bool CoSignMessage(PCCERT_CONTEXT *a_CertContext, // Сертификат
				   CRYPT_DATA_BLOB *pSignedMessageBlob, // уже подписаное сообщение
				   CRYPT_DATA_BLOB *pCosignedMessageBlob, // результат - соподписаное сообщение
				   LPSTR sMsg )
{
	bool fReturn = false; 
	PCCERT_CONTEXT pCosignerCert = *a_CertContext; 
	HCRYPTPROV hCryptProv = NULL;
	HCRYPTMSG hMsg = NULL;
	DWORD cbCosignedMessageBlob;
	BYTE  *pbCosignedMessageBlob = NULL;


	// Initialize the output pointer.
	pCosignedMessageBlob->cbData = 0;
	pCosignedMessageBlob->pbData = NULL;
	DWORD dwKeySpec;
	if(!(CryptAcquireCertificatePrivateKey(
		pCosignerCert,
		0,
		NULL,
		&hCryptProv,
		&dwKeySpec,
		NULL)))
	{
		MyHandleError(
			TEXT("CryptAcquireCertificatePrivateKey failed."));
		 exit_CosignMessage(hMsg, pbCosignedMessageBlob);
	}

	// Open a message for decoding.
	if(!(hMsg = CryptMsgOpenToDecode(
		m_Encoding_Type, //MY_ENCODING_TYPE,
		0,//CMSG_DETACHED_FLAG,
		0,
		NULL,
		NULL,
		NULL)))
	{
		MyHandleError(TEXT("CryptMsgOpenToDecode failed."));
		exit_CosignMessage(hMsg, pbCosignedMessageBlob);
	}


	// Update the message with the encoded BLOB.
	if(!(CryptMsgUpdate(
		hMsg,
		pSignedMessageBlob->pbData,
		pSignedMessageBlob->cbData,
		TRUE)))
	{
		MyHandleError(TEXT("CryptMsgUpdate failed."));
		exit_CosignMessage(hMsg, pbCosignedMessageBlob);
	}

	// Initialize the CMSG_SIGNER_ENCODE_INFO structure for the 
	// cosigner.
	CMSG_SIGNER_ENCODE_INFO CosignerInfo;
	memset(&CosignerInfo, 0, sizeof(CMSG_SIGNER_ENCODE_INFO));
	CosignerInfo.cbSize = sizeof(CMSG_SIGNER_ENCODE_INFO);
	CosignerInfo.pCertInfo = pCosignerCert->pCertInfo;//*a_pCertContext->pCertInfo;
	CosignerInfo.hCryptProv = hCryptProv;
	CosignerInfo.dwKeySpec = dwKeySpec;
	CosignerInfo.HashAlgorithm.pszObjId = m_HashAlgorithm;//szOID_RSA_SHA1RSA;



	// Add the cosigner to the message.
	if(CryptMsgControl(
		hMsg,
		0,
		CMSG_CTRL_ADD_SIGNER,
		&CosignerInfo))
	{
		_tprintf(TEXT("CMSG_CTRL_ADD_SIGNER succeeded. \n"));
	}
	else
	{
		MyHandleError(TEXT("CMSG_CTRL_ADD_SIGNER failed."));
		exit_CosignMessage(hMsg, pbCosignedMessageBlob);
	}

	// Add the cosigner's certificate to the message.
	CERT_BLOB CosignCertBlob;
	CosignCertBlob.cbData = pCosignerCert->cbCertEncoded;
	CosignCertBlob.pbData = pCosignerCert->pbCertEncoded;

	if(CryptMsgControl(
		hMsg,
		0,
		CMSG_CTRL_ADD_CERT,
		&CosignCertBlob))
	{
		_tprintf(TEXT("CMSG_CTRL_ADD_CERT succeeded. \n"));
	}
	else
	{
		MyHandleError(TEXT("CMSG_CTRL_ADD_CERT failed."));
		exit_CosignMessage(hMsg, pbCosignedMessageBlob);
	}

	// Get the size of the cosigned BLOB.
	if(CryptMsgGetParam(
		hMsg,
		CMSG_ENCODED_MESSAGE,
		0,
		NULL,
		&cbCosignedMessageBlob))
	{
		_tprintf(TEXT("The size for the encoded BLOB is %d.\n"), 
			cbCosignedMessageBlob);
	}
	else
	{
		MyHandleError(TEXT("Sizing of cbSignerInfo failed."));
		exit_CosignMessage(hMsg, pbCosignedMessageBlob);
	}

	// Allocate memory for the cosigned BLOB.
	if(!(pbCosignedMessageBlob = 
		(BYTE*)malloc(cbCosignedMessageBlob)))
	{
		MyHandleError(
			TEXT("Memory allocation error while cosigning."));
		exit_CosignMessage(hMsg, pbCosignedMessageBlob);
	}

	// Get the cosigned message BLOB.
	if(CryptMsgGetParam(
		hMsg,
		CMSG_ENCODED_MESSAGE,
		0,
		pbCosignedMessageBlob,
		&cbCosignedMessageBlob))
	{
		_tprintf(TEXT("The message was cosigned successfully. \n"));

		// pbSignedMessageBlob now contains the signed BLOB.
		fReturn = true;
	}
	else
	{
		MyHandleError(TEXT("Sizing of cbSignerInfo failed."));
		exit_CosignMessage(hMsg, pbCosignedMessageBlob);
	}

	if(pbCosignedMessageBlob)
	{
		pCosignedMessageBlob->cbData = cbCosignedMessageBlob;
		pCosignedMessageBlob->pbData = pbCosignedMessageBlob;
	}

	return fReturn;
}

bool exit_CosignMessage(HCRYPTMSG hMsg, BYTE  *pbCosignedMessageBlob = NULL,  bool fReturn=false)
{
	// Only free the signed message if a failure ocurred.
	if(!fReturn)
	{	
		if(hMsg)
		{
			CryptMsgClose(hMsg);
		}
		if(pbCosignedMessageBlob)
		{
			free(pbCosignedMessageBlob);
			pbCosignedMessageBlob = NULL;
		}
	}
	return 	fReturn;
}

CryptMsgUpdate(hMsg, pSignedMessageBlob->pbData, pSignedMessageBlob->cbData, TRUE)
for(LONG i = 0; i < lSigners; i++)
{
     if(!(CryptVerifyMessageSignature(&VerifyParams, i,  pCosignedMessageBlob->pbData,pCosignedMessageBlob->cbData...)
     if (i == нужное значение)
        {
            if(CryptMsgControl(hMsg,0, CMSG_CTRL_DEL_SIGNER,&i))     
               //получаю подписаное сообщение с помощью двойного вызова ф-и
            if(CryptMsgGetParam(hMsg, CMSG_ENCODED_MESSAGE....)
            
           //выхожу из цикла
         }
}
 CryptMsgClose(hMsg);
......

//при проверке lSigners = 0
LONG lSigners = CryptGetMessageSignerCount(	MY_ENCODING_TYPE, pCosignedMessageBlob->pbData, 	pCosignedMessageBlob->cbData);