tzstamp-client is the command line client for the TzStamp server software. It lets users stamp and verify files. A full description of its functionality can be found in its manual page.
Assuming a fresh install you'll need to
apt-get some dependencies:
sudo apt-get install git nodejs npm
Upgrade the system installation of npm:
sudo npm install --global --upgrade npm
Upgrade the system installation of node:
sudo npm install --global --upgrade node
Then install the tzstamp package with npm:
npm install -g @tzstamp/cli
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The original file you timestamped or its SHA-256 hash.
The proof JSON file returned by the tzstamp server.
With these run the
tzstamp verify a.png 1ab1b7db1f4a533de4294166cd3df01403b11c84c16f178a4807b94aa858c3fb.json
If your 'file' is actually a set of bytes, say a block of text, you can also pass the sha256 directly in place of a filename.
tzstamp verify a4e9de2410c9e7c3ac4c57bbc18beedc5935d5c8118e345a72baee00a9820b67 1ab1b7db1f4a533de4294166cd3df01403b11c84c16f178a4807b94aa858c3fb.json
You should get back a derived Tezos block and timestamp:
Verified Target: /home/user/Downloads/Streisand_Estate_800_521.jpg Hash existed at 6/1/2021, 6:30:54 AM Block hash: BLQFwmjYJDTyT6wjEwKyot2RFC8wZf9Qyzo56fQ5x4nUYjnfKid Node queried: https://testnet-tezos.giganode.io/
If the proof is high stakes you should also manually check this block hash against the published blocks on mainnet. The block should exist at some point in time, if you can't find it the proof may be invalid.
Timestamping a file
Files or their hashes can be timestamped like so:
tzstamp stamp filename.txt tzstamp stamp 4a5be57589b4ddc42d87e4df775161e5bbcdf772058093d524b04dd88533a50a