WXBizMsgCrypt.cpp

#include "WXBizMsgCrypt.h"

#include <cstring>
#include <cstdlib>
#include <arpa/inet.h>
#include <string>
#include <vector>
#include <algorithm>
#include <iostream>

#include "openssl/aes.h"
#include "openssl/sha.h"
#include "openssl/evp.h"


#define FREE_PTR(ptr) \
    if (NULL != (ptr)) {\
        free (ptr);\
        (ptr) = NULL;\
    }

#define DELETE_PTR(ptr) \
    if (NULL != (ptr)) {\
        delete (ptr);\
        (ptr) = NULL;\
    }
    
namespace Tencent{

int WXBizMsgCrypt::VerifyURL(const std::string &sMsgSignature,
				const std::string &sTimeStamp,
				const std::string &sNonce,
				const std::string &sEchoStr,
				std::string &sReplyEchoStr)
{
	if(0 != ValidateSignature(sMsgSignature,sTimeStamp,sNonce,sEchoStr) ) 
    {
        return WXBizMsgCrypt_ValidateSignature_Error;
    }

    //1.decode base64
    std::string sAesData;
    if(0 != DecodeBase64(sEchoStr,sAesData))
    {
        return WXBizMsgCrypt_DecodeBase64_Error;
    }
    
    //2.decode aes
    std::string sAesKey;
    std::string sNoEncryptData;
    if(0 != GenAesKeyFromEncodingKey(m_sEncodingAESKey,sAesKey)) 
    {
        return WXBizMsgCrypt_IllegalAesKey;
    }
    if(0 != AES_CBCDecrypt(sAesData, sAesKey, &sNoEncryptData))
    {
        return WXBizMsgCrypt_DecryptAES_Error;
    }

    // 3. remove kRandEncryptStrLen str 
    if(sNoEncryptData.size() <= (kRandEncryptStrLen + kMsgLen))
    {
        return WXBizMsgCrypt_IllegalBuffer;
    }  
    uint32_t iNetLen = *((const uint32_t *)(sNoEncryptData.c_str() + kRandEncryptStrLen));
    uint32_t iMsgLen = ntohl(iNetLen);
    if(sNoEncryptData.size() < (kRandEncryptStrLen + kMsgLen + iMsgLen))
    {
        return WXBizMsgCrypt_IllegalBuffer;
    }
    sReplyEchoStr = sNoEncryptData.substr(kRandEncryptStrLen+kMsgLen,iMsgLen );

    //4. validate Corpid
    std::string sReceiveId = sNoEncryptData.substr(kRandEncryptStrLen+kMsgLen+iMsgLen);
    if(sReceiveId != m_sReceiveId)
    {
        return WXBizMsgCrypt_ValidateCorpid_Error;
    }
   
    return WXBizMsgCrypt_OK;

}

int WXBizMsgCrypt::DecryptMsg(const std::string &sMsgSignature,
                const std::string &sTimeStamp,
                const std::string &sNonce,
                const std::string &sPostData,
                std::string &sMsg)
{
    //1.validate xml format
    std::string sEncryptMsg;
    if(0 != GetXmlField(sPostData,"Encrypt",sEncryptMsg))
    {
        return WXBizMsgCrypt_ParseXml_Error;
    }

    //2.validate signature
    if(0 != ValidateSignature(sMsgSignature,sTimeStamp,sNonce,sEncryptMsg) ) 
    {
        return WXBizMsgCrypt_ValidateSignature_Error;
    }

    //3.decode base64
    std::string sAesData;
    if(0 != DecodeBase64(sEncryptMsg,sAesData))
    {
        return WXBizMsgCrypt_DecodeBase64_Error;
    }
    
    //4.decode aes
    std::string sAesKey;
    std::string sNoEncryptData;
    if(0 != GenAesKeyFromEncodingKey(m_sEncodingAESKey,sAesKey)) 
    {
        return WXBizMsgCrypt_IllegalAesKey;
    }
    if(0 != AES_CBCDecrypt(sAesData, sAesKey, &sNoEncryptData))
    {
        return WXBizMsgCrypt_DecryptAES_Error;
    }

    // 5. remove kRandEncryptStrLen str 
    if(sNoEncryptData.size() <= (kRandEncryptStrLen + kMsgLen))
    {
        return WXBizMsgCrypt_IllegalBuffer;
    }  
    uint32_t iNetLen = *((const uint32_t *)(sNoEncryptData.c_str() + kRandEncryptStrLen));
    uint32_t iMsgLen = ntohl(iNetLen);
    if(sNoEncryptData.size() < (kRandEncryptStrLen + kMsgLen + iMsgLen))
    {
        return WXBizMsgCrypt_IllegalBuffer;
    }
    sMsg = sNoEncryptData.substr(kRandEncryptStrLen+kMsgLen,iMsgLen );

    //6. validate corpid
    std::string sReceiveId = sNoEncryptData.substr(kRandEncryptStrLen+kMsgLen+iMsgLen);
    if(sReceiveId != m_sReceiveId)
    {
        return WXBizMsgCrypt_ValidateCorpid_Error;
    }
   
    return WXBizMsgCrypt_OK;
}

int WXBizMsgCrypt::EncryptMsg(const std::string &sReplyMsg,
                const std::string &sTimeStamp,
                const std::string &sNonce,
                std::string &sEncryptMsg)
{
    if(0 == sReplyMsg.size())
    {
        return WXBizMsgCrypt_ParseXml_Error;
    }

    //1.add rand str ,len, corpid
    std::string sNeedEncrypt;
    GenNeedEncryptData(sReplyMsg,sNeedEncrypt);
    
    //2. AES Encrypt
    std::string sAesData;
    std::string sAesKey;
    if(0 != GenAesKeyFromEncodingKey(m_sEncodingAESKey,sAesKey)) 
    {
        return WXBizMsgCrypt_IllegalAesKey;
    }
    if(0 != AES_CBCEncrypt(sNeedEncrypt, sAesKey, &sAesData))
    {
        return WXBizMsgCrypt_EncryptAES_Error;
    }    

    //3. base64Encode
    std::string sBase64Data;
    if( 0!= EncodeBase64(sAesData,sBase64Data) )
    {
        return WXBizMsgCrypt_EncodeBase64_Error;
    }
    
    //4. compute signature
    std::string sSignature;
    if(0!=ComputeSignature(m_sToken, sTimeStamp, sNonce, sBase64Data, sSignature))
    {
        return WXBizMsgCrypt_ComputeSignature_Error;
    }
    
    //5. Gen xml
    if(0 != GenReturnXml(sBase64Data, sSignature, sTimeStamp, sNonce, sEncryptMsg) )
    {
        return WXBizMsgCrypt_GenReturnXml_Error ;
    }
    return WXBizMsgCrypt_OK;
}

int WXBizMsgCrypt::AES_CBCEncrypt( const std::string & objSource,
        const std::string & objKey, std::string * poResult )
{
    return AES_CBCEncrypt( objSource.data(), objSource.size(),
            objKey.data(), objKey.size(), poResult );
}

int WXBizMsgCrypt::AES_CBCEncrypt( const char * sSource, const uint32_t iSize,
        const char * sKey,  uint32_t iKeySize, std::string * poResult )
{
    if ( !sSource || !sKey || !poResult || iSize <= 0)
    {
        return -1;
    }
    
    poResult->clear();

    int padding = kAesKeySize - iSize % kAesKeySize;

    char * tmp = (char*)malloc( iSize + padding );
    if(NULL == tmp)
    {
        return -1;
    }
    memcpy( tmp, sSource, iSize );
    memset( tmp + iSize, padding, padding );
    
    unsigned char * out = (unsigned char*)malloc( iSize + padding );
    if(NULL == out)
    {
        FREE_PTR(tmp);
        return -1;
    }

    unsigned char key[ kAesKeySize ] = { 0 };
    unsigned char iv[ kAesIVSize ] = { 0 };
    memcpy( key, sKey, iKeySize > kAesKeySize ? kAesKeySize : iKeySize );
    memcpy(iv, key, sizeof(iv) < sizeof(key) ? sizeof(iv) : sizeof(key));

    AES_KEY aesKey;
    AES_set_encrypt_key( key, 8 * kAesKeySize, &aesKey );
    AES_cbc_encrypt((unsigned char *)tmp, out,iSize + padding,  &aesKey, iv, AES_ENCRYPT);
    poResult->append((char*)out, iSize + padding);
    
    FREE_PTR(tmp);
    FREE_PTR(out);
    return 0;
}

int WXBizMsgCrypt::AES_CBCDecrypt( const std::string & objSource,
        const std::string & objKey, std::string * poResult )
{
    return AES_CBCDecrypt( objSource.data(), objSource.size(),
            objKey.data(), objKey.size(), poResult );
}

int WXBizMsgCrypt::AES_CBCDecrypt( const char * sSource, const uint32_t iSize,
        const char * sKey, uint32_t iKeySize, std::string * poResult )
{
    if ( !sSource || !sKey || iSize < kAesKeySize || iSize % kAesKeySize != 0 || !poResult)
    {
        return -1;
    }
    
    poResult->clear();

    unsigned char * out = (unsigned char*)malloc( iSize );
    if(NULL == out)
    {
        return -1;
    }

    unsigned char key[ kAesKeySize ] = { 0 };
    unsigned char iv[ kAesIVSize ] = {0} ;
    memcpy( key, sKey, iKeySize > kAesKeySize ? kAesKeySize : iKeySize );
    memcpy(iv, key, sizeof(iv) < sizeof(key) ? sizeof(iv) : sizeof(key));

    int iReturnValue = 0;
    AES_KEY aesKey;
    AES_set_decrypt_key( key, 8 * kAesKeySize, &aesKey );
    AES_cbc_encrypt( (unsigned char *)sSource, out, iSize, &aesKey, iv ,AES_DECRYPT);
    if( out[iSize-1] > 0 && out[iSize-1] <= kAesKeySize && (iSize - out[iSize-1]) > 0 )
    {
        poResult->append( (char *)out , iSize - out[iSize-1] );
    } else {
        iReturnValue = -1;
    }

    FREE_PTR(out);
    return iReturnValue;
}

int WXBizMsgCrypt::EncodeBase64(const std::string sSrc, std::string & sTarget)
{
    if(0 == sSrc.size() || kMaxBase64Size < sSrc.size())
    {
        return -1;
    }
    
    uint32_t iBlockNum = sSrc.size() / 3;
    if (iBlockNum * 3 != sSrc.size())
    {
        iBlockNum++;
    }
    uint32_t iOutBufSize = iBlockNum * 4 + 1;
    
    char * pcOutBuf = (char*)malloc( iOutBufSize);
    if(NULL == pcOutBuf)
    {
        return -1;
    }
    int iReturn = 0;
    int ret = EVP_EncodeBlock((unsigned char*)pcOutBuf, (const unsigned char*)sSrc.c_str(), sSrc.size());
    if (ret > 0 && ret < (int)iOutBufSize)
    {
        sTarget.assign(pcOutBuf,ret);
    }
    else
    {
        iReturn = -1;
    }
    
    FREE_PTR(pcOutBuf);
    return iReturn;
}


int WXBizMsgCrypt::DecodeBase64(const std::string sSrc, std::string & sTarget)
{
    if(0 == sSrc.size() || kMaxBase64Size < sSrc.size())
    {
        return -1;
    }
    
    //计算末尾=号个数
    int iEqualNum = 0;
    for(int n= sSrc.size() - 1; n>=0; --n)
    {
        if(sSrc.c_str()[n] == '=')
        {
            iEqualNum++;
        }
        else
        {
            break;
        }
    }
    
    int iOutBufSize = sSrc.size();
    char * pcOutBuf = (char*)malloc( iOutBufSize);
    if(NULL == pcOutBuf)
    {
        return -1;
    }
    
    int iRet = 0;
    int iTargetSize = 0;
    iTargetSize =  EVP_DecodeBlock((unsigned char*)pcOutBuf, (const unsigned char*)sSrc.c_str(), sSrc.size());
    if(iTargetSize > iEqualNum && iTargetSize < iOutBufSize)
    {
        sTarget.assign(pcOutBuf, iTargetSize - iEqualNum);
    }
    else
    {
        iRet = -1;
    }
    
    FREE_PTR(pcOutBuf);
    return iRet;
}

int WXBizMsgCrypt::ComputeSignature(const std::string sToken, const std::string sTimeStamp, const std::string & sNonce,
    const std::string & sMessage, std::string & sSignature)
{
    if( 0 == sToken.size() || 0 == sNonce.size() || 0 == sMessage.size() || 0 == sTimeStamp.size())
    {
        return -1;
    }

    //sort
    std::vector< std::string >  vecStr;
    vecStr.push_back( sToken );
    vecStr.push_back( sTimeStamp );
    vecStr.push_back( sNonce );
    vecStr.push_back( sMessage );
    std::sort( vecStr.begin(), vecStr.end() );
    std::string sStr = vecStr[0] + vecStr[1] + vecStr[2] + vecStr[3] ;

    //compute
    unsigned char output[SHA_DIGEST_LENGTH] = { 0 };
    if( NULL == SHA1( (const unsigned char *)sStr.c_str(), sStr.size(), output ) )
    {
        return -1;
    }

    // to hex
    sSignature.clear();
    char tmpChar[ 8 ] = { 0 };
    for( int i = 0; i < SHA_DIGEST_LENGTH; i++ )
    {
        snprintf( tmpChar, sizeof( tmpChar ), "%02x", 0xff & output[i] );
        sSignature.append( tmpChar );
    }
    return 0;    
}


int WXBizMsgCrypt::ValidateSignature(const std::string &sMsgSignature, const std::string &sTimeStamp, 
    const std::string &sNonce, const std::string & sEncryptMsg)
{
    std::string sSignature;
    if(0 != ComputeSignature(m_sToken, sTimeStamp, sNonce, sEncryptMsg, sSignature))
    {
        return -1;
    }
    
    if( sMsgSignature != sSignature)
    {
        return -1;
    }
    
    return 0;
}

int WXBizMsgCrypt::GenAesKeyFromEncodingKey( const std::string & sEncodingKey, std::string & sAesKey)
{
    if(kEncodingKeySize != sEncodingKey.size())
    {
        return -1;
    }
    
    std::string sBase64 = sEncodingKey + "=";
    int ret = DecodeBase64(sBase64, sAesKey);
    if(0 != ret || kAesKeySize != sAesKey.size())
    {
        return -1;
    }
    
    return 0;
}

int WXBizMsgCrypt::GetXmlField(const std::string & sPostData, const std::string & sField, std::string &sEncryptMsg)
{
    tinyxml2::XMLDocument xmlDoc;
    if(tinyxml2::XML_SUCCESS != xmlDoc.Parse(sPostData.c_str(), sPostData.size()))
    {
        return -1;
    }
    
    tinyxml2::XMLElement * xmlElement = xmlDoc.FirstChildElement("xml");
    if(NULL == xmlElement)
    {
        return -1;
    }
    
    tinyxml2::XMLElement * msgElement = xmlElement->FirstChildElement(sField.c_str());
    if(NULL == msgElement)
    {
        return -1;
    }
    
    const char* pMsgBuf = msgElement->GetText();
    if(NULL == pMsgBuf)
    {
        return -1;
    }    
    
    sEncryptMsg = pMsgBuf;
    return 0;
}
void WXBizMsgCrypt::GenRandStr(std::string & sRandStr, uint32_t len)
{
    uint32_t idx = 0;
    srand((unsigned)time(NULL));
    char tempChar = 0;
    sRandStr.clear();
    
    while(idx < len)
    {
        tempChar = rand()%128;
        if(isprint(tempChar))
        {
            sRandStr.append(1, tempChar);
            ++idx;
        }
    }
}

void WXBizMsgCrypt::GenNeedEncryptData(const std::string &sReplyMsg,std::string & sNeedEncrypt )
{
    //random(16B)+ msg_len(4B) + msg + $corpid
    std::string sRandStr;
    GenRandStr(sRandStr,kRandEncryptStrLen);
    uint32_t iXmlSize = sReplyMsg.size();
    uint32_t iNSize  = htonl(iXmlSize);
    std::string sSize ;
    sSize.assign((const char *)&iNSize,sizeof(iNSize));
    
    sNeedEncrypt.erase();
    sNeedEncrypt = sRandStr;
    sNeedEncrypt += sSize;
    sNeedEncrypt += sReplyMsg;
    sNeedEncrypt += m_sReceiveId;
}

int WXBizMsgCrypt::SetOneFieldToXml(tinyxml2::XMLDocument * pDoc, tinyxml2::XMLNode* pXmlNode, const char * pcFieldName, 
    const std::string & value, bool bIsCdata)
{
    if(!pDoc || !pXmlNode || !pcFieldName)
    {
        return -1;
    }
    
    tinyxml2::XMLElement * pFiledElement = pDoc->NewElement(pcFieldName);  
    if(NULL == pFiledElement)
    {
        return -1;
    }
    
    tinyxml2::XMLText * pText = pDoc->NewText(value.c_str()); 
    if(NULL == pText)
    {
        return -1;
    }
    
    pText->SetCData(bIsCdata);
    pFiledElement->LinkEndChild(pText);  
    
    pXmlNode->LinkEndChild(pFiledElement);  
    return 0;
}

int WXBizMsgCrypt::GenReturnXml(const std::string & sEncryptMsg, const std::string & sSignature, const std::string & sTimeStamp, 
    const std::string & sNonce, std::string & sResult)
{
    tinyxml2::XMLPrinter oPrinter;
    tinyxml2::XMLNode* pXmlNode = NULL;
    tinyxml2::XMLDocument * pDoc = new tinyxml2::XMLDocument();
    if(NULL == pDoc)
    {
        return -1;
    }
    
    pXmlNode = pDoc->InsertEndChild( pDoc->NewElement( "xml" ) );
    if(NULL == pXmlNode)
    {
        DELETE_PTR(pDoc);
        return -1;
    }

    if(0 != SetOneFieldToXml(pDoc,pXmlNode,"Encrypt",sEncryptMsg,true))
    {
        DELETE_PTR(pDoc);
        return -1;
    }

    if(0 != SetOneFieldToXml(pDoc,pXmlNode,"MsgSignature",sSignature,true))
    {
        DELETE_PTR(pDoc);
        return -1;
    }

    if(0 != SetOneFieldToXml(pDoc,pXmlNode,"TimeStamp",sTimeStamp,true))
    {
        DELETE_PTR(pDoc);
        return -1;
    }

    if(0 != SetOneFieldToXml(pDoc,pXmlNode,"Nonce",sNonce,true))
    {
        DELETE_PTR(pDoc);
        return -1;
    }

    //转成string
    pDoc->Accept(&oPrinter);
    sResult = oPrinter.CStr();
    
    DELETE_PTR(pDoc);
    return 0;    
}

}