if not CryptAcquireContext(@Prov, PChar('PlatTest'), PChar('Crypto-Pro GOST R 34.10-2001 Cryptographic Service Provider'), 75, 0) then  // 4289709 PChar('4DF6 72DA 0002 0001 AEBB')
    ShowMessage(SysErrorMessage(GetLastError));
  if not CryptCreateHash(Prov, CALG_MD5, 0, 0, @Hash) then
    ShowMessage(SysErrorMessage(GetLastError));
  Buf := BytesOf(ECP);
  iSize := SizeOf(Buf);
  if not CryptHashData(Hash, @Buf, iSize, 0)then
    ShowMessage(SysErrorMessage(GetLastError));
  BufLen := 0;
  if not CryptSignHash(Hash, AT_SIGNATURE, nil, 0, nil, @BufLen) then
    ShowMessage(SysErrorMessage(GetLastError)); // Вот тут он пишет, что неверный алгоритм выбран...
  if BufLen > 0 then
  begin
    GetMem(sign, BufLen);
    if not CryptSignHash(Hash, AT_SIGNATURE, nil, 0, sign, @BufLen) then
      ShowMessage(SysErrorMessage(GetLastError));
    Stream := TMemoryStream.Create;
    Stream.Position := 0;
    Stream.Write(Sign, buflen);
    SignData := Stream.ToString;
  end;