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The Expire date (if entered) must be a valid UTC date format.
The format can be one of the following:
- 2016-01-29
- 2016-01-29 14:23
- 2016-01-29 14:23:50
The date can also be in a relative format to now, to specify for example 1 hour into the future:
- 1h specifies the file to expire in one hour
- 1d specifies the file to expire in one day
- 1m specifies the file to expire in one minute
The above formatters can be entered repeatedly or in combinations inside the expire date to precise the value, like:
- 1d 2h 30m will make it 1 day, 2 hours and 30 minutes into the future.
If an expire date has been set, the physical file will be deleted from the server.

Locking with a private key means to restrict access to the file by a longer key than the id-key of the file.
The format of such URL will be https://dl.nprog.com/<fileKey>/<accessKey>