I am trying to use the jwt_simple library in a cloudflare workers webassembly runtime. Following the basic example in the linked documentation, everything works fine up until key.authenticate(claims)? is executed, at which point the following stack trace is generated in my terminal running wrangler:
ReferenceError: performance is not defined
at __wbg_now_63f780680ee9cc56 (./index_bg.mjs:331:15)
at wasm://wasm/001926f2:wasm-function[264]:0x252a9
at wasm://wasm/001926f2:wasm-function[409]:0x2925d
at wasm://wasm/001926f2:wasm-function[167]:0x1fb99
at wasm://wasm/001926f2:wasm-function[410]:0x292b9
at wasm://wasm/001926f2:wasm-function[284]:0x25ea0
at wasm://wasm/001926f2:wasm-function[132]:0x1cbd9
at wasm://wasm/001926f2:wasm-function[38]:0x9bbc
at wasm://wasm/001926f2:wasm-function[143]:0x1dc3b
at wasm://wasm/001926f2:wasm-function[106]:0x19ccb at line 330, col 13
I suspect this is because when key.authenticate is trying to verify the jwt is still valid it calls performance.now, which as per this forum post is not provided by cloudflare workers to prevent timing attacks. I don't fully understand how webassembly works, but I do know that I can polyfill performance.now in javascript as is done here.
How could I use this polyfill in a webassembly environment?
Replace all instances of performace.now() after the file builds:
$ sed -i '' 's/performance.now()/Date.now()/' index_bg.mjs