It's base64, but with added checksums, yeah. There's very little that I use off-the-shelf in Tarsnap -- generally speaking I take existing standards and then m

It's base64, but with added checksums, yeah. There's very little that I use off-the-shelf in Tarsnap -- generally speaking I take existing standards and then make tweaks as needed to optimize for Tarsnap's use case. (Sometimes, as with scrypt, I decide that existing standards simply aren't any good and develop my own from the ground up.)