Put it in a text document, zip it with encryption, print out the binary data, send it via morse code, type it into a raw file and saved as a zip, then repeat the same procedure (with a new password) to get the password to the zip file. now you have two zip files, and the second zip file has, in it, the password to the first zip file. Keep doing this for all eternity, until the universe contracts to a single point. Continue until arriving at the first password you entered. Now, reverse time and, with the password in possession, travel backward through the beginning of time, through to the end of the previous universe, all the way back to when the first password was sent to you. The password you have in hand should open the file.
I have commenced construction of a box that will do this, but it might take me five or six universal cycles to completely debug.
Now, the complexities of time travel aside, why wouldn’t this procedure work?