Encoding for Robust Immutable Storage (ERIS) and Guile

[pukkamustard <pukkamustard@posteo.net>]

Hello Guile Users,

I'm happy to announce guile-eris 0.2.0. This is a Guile 
implementation
of "Encoding for Robust Immutable Storage (ERIS)" [1].

ERIS defines how an arbirtary sequence of bytes can be encoded 
into a set
of uniformly sized blocks and an identifier (read capability). The
blocks are encrypted such that the original content can only be 
decoded
given the read capability. ERIS is a scheme for content-addressing 
in
the sense that the read capability is deterministically computed 
from
the content itself.

This is done by splitting content into blocks, encrypting them and
collecting references to blocks in a higher-level node (i.e. 
building a
Merkle Tree). See the specification [1] for a detailed description 
of
the encoding.

Encodings like ERIS are common in protocols such as Bittorrent, 
GNUNet,
IPFS, et. al. ERIS decouples the encoding from any particular 
protocol
or application, allowing content to be referenced regardless of 
storage
and transport layer. For example ERIS encoded content can be 
stored and
transported over IPFS [2], but also over HTTP or via an USB stick.

My interest in developing this has been for an ActivityPub-esque
applications where content can be cached and replicated to make
availability of content more robust. There seem to be many other
applications, including Guix substitutes.

ERIS is still "experimental". This release is intended to initiate
discussion and collect feedback from a wider circle. In particular 
I'd
be interested in your thoughts on applications and the Guile API.

ERIS is very much related to Datashards [3] and is in progress of
converging closer.

I have submitted a patch to Guix. You should be able to start
experimenting with ERIS with `guix environment --ad-hoc guile-eris
guile` shortly.

Thanks and happy hacking!
-pukkamustard

[1] http://purl.org/eris
[2] 
https://gitlab.com/openengiadina/eris/-/blob/main/examples/ipfs.org
[3] https://datashards.net/