Validating checksum when restoring from BIP39 seed

[kacperzuk]

Currently when "BIP39 seed" option is selected in seed dialog, any seed will be accepted and "Seed type:" info will be hidden.

I would like to change the messages shown to user:

• leave them as they're now when "BIP39 seed" is not selected (so "Seed type: old/standard/2fa")
• show "Seed type: BIP39 (set in options)" when BIP39 checksum is valid and BIP39 was selected in options
• show "Seed type: BIP39 (set in options; unknown wordlist!)" when there are words outside of bundled wordlist and BIP39 was selected in options
• show "Seed type: BIP39 (set in options; invalid checksum!)" when words are from wordlist, but BIP39 checksum is invalid and BIP39 was selected in options

I understand problems with BIP39 (no versioning, checksum based on numbers from worldlist, multiple wordlists for different languages), but UX really suffer if Electrum doesn't warn about invalid checksum. I almost got heart attack when I kept entering seed with a typo and Electrum didn't say anything to me :).

However it will require bundling BIP39 wordlist with Electrum for as long as restoring from BIP39 will be supported and as I understand we can't rely that current wordlist used by Electrum will always be the same as BIP39.

So my question is: would you merge a PR that implements this or is the wordlist issue a deal breaker (I'll totally understand that)?

[ecdsa]

We already use the English wordlist, so it's possible to checksum of English seeds without wordlist additions; I did not do it because I lacked time. I would merge it, but I do not guarantee that BIP39 will forever be supported in Electrum; it will be messy if they extend it to derive segwit addresses.

[westonal]

I almost got heart attack when I kept entering seed with a typo and Electrum didn't say anything to me

👍

At least let us know somehow if the words typed are not on the English word list.

I do not guarantee that BIP39 will forever be supported in Electrum

But you support it now, why can't the support be better? And why does that imply supporting it forever?

[dabura667]

why can't the support be better?

Supporting one checksum check (English only) is unfair. Every wordlist in the future will come up and say "well, you did it for English! Do it for us!" And then eventually, Thomas is stuck making sure checksum checks work for all the wordlists.

Electrum's BIP39 full support was never guaranteed.

[westonal]

@dabura667 does #2727 actually cover this? and for all languages.

[dabura667]

@westonal not in its current state. Though the author seems to understand what to do.

A checkbox off by default is fine, that way if it breaks, we can just ping the author of the PR and wait for him to fix it if ever.