BIP39 works fine with entropy generated without a computer. I personally recommend using coinflips with Von Neumann skew correction.
Yes, you need to perform a SHA256 hash to calculate the checksum word. You need to use SHA512 HMAC as the next step, and EC point multiplication along with a host of other steps which are unrealistic to expect a human to perform by hand to actually get child keys and addresses out the other end, too. I have a bootable UEFI application for generating a mnemonic with skew-corrected coinflips (among other things), designed for airgapped operation, lying around in my archive somewhere. I plan on re-implementing it as part of a much larger, long-running project but if there's interest I can go find it, clean it up and publish the old version in the meantime. The spec doesn't need to change; there's really no benefit to generating a mnemonic without the SHA256 hash step, because again, you can't do anything with that mnemonic without hashing. As for encoding derivation paths in the mnemonic, Electrum's Seed Version System achieves roughly the same thing, but descriptors are a better solution for managing non-entropy metadata for wallets. For those who really don't want to put in the small amount of additional effort required to use descriptors, replying on the standard derivation paths is sufficient, as long as they're made aware of their existence. Educating your users is a better solution than attempting to abstract away (aka hide) critical information from them. On Fri, 23 May 2025 13:15:41 +0000 (UTC) Eric Kvam <[email protected]> wrote: > *Motivation* > Make it easy for users to manually create their seed phrase so that > they don't have to trust a "black box" and allow for encoding > derivation path in seed phrase to simplify recovery > > *How* > Use every eighth word from the wordlist to generate 16 word phrases > with 128 bits of entropy (no checksum). The most significant eight > bits of each word are used as entropy. The least significant three > bits of each word specify the derivation path. > > - *000* Derivation Path Not Specified > - *001* m/44'/0'/0' > - *010* m/49'/0'/0' > - *011* m/84'/0'/0' > - *100* m/48'/0'/0'/2' > - *101* m/86'/0'/0' > > Up to seven derivation paths can be specified if all words have the > same least significant bits. If the least significant bits of each > word vary, there are 48 bits that can be used to encode meta-data. > As long as meta-data is limited to certain allowable values, this > provides a mechanism for error detection, similar to a checksum. > > *Benefits of Suggested Implementation* > > - The word length determines how the seed phrase should be > interpreted. User only needs to know how many words they have and how > many words the wallet supports to check for compatibility with this > extension > - Uses same wordlist to represent the same entropy as a 12 word > phrase (could be a revision to BIP39 instead of a new BIP) > - Manual procedure is very simple, each derivation path can use a > shortened 256 word list which enjoys improved alphabetical > separation of words > - May prevent naive word selections which aren't limited to every > eighth word (similar to what checksum does) > - Can be extended further. For example, a 32 word phrase with the > same entropy as a 24 word phrase could also be added. We can keep > adding formats with unique word length and keep adding uses for the > meta data as needed. > -- You received this message because you are subscribed to the Google Groups "Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/20250524205608.D723F7C1191%40smtp.postman.i2p.
