When hostage takers wish to prove that they're releasing recent footage, they'll use a newspaper — these are produced by an external authority and publicly verifiable. This service offers a newspaper-like service for files, with the added usefulness of being able to prove the age (as well as youth) of said files.
When you submit a file, we take many different and common hashes, storing them along with the server time in a record that we keep private. This is, in effect, a photo of your file next to our clock. Entering any of the hashes we have taken, or the original file, will tell you when it was first (and last) seen, thus proving its age.
Essentially, we rely on the crytographic nature of many hash functions (or the cryptographic nature of cryptography) to ensure that, if your file verifies on here, it has not changed since it was first submitted. This can be useful if you're emailing someone a file and need to prove it was in for a deadline, etc.
Use the forms below to submit or test files. When you first submit a file, you'll get a listing of all the hashes we take, and a removal code. This code can be used, along with any of the hashes or the original file, to remove a file from our servers. Note that we do not store your file, only hashes thereof, and we do not store, reuse, or log your email address.
There is also a web service available (here), and documentation for that can be found here Files submitted using the web service are visible using the web interface and vice versa.
A working ruby library and command-line utility is available that interacts with the web service. It's available at timeverify.tgz. You'll need the rest-client gem, but other than that it has no dependencies beyond standard ruby 1.9.
Submit a file below to register it with the service. It will forward you to a receipt page and, optionally, email you a copy of the file info. Max filesize is currently 10 MiB
Verifying a file will tell you when it was first seen (and when the service last registered it). To verify a file, compute its hash and copy it into the box below.
You can also upload a file to be checked.
If you have a listing to remove, simply enter its removal key below.
Alternatively, you can supply the file and removal key. Max filesize is currently 10 MiB.
Submit a file below to have it signed using PGP. This will output a digital signature that can be checked for authenticity by importing the public key below. Note that using this method means we do not even store the fact that we have seen your file, making it ideal for the paranoid. Max filesize is currently 10 MiB
The public key for this service is available for download from the service itself.