Chatting with one of Google’s Trillian team, I was encouraged to explore Trillian’s Map Mode. The following is the result of some spelunking through this unfamiliar cave. I can’t provide any guarantee that this usage is correct or sufficient.

Here’s the repo: https://github.com/DazWilkin/go-trillian-map

I’ve written about Trillian Log Mode elsewhere.

I uncovered use of Trillian Map Mode through Trillian’s integration tests. I’m unclear on the distinction between TrillianMapClient and TrillianMapWriteClient but the latter served most of my needs.

I’ve been playing around with a proof-of-concept combining WASM and Trillian. The hypothesis was to explore using WASM as a form of chaincode with Trillian. The project works but it’s far from being a chaincode-like solution.

Let’s start with a couple of (trivial) examples and then I’ll explain what’s going on and how it’s implemented.

2020/08/14 18:42:17 [main:loop:dynamic-invoke] Method: mul
2020/08/14 18:42:17 [random:New] Message
2020/08/14 18:42:17 [random:New] Float32
2020/08/14 18:42:17 [random:New] Float32
2020/08/14 18:42:17 [random:New] Message
2020/08/14 18:42:17 [random:New] Float32
2020/08/14 18:42:17 [random:New] Float32
2020/08/14 18:42:17 [Client:Invoke] Metadata: complex.wasm
2020/08/14 18:42:17 [main:loop:dynamic-invoke] Success: result:{real:0.036980484 imag:0.3898267}

After shipping a Rust-sourced WASM solution (complex.wasm) to the WASM transparency server, the client invokes a method mul that’s exposed by it using a dynamically generated request message and outputs the response. Woo hoo! Yes, an expensive way to multiple complex numbers.

I’ve been hacking on a Rust-based transparent application for Google Trillian. As appears to be my fixation, this personality is for another package manager. This time, Rust’s Crates often found in crates.io which is Rust’s Package Registry. I discussed this project earlier this month Rust Crate Transparency && Rust SDK for Google Trillian and and earlier approach for Python’s packages with pypi-transparency.

This time, of course, I’m using Rust. And, by way of a first for me, for the gRPC server implementation (aka “personality”). I’ve been lazy thanks to the excellent gRPCurl and have been using it way of a client. Because I’m more familiar with Golang and because I’ve written (most) other Trillian personalities in Golang, I resorted to quickly implementing Crate Transparency in Golang too in order to uncover bugs with the Rust implementation. I’ll write a follow-up post on the complexity I seem to struggle with when using protobufs and gRPC [in Golang].

I’m noodling the utility of a Transparency solution for Rust Crates. When developers push crates to Cargo, a bunch of metadata is associated with the crate. E.g. protobuf. As with Golang Modules, Python packages on PyPi etc., there appears to be utility in making tamperproof recordings of these publications. Then, other developers may confirm that a crate pulled from cates.io is highly unlikely to have been changed.

On Linux, Cargo stores downloaded crates under ${HOME}/.crates/registry. In the case of the latest version (2.12.0) of protobuf, on my machine, I have:

I’ve written previously (Google Trillian for Noobs) about Google’s interesting project Trillian and about some of the “personalities” (e.g. PyPi Transparency) that I’ve build using it.

Having gone slight cra-cra on Cloud Run and gRPC this week with Golang gRPC Cloud Run and gRPC, Cloud Run & Endpoints, I thought it’d be fun to deploy Trillian and a personality to Cloud Run.

It mostly (!) works :-)

At the end of the post, I’ve summarized creating a Cloud SQL instance to host the Trillian data(base).

I’ve finally being able to hack my way through to a working Rust gRPC client (for PyPi Transparency).

It’s not very good: poorly structured, hacky etc. but it serves the purpose of giving me a foothold into Rust development so that I can evolve it as I learn the language and its practices.

There are several Rust crates (SDK) for gRPC. There’s no sanctioned SDK for Rust on grpc.io.

I chose stepancheg’s grpc-rust because it’s a pure Rust implementation (not built atop the C implementation).

I’ve been noodling around with another Trillian personality.

Another in a theme that interests me in providing tamperproof logs for the packages in the popular package management registries.

The Golang team recently announced Go Module Mirror which is built atop Trillian. It seems to me that all the package registries (Go Modules, npm, Maven, NuGet etc.) would benefit from tamperproof logs hosted by a trusted 3rd-party.

As you may have guessed, PyPi Transparency is a log for PyPi packages. PyPi is comprehensive, definitive and trusted but, as with Go Module Mirror, it doesn’t hurt to provide a backup of some of its data. In the case of this solution, Trillian hosts a log of self-calculated SHA-256 hashes for Python packages that are added to it.

The goal of pypi-transparency is very similar to the underlying motivation for the Golang team’s Checksum Database (also built with Trillian).

Even though, PyPi provides hashes of the content of packages it hosts, the developer must trust that PyPi’s data is consistent. One ambition with pypi-transparency is to provide a companion, tamperproof log of PyPi package files in order to provide a double-check of these hashes.

It is important to understand what this does (and does not) provide. There’s no validation of a package’s content. The only calculation is that, on first observation, a SHA-256 hash is computed of the package’s content and the hash is recorded. If the package is subsequently altered, it’s very probable that the hash will change and this provides a signal to the user that the package’s contents has changed. Because pypi-transparency uses a tamperproof log, it’s very difficult to update the hash recorded in the tamperproof log, to reflect this change. Corrolary: pypi-transparency will record the hashes of packages that include malicious code.