Digital Signing

Choose a PDF or drag it onto the area. The server writes an identifier into its metadata, signs the file with mahevi’s certificate (SHA-256) and downloads it straight away under its own name. It is this downloaded file that gets passed on, not the original.

Choose a PDF that was signed here, or drag it onto the area. The server reads the identifier from its metadata, fetches the signature stored for it and checks it against every byte of the file. The result appears below the area.

“Valid”: the file is, byte for byte, the one that was signed. “Not valid”: it has been changed since – saving it again, filling it in or printing it to PDF is enough – or it was not signed here. The check does not say which of the two it is. “Check not possible”, on the other hand, means the server could not check just now: it says nothing about the file.

Both run on mahevi’s server, not in the browser – that is where the private key is kept. The signature is not inside the PDF itself: a PDF reader does not show it, and it can only be checked here. It is not a qualified electronic signature.

Signing keeps a copy of the signed PDF and its signature on the server – otherwise there would be nothing to check against later. A PDF that is only checked is not stored. Signing is limited to a fixed number of documents a day, for everyone together. Once that is reached, it works again the next day.