perkeep/doc/schema/objects/permanode.txt

The idea of a permanode is that it's the anchor from which you build
mutable objects.  To serve as a reliable (consistently nameable)
object it must have no mutable state itself.

{"camliVersion": 1,
 "camliType": "permanode",

 // Required.  Any random string, to force the sha1 of this
 // node to be unique.  Note that the date in the ASCII-armored
 // GPG JSON signature will already help it be unique, so this
 // doesn't need to be a great random.
 "random": "615e05c68c8411df81a2001b639d041f"

<REQUIRED-JSON-SIGNATURE>}