tarsnap

Online encrypted backup service (client)

Tarsnap is an online encrypted backup service. It presents a tar-like command-line interface, but stores data online rather than locally; using ideas taken from the author's FreeBSD Update and Portsnap utilities, it maximizes performance by recognizing duplicate data and only storing it once, and cryptographically encrypts and signs archives using locally-held keys in order to guarantee that nobody without access to the key file (including the author) can read or modify archives.