Crypto unavailable in React Native (non-node, non-browser) runtimes

[bradjones1]

The change in #2762 is great, but it underscores an important limitation: The SDK cannot provide E2E encryption support in a runtime that lacks a WebCrypto implementation, e.g. React Native.

This SDK is amazing and I totally appreciate all the hard work that goes into it by the Matrix team. I did, however, need to do a bit of creative work to shim in at least some sort of crypto module to get my RN project building, due to the new src/crypto/crypto.ts being evaluated at build-time.

I wonder if it's possible to somehow tighten this up to bail out of loading any Crypto functionality if it's unsupported by the runtime?

[t3chguy]

need to do a bit of creative work to shim in at least some sort of crypto module to get my RN project building

How is it failing otherwise?

Is it just the require failing? We should wrap it in a try-catch
Should also add setter for the crypto, subtleCrypto & TextEncoder variables to allow easier shimming

[bradjones1]

The related PR is a good step to address

add setter for the crypto, subtleCrypto & TextEncoder variables to allow easier shimming

however to your question:

Is it just the require failing?

I think so. I ended up shimming this to get my app building but I will report back here when I do remove the shim and see if these changes fixed this in my particular case.