Send a contract that expires on a date

A draft sent to the other side is meant to be read this month and not next year. This seals it with a password and writes a deadline into the container, and says plainly what that deadline is worth.

• AES-256 encryption with a key stretched from your password.
• A deadline written into the container and checked when it is opened.
• The same format as the desktop app, so a container opens in either.

The encryption is the protection

The password is what keeps the document shut. The key is stretched from it with a hundred thousand rounds before anything is encrypted, and the content is sealed with authenticated encryption, so a container that has been altered fails to open rather than opening wrong.

The deadline is a different kind of thing and this page says so rather than implying otherwise. It is stored in the clear, outside the sealed part, and it is checked against the clock of whatever machine opens the container. It is an instruction to software, not a lock. Somebody determined to read the file after the date has ways, and the password is what actually stands between them and the contents.

What is deliberately not offered

The desktop version of this can also be set to destroy the file after the deadline. That is not offered here, because a web page cannot delete a file on the machine holding it, and naming a mode after something the tool does not do is worse than not having it.

Leaving it out removes a real hazard as well. On the desktop the deadline is checked before the password is, so a container past its date is destroyed by a typo. Nothing here destroys anything, ever: an expired container is refused and stays exactly where it is.

Pick a password worth having and send it by some other route than the one carrying the container. A deadline that software honours and a password mailed underneath the attachment are not security, and the whole point of saying all this on the page is that the feature is easy to over-trust.

What happens after the deadline?

The container refuses to open and says the deadline has passed. Nothing is deleted and the file is unchanged.

Can the recipient open it without this site?

The desktop app reads the same format. Otherwise they open it here, which also runs entirely on their own machine.

Support and billing: support@gosmartpdf.com. Operated by Mrityunjay Kumar, India. Payments by Dodo Payments, our merchant of record.

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