"Number of words" dropdown should only allow multiples of 3 about bip39 HOT 4 CLOSED

This is a good idea.

I can envisage a few different approaches:

• Use a select tag. However, this reduces flexibility. If someone wants a 48 or 300 word mnemonic, the number of options will have to be massive.
• Add a step="3" attribute on the input so it only changes by multiples of 3. This doesn't assist with communicating the need for multiples of three, but it does allow for much more flexible mnemonic sizes.
• Add help-text to the form, linking to the reason for multiples of three.

I prefer the step attribute with help-text; let me know your thoughts.

from bip39.

I think help-text is a good idea, but the bip32 spec is pretty unfriendly, so I would pare it down to the essentials. Either put it in a tooltip/mouseover, and/or if there is an faq put it in the faq and link to the full spec from the faq.

pared down explanation:

"Q: Why are bip32 pass phrases always a multiple of 3 words long?
A: bip32 entropy seeds are sequences of 32 bits of entropy and 1 bit of checksum, for a total of 33 bits for each chunk of the sequence. So seed is always 33*x bits total. Each passphrase word codes 11 bits, so pass phrases are 3 * x words long, for 3 * 11 * x bits total. BIP32 SPEC link. PS: Use 12 words for safety. 6 might be safe for small amounts of bitcoin, and 3 is definitely not safe!" with a link at the end there. "

from bip39.

No one is going to want more than 24 words mnemonic, that's just silly

https://en.wikipedia.org/wiki/Password_strength#Required_Bits_of_Entropy

Have options for 6, 12, 18, and 24 words. Good enough.

(12 words should be default imho.)

Select tag is fine, I guess either is fine really. (I didn't understand step = 3 plan tbh.)

from bip39.

Good point about required entropy.

I've kept the default strength as 15 based on #11

Thanks for your input!

from bip39.