;
		}

		$signature = $array[1];
		if ($signature != $sMsgSignature) {
			return ErrorCode::$ValidateSignatureError;
		}

		$result = $pc->decrypt($sEchoStr, $this->m_sReceiveId);
		if ($result[0] != 0) {
			return $result[0];
		}
		$sReplyEchoStr = $result[1];

		return ErrorCode::$OK;
	}
	/**
	 * 将公众平台回复用户的消息加密打包.
	 * <ol>
	 *    <li>对要发送的消息进行AES-CBC加密</li>
	 *    <li>生成安全签名</li>
	 *    <li>将消息密文和安全签名打包成xml格式</li>
	 * </ol>
	 *
	 * @param $replyMsg string 公众平台待回复用户的消息，xml格式的字符串
	 * @param $timeStamp string 时间戳，可以自己生成，也可以用URL参数的timestamp
	 * @param $nonce string 随机串，可以自己生成，也可以用URL参数的nonce
	 * @param &$encryptMsg string 加密后的可以直接回复用户的密文，包括msg_signature, timestamp, nonce, encrypt的xml格式的字符串,
	 *                      当return返回0时有效
	 *
	 * @return int 成功0，失败返回对应的错误码
	 */
	public function EncryptMsg($sReplyMsg, $sTimeStamp, $sNonce, &$sEncryptMsg)
	{
		$pc = new Prpcrypt($this->m_sEncodingAesKey);

		//加密
		$array = $pc->encrypt($sReplyMsg, $this->m_sReceiveId);
		$ret = $array[0];
		if ($ret != 0) {
			return $ret;
		}

		if ($sTimeStamp == null) {
			$sTimeStamp = time();
		}
		$encrypt = $array[1];

		//生成安全签名
		$sha1 = new SHA1;
		$array = $sha1->getSHA1($this->m_sToken, $sTimeStamp, $sNonce, $encrypt);
		$ret = $array[0];
		if ($ret != 0) {
			return $ret;
		}
		$signature = $array[1];

		//生成发送的xml
		$xmlparse = new XMLParse;
		$sEncryptMsg = $xmlparse->generate($encrypt, $signature, $sTimeStamp, $sNonce);
		return ErrorCode::$OK;
	}


	/**
	 * 检验消息的真实性，并且获取解密后的明文.
	 * <ol>
	 *    <li>利用收到的密文生成安全签名，进行签名验证</li>
	 *    <li>若验证通过，则提取xml中的加密消息</li>
	 *    <li>对消息进行解密</li>
	 * </ol>
	 *
	 * @param $msgSignature string 签名串，对应URL参数的msg_signature
	 * @param $timestamp string 时间戳 对应URL参数的timestamp
	 * @param $nonce string 随机串，对应URL参数的nonce
	 * @param $postData string 密文，对应POST请求的数据
	 * @param &$msg string 解密后的原文，当return返回0时有效
	 *
	 * @return int 成功0，失败返回对应的错误码
	 */
	public function DecryptMsg($sMsgSignature, $sTimeStamp = null, $sNonce, $sPostData, &$sMsg)
	{
		if (strlen($this->m_sEncodingAesKey) != 43) {
			return ErrorCode::$IllegalAesKey;
		}

		$pc = new Prpcrypt($this->m_sEncodingAesKey);

		//提取密文
		$xmlparse = new XMLParse;
		$array = $xmlparse->extract($sPostData);
		$ret = $array[0];

		if ($ret != 0) {
			return $ret;
		}

		if ($sTimeStamp == null) {
			$sTimeStamp = time();
		}

		$encrypt = $array[1];

		//验证安全签名
		$sha1 = new SHA1;
		$array = $sha1->getSHA1($this->m_sToken, $sTimeStamp, $sNonce, $encrypt);
		$ret = $array[0];

		if ($ret != 0) {
			return $ret;
		}

		$signature = $array[1];
		if ($signature != $sMsgSignature) {
			return ErrorCode::$ValidateSignatureError;
		}

		$result = $pc->decrypt($encrypt, $this->m_sReceiveId);
		if ($result[0] != 0) {
			return $result[0];
		}
		$sMsg = $result[1];

		return ErrorCode::$OK;
	}

}