Interesting angle on idea of file security

hamster

Anyone know of a program that allows you to do this:


1. You send a zipped file to a friend but you password protect it first (a bit like winrar or winzip).

2. The password is generated based on a changing variable, eg a future date.

3. You give your friend the password for that date. ie it won't work before/after that date.

4. But you yourself can open it on any date by generating another password using step 2. Basically a keygen.

Is there any existing tool that anyone knows about like this either on Windows or Linux? Or maybe any of the existing array of zip or encryption tools under Linux?

James.

dmd

Can I ask one thing, what exactly do you want to do?
Do you want if for secure transmission? Do you want
to keep it encrypted for a backup? or do you just want it
encrypted for whatever reason?

If you want to transfer it securely but don't care about the other end,
just scp it if you can.

If you want to keep it encrypted for a backup, why not use gpg?
If you just want to keep it as a file encrypted on your local harddrive,
why not (again) use gpg?

dmd.

hamster

Hi dmd,

Actually I was just thinking of a scenario where you want someone to be able to open a file with a password you give them that would only work on a particular day. Basically like a keygen generator that you'd use say for winzip name reg tool. Except it acts as a time limited password.

phaxx

What use is a time limited access to a zip/compressed file when people can just extract it and not use the zip after that?

hamster

phaxx,

I see what you mean.... hmm.. maybe instead instead said file an executable time limited .exe ?

scojones

people can change the time/date on their pc you know....

dmd

This does depend on what you want.

Basically, you are bob, you are sending it to alice.
Now, do you want alice to be able to open this file any time?
or do you want alice to only open it once? and not be able to do
anyhting with it again?

Think of it this way, if the person can see it once, who's
to say they won't just decrypt and >> it to a file, then send
it to eve. The point is, I would consider why exactly
you want to do this, and then look at existing solutions
which work and have been well tested.

Capt'n Midnight

Pkzip (the old dos version and it's many clones) will accept the password on the console - so you are down to writing a batch file

You could write a program which looks at a time server on the internet to verify the time. This program would then display the password once the time has elapsed..

Some mail servers allow you to send an email in the future - so you have the pw queued for the future.

You could also post the PW on the internet on that day....


maybe do a search on escrow

hamster

Thanks for that Capt'n Midnight

phaxx

PGP and GNUPG both support encrypting things with a time-limited key. One can set an expiration date.

PGP also supports creating self-extracting encrypted archives, but I'm not sure if they will allow you to use a time-limited key.