Light Wallet: Run client in browser WASM PoC

[jpraynaud]

Why

We want to make Lace (which runs in the browser) "Mithril aware", which means that it needs to be able to verify Mithril certificates.
This feature will provide support for light wallet integration with Mithril: retrieve the Utxos of a limited set of addresses with a cryptographic proof.

What

We need to explore the usage of the Mithril client in the browser, which is the first mandatory step toward integration with Lace.
Our first objective is to verify a Mithril certificate in the browser. We want to know if this is possible, and we also want to get a better understanding of what it requires on our end (new developments, how to deliver software, ...)

How

• Compile a "light" binary in WASM that embeds the STM library and verifies a multi-signature (can be hard-coded)
• Compile a "light" binary in WASM that embeds the Ed25519-Dalek library and verifies a genesis signature (can be hard-coded)
• Compile a "light" binary in WASM that downloads and verifies the whole certificate chain
• Compile the client in WASM

[jpraynaud]

• The PoC has been pushed on the branch ensemble/1254-poc-wasm-client.

• The README file to run the PoC is available here:
  https://github.com/input-output-hk/mithril/blob/ensemble/1254-poc-wasm-client/poc_wasm_client/README.md

• The PoC is plugged in the certificate modal popup of the explorer:
  

• Which links to the page to verify the certificate:
  

[jpraynaud]

Hi @curiecrypt and @iquerejeta, we have modified the STM library in order to make it compile in WASM as explained in this commit: 858f016

The aggregate_verify BLST function was not found by the compiler, and we received this error:

Build error with BLST:
error[E0599]: no method named  found for struct  in the current scope

Do you have any idea of what could be the problem?