(finally) write a front page README, add a PDF with 16 factsheets abo…

…ut tinySSB

README.md

@@ -4,6 +4,76 @@
 
 ## Overview
 
-lore ipsum
+tinySSB is a variation of Secure Scuttlebutt (SSB)
+[https://scuttlebutt.nz/](https://scuttlebutt.nz/), a radically
+decentral approach of implementing distributed applications. In a
+nutshell, with SSB we get "social media without servers".
+
+## How it works
+
+The core of SSB are single-author append-only logs that are replicated
+at will and on a best-effort basis. Eventually, all updates to a log
+will reach the interested parties who can verify the authenticity and
+integrity of each update.  This also applies to auxiliary forwarders,
+making any SSB-aware entity a potential link in the forwarding chains.
+Any means of replication is fine, which can be BlueTooth Low Energy,
+Internet protocols, USB sticks, or data printed on paper, collected
+and dispatched centrally or simply using a gossip protocol: anything
+goes!
+
+Each append-only log is a trivial _Conflict-free Replicated Data Type_
+(CRDT). A set of append-only logs also of a CRDT. CRDTs are best
+understood as virtual (because distributed) data where a local site
+keeps a copy and can act on this copy. CRDTs are designed such that
+any local modification results in update messages sent to the other
+replicas: if these updates are ingested correctly, all replicas will
+converge to the same shared state, without any central entity having
+to intervene or help. Writing distributed applications as and with
+CRDTs requires careful design but has a huge reward in unbounded
+scallability, in applications that continue to work when the device is
+offline because all updates seamlessly merge into the other replicas
+when the device reconnects. Go decentral!
+
+
+## The difference between SSB and tinySSB
+
+tinySSB inherits the core concepts of "classic" SSB i.e., the
+append-only logs with signed entries, the encryption suite etc.  The
+novelty of tinySSB lies in its
+
+- binary packet format (instead of JSON)
+- “shadow packet headers” that avoid sending and storing redundant data
+- the absence of “blobs” outside the append-only logs, using side chains instead
+
+The data packet format has been made extremely small, namely 120
+Bytes.  The point is to enable the use of tinySSB in challenged
+environments where bandwidth and storage resources are scarce.
+
+tinySSB runs over Bluetooth Low Energy (BLE), over long-range radio
+(LoRA), and perhaps in the future even over shortwave in the amateur
+radio bands, bouncing off the ionosphere. Embedded devices are
+powerful enough to handle these packets and serve well as cheap
+forwarders.
+
+At the higher level, the design of distributed applications over
+tinySSB as well as SSB is identical - it's a CRDT world.
+
+tinySSB is used for teaching distributed programming concepts and
+skills at the Computer Science Bachelor and Masters level at the
+University of Basel.
+
+
+## tinySSB Tech Gallery
+
+(see the respective folders)
+
+- Android
+- ESP32
+
+
+
+## Documentation
+
+-- 16 factsheets made for the [dWeb camp 2024](https://dwebcamp.org/), Aug 2024: [PDF](doc/tinySSB-factsheets-v2b.pdf)
 
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