да, вот что такое PCRYPT_DECRYPT_MESSAGE_PARA?

// Объявление и инициализация локальных переменных.
DWORD cbDecryptedMessage;
char* EncryptedString = new char[(cbEncryptedBlob * 2) +1];
HCERTSTORE CertStoreArray[] = {hStoreHandle};
CRYPT_DECRYPT_MESSAGE_PARA DecryptParams;
DWORD DecryptParamsSize = sizeof(DecryptParams);
BYTE* pbDecryptedMessage;
LPSTR DecryptedString;
BOOL fReturn = TRUE;

//+-------------------------------------------------------------------------
// The CRYPT_DECRYPT_MESSAGE_PARA are used for decrypting messages.
//
// The CertContext to use for decrypting a message is obtained from one
// of the specified cert stores. An encrypted message can have one or
// more recipients. The recipients are identified by their CertId (Issuer
// and SerialNumber). The cert stores are searched to find the CertContext
// corresponding to the CertId.
//
// Only CertContexts in the store with either
// the CERT_KEY_PROV_HANDLE_PROP_ID or CERT_KEY_PROV_INFO_PROP_ID set
// can be used. Either property specifies the private exchange key to use.
//
// cbSize must be set to the sizeof(CRYPT_DECRYPT_MESSAGE_PARA) or else
// LastError will be updated with E_INVALIDARG.
//--------------------------------------------------------------------------
type
PCRYPT_DECRYPT_MESSAGE_PARA = ^CRYPT_DECRYPT_MESSAGE_PARA;
CRYPT_DECRYPT_MESSAGE_PARA = record
cbSize :DWORD;
dwMsgAndCertEncodingType :DWORD;
cCertStore :DWORD;
rghCertStore :PHCERTSTORE;
end;