Oooh, that's cool. I didn't realize Ian's support for cards looks so slick now! Thanks for the image. James On Wed, Feb 6, 2019 at 7:55 AM Alan Evans via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > Image didn't seem to attach: > [image: image.png] > > On Wed, 6 Feb 2019 at 09:48, Alan Evans wrote: > >> It's not quite enough to just do SHA512, you missed out this condition >> (incredibly rare as it is): >> >> > In case IL is 0 or ≥n, the master key is invalid. >> >> Also I can't see how I would use this to seed a hardware wallet that >> requires a BIP39 seed as mentioned in your abstract. >> >> For both of those reasons, you may want to just invent/formalize a scheme >> that takes Cards -> Entropy. >> From that Entropy one can generate BIP39, and non-BIP39 fans can just >> continue, generate and store their root xprv. >> >> Prior art: Note that Ian Coleman's BIP39 site already supports Cards (and >> Dice), see the logic here: >> https://github.com/iancoleman/bip39/blob/master/src/js/entropy.js >> >> [image: image.png] >> >> Note it detected "full deck". It also calculates the Total Bits of >> Entropy and can handle card replacement and multiple decks. >> >> PS, you're a bit out on your entropy calculation, log2(52!) ~= 225.58 >> bits, not 219. >> >> >> On Tue, 5 Feb 2019 at 02:08, Devrandom via bitcoin-dev < >> bitcoin-dev@lists.linuxfoundation.org> wrote: >> >>> I would suggest 50+ 6-sided dice rolls, giving about 128 bits of >>> entropy. Compared to a shuffle, it's easier to be sure that you got the >>> right amount of entropy, even if the dice are somewhat biased. >>> >>> >>> On Mon, Feb 4, 2019 at 2:33 PM James MacWhyte via bitcoin-dev < >>> bitcoin-dev@lists.linuxfoundation.org> wrote: >>> >>>> >>>> James >>>> >>>> >>>> On Sun, Feb 3, 2019 at 10:27 AM Ryan Havar via bitcoin-dev < >>>> bitcoin-dev@lists.linuxfoundation.org> wrote: >>>> >>>>> Conveniently a shuffled deck of cards also can serve as a physical >>>>> backup which is easy to hide in plain sight with great plausible >>>>> deniability. >>>>> >>>> >>>> To make sure someone doesn't play with your cards and mix up the order, >>>> use a permanent marker to draw a diagonal line on the side of the deck from >>>> corner to corner. If the cards ever get mixed up, you can put them back in >>>> order by making sure the diagonal line matches up. >>>> _______________________________________________ >>>> bitcoin-dev mailing list >>>> bitcoin-dev@lists.linuxfoundation.org >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>>> >>> _______________________________________________ >>> bitcoin-dev mailing list >>> bitcoin-dev@lists.linuxfoundation.org >>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>> >> _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >