CryptDecryptMessage

function CryptDecryptMessage(

  pDecryptPara: PCRYPT_DECRYPT_MESSAGE_PARA;

  pbEncryptedBlob: LPBYTE;

  cbEncryptedBlob: DWORD;

  pbDecrypted: LPBYTE;

  pcbDecrypted: LPDWORD;

  ppXchgCert: PPCCERT_CONTEXT

):BOOL;