const TsaMaxResponseBytes= 4* 1024* 1024;
function WinHttpAvailable: Boolean;
function PostTimeStampQuery(const TsaUrl: string; const ReqDer: TBytes;
out RespDer: TBytes): Boolean;
FPdfTsaWin is the Windows-specific timestamp transport consumed by FPdfTsa. It uses the WinHttp API to POST an encoded TimeStampReq to a timestamp authority URL and collect the TimeStampResp bytes
WinHttpAvailable reports whether the WinHttp bindings resolve on this machine; PostTimeStampQuery performs the actual HTTP exchange and returns False (rather than raising) when the request fails at the transport level, letting the caller apply its own retry policy
All WinHttp handle and function-pointer bindings live in the implementation section; the interface exposes only the availability check and the post helper
| Function | Description |
|---|---|
WinHttpAvailable | Returns True when the WinHttp transport bindings can be resolved at runtime |
PostTimeStampQuery | POSTs a TimeStampReq to a TSA URL and returns the response DER; returns False on transport failure |
| Constant | Purpose |
|---|---|
TsaMaxResponseBytes | Upper bound on a timestamp response, 4 MB; a reply that exceeds it is abandoned rather than accumulated, so a hostile or broken authority cannot exhaust memory. The transports on other platforms enforce the same limit |
Content-Type: application/timestamp-query and expects application/timestamp-replyPadesTsaAvailable = False unless another transport is registered via PadesTimestampOverride