Update README

README.md

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 # ArmoredWitness
 
-ArmoredWitness is an implementation of a witness for transparency logs.
+The ArmoredWitness project is intended to kick-start a cross-ecosystem witness network, providing split-view attack prevention to a growing set of transparency-enabled ecosystems.
 
-This repo will contain tooling and documentation for the project.
+## Background
 
-## Related Repos
-* [Trusted Applet](https://github.com/transparency-dev/armored-witness-applet)
-* [Trusted OS](https://github.com/transparency-dev/armored-witness-os)
-* [Bootloader](https://github.com/transparency-dev/armored-witness-boot)
-* [Recovery Image](https://github.com/usbarmory/armory-ums)
+Transparency systems work by ensuring that all actors in a given ecosystem see the same append-only list of data, typically stored in [verifiable logs](https://transparency.dev/verifiable-data-structures/). This allows folks relying on this data to be confident that even if they are unable to determine the correctness of the data themselves, it is visible to others who _can_ verify it and call out badness.
+
+If a malicious log is able to present inconsistent views of itself to different roles, then such badness will go undetected.
+
+Witnessing is a solution to this "split-view" attack - well-known identities verify the append-only property of the logs; countersigning checkpoints (commitments to the state of a log) which have been proved to be consistent with all earlier checkpoints from the same log which have also been seen by the witness.
+
+## Goals
+
+We want to:
+
+* **Help transparency-enabled ecosystems further tighten their security properties.** \
+By providing a lightweight network which is compatible with ecosystems using a [common checkpoint format](https://github.com/transparency-dev/formats/tree/main/log), we can help reduce the trust being placed in log operators.  \
+Existing compatible ecosystems include: Go's sum DB, Sigstore, Pixel Binary Transparency, LVFS, SigSum, ArmoryDrive.
+* **Ensure the ArmoredWitness device is as low-touch and maintenance-free as possible.** \
+We don't want to ask anyone to be a full-time system administrator for these devices, they should be as "plug-in and go" as possible.
+* **Bootstrap a diverse witnessing ecosystem** \
+Encourage others to participate, learn with us, and potentially even go on to develop their own witness protocols and networks, ideally in such a way that interoperability remains possible and enables greater diversification of reputational trust.
+
+## Device
+
+The ArmoredWitness device is a small networked device based on the [USBArmory](https://inversepath.com/usbarmory) that runs an open-source implementation of a witness configured to support a growing number of transparency-enabled ecosystems.
+
+![alt_text](images/armored-witness-render.png "ArmoredWitness case render")
+
+We're making a small number of these devices, and plan to distribute them to folks who are passionate about one or more of the witnessed ecosystems.
+
+The ArmoredWitness devices will only run the ArmoredWitness firmware, so will not be repurposable for other use cases.
+
+TODO: We'll add more information about the hardware
+
+## Software
+
+The firmware for the ArmoredWitness is all written in Go, and compiled with [TamaGo](https://github.com/usbarmory/tamago) into a bare-metal executable. This enables us to take advantage of Go's memory safety and excellent standard library, and avoid needing to take a dependency on any traditional generic bootloader/kernel/OS combinations, considerably reducing the surface area of the codebase.
+
+There are 3 main parts to the ArmoredWitness firmware stack:
+
+* Bootloader \
+<https://github.com/transparency-dev/armored-witness-bootloader> \
+A very simple TamaGo unikernel which loads the OS from MMC, verifies it, and finally boots it.
+* Trusted OS \
+<https://github.com/transparency-dev/armored-witness-os> \
+The OS is a TamaGo unikernel which is primarily concerned with:
+  * Managing the device hardware (Ethernet, storage, LEDs, etc.),
+  * Loading and verifying the Applet from MMC, and executing it inside a TEE,
+  * Providing an RPC-like syscall interface to the Applet.
+* Witness Applet \
+<https://github.com/transparency-dev/armored-witness-applet>  \
+The Trusted Applet is where the witness itself lives. \
+In addition to running the witness code, the applet also handles the TCP/IP side of networking (using RPC to send/receive packets).
+
+Along with other ancillary parts:
+
+* Tooling \
+This repo contains some tooling to help provision the factory-fresh devices into ArmoredWitness devices.
+* Recovery Image \
+<https://github.com/usbarmory/armory-ums>