Bitcoin Forum

It seems Ian Coleman has quietly updated his famous page few days ago to offer a slip39 tool.

https://www.reddit.com/r/Bitcoin/comments/e6q6ij/slip39_web_tool_for_mnemonic_shares/

With this tool you can now split your keys in slip39 compatible shares.


https://github.com/satoshilabs/slips/blob/master/slip-0039.md

Interesting, thanks for sharing. Direct link here - https://iancoleman.io/slip39/

Bear in mind that SLIP39 should be seen as an alternative to BIP39, not as something to be built on top of it. The "Master Secret" has to be in hexadecimal format, so you can't directly split an existing seed phrase using this. If you wanted to use this to protect an existing wallet, then you would need to put your seed phrase in to https://iancoleman.io/bip39/, take the raw entropy in either hexadecimal or binary, and plug that in to https://iancoleman.io/slip39/ to generate the mnemonic shares (all on an airgapped machine, of course).

Also, don't confuse the passphrase on the SLIP39 page with any passphrase you might have already attached to your seed phrase. Although they essentially perform the same function of allowing plausible deniability, the SLIP39 passphrase is used to decrypt your master secret (in this case your entropy), whereas the BIP39 passphrase is used as part of the salt alongside your seed phrase to calculate your wallet's seed number.

He does have another Secret Sharing tool available here: https://iancoleman.io/shamir/
This one will accept any characters as the secret, but generates hexadecimal shares, rather than mnemonic shares.

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Mnemonic is a misnomer here, but it's the terminology he uses. You should obviously never rely on memory alone for BIP39 or SLIP39 phrases.

When testing my old Mnemonic seed on iancoleman, I got binary as entropy.

https://i.ibb.co/cT2fN6m/1.png

My Test Mnemonic seed :

binary:

I have to convert to Hex first before insert to Slip39
https://docs.google.com/spreadsheets/d/1NqJ1enUWL4diMVPXGa2jshLlm8qQw-avRJdoaTsx0eQ/edit#gid=0

and got my Hex

Then input it to https://iancoleman.io/slip39/  and got shared.

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I don't know why getting binary as entropy.

When generated new Mnemonic seed I got as hexadecimal already.
https://i.ibb.co/CVgc0NZ/2.png

I think it's just the default display option for the iancoleman site. There's no reason you can't display it as hex, which you did anyway with a converter (again, remember to do this all airgapped if doing it with your real seed!)

Having said that, you don't have to use hex, hex is just the highest base it will accept. You can quite as easily use the binary. The SLIP39 will still read the binary as hex, though, so you'll end up with a much larger number of words in each of your shares, which does increase the risk of making a mistake.

You can use this tool for mnemonic shares https://iancoleman.io/shamir39/
But unlike SLIP39, it's not a standardized format, so if the page disappears or its code change, you can lose your seed.
So you must archive the page when you use it.