Oh, `b64.asciiToBinary` tripped me off, I thought it was about base64, but it encodes any string using utf-8, which is fine for what you use it but a bit confus

Oh, `b64.asciiToBinary` tripped me off, I thought it was about base64, but it encodes any string using utf-8, which is fine for what you use it but a bit confusing to the reader. About TextDecoder/TextEncoder not being the reverse of one another, I suspect you are not feeding it text but random bytes, which can cause that behaviour.