BTC Wallets supporting SLIP39

[dkbit98]

SLIP39 or Secret Shamir Sharing is made by same Trezor developers who made widely used BIP39 format.
They made some improvements with changing the list of words and their number to 20, instead of standard 12/24 that is used for BIP39.
There are 1024 words in SLIP39 WordList and you can find it released on trezor github.

I won't get technical here but you can find more information about SLIP39 on github and trezor website.
You can use SLIP39 as a single backup with 20 words, or as multi backup that makes them much safer and harder to lose.

Bitcoin wallets currently supporting SLIP39:

• Electrum
• Sparrow wallet
• Blue wallet ^mobile
• Trezor ^HW
• Keystone ^HW

I am focusing only on Bitcoin wallets here, but there are also some altcoin ethereum wallets that support SLIP39 format.

If you know for sure any other siftware and hardware wallet that support SLIP39 please report in here.

[Kruw]

For those wanting to integrate SLIP39, here's a C# library for it created by Wasabi's lead maintainer: https://github.com/lontivero/Slip39

[dkbit98]

I am adding few more tools that can be useful for anyone using SLIP39 format.
Everyone know about IanColeman Mnemonic Code Converter website, but he also created a tool for splitting and combining SLIP39 mnemonics phrases.
Note that this is experimental prototype, but everything is posted as open source and can be inspected:
https://iancoleman.io/slip39/
https://github.com/iancoleman/slip39

Another python tool can be used for converting BIP39 into SLIP39.
This is again released as open source tool:
https://slip39.com/
https://github.com/pjkundert/python-slip39

[Saint-loup]

Unfortunately Electrum doesn't allow to generate a SLIP39 seed or to divide an existing one afaik. The Ian Coleman tool doesn't allow to create a mnemonic seed splitted or to divide an existing one either. It only takes or creates a seed/key in hexadecimal format. So do you know a SLIP39 tool allowing to split an existing bip39 mnemonic seed into several shares or to generate one at least?
SLIP39 can be useful to safely spread a seed through several places, even online without the threat of being found and stolen by someone else.

[nc50lc]

Unfortunately Electrum doesn't allow to generate a SLIP39 seed or to divide an existing one afaik.

The problem is, those two standards' mnemonic to seed algorithm don't mix well because wallets use SLIP39's master secret as seed while BIP39 mnemonic is hashed to generate its seed.
Given that, there's a workaround if you really want to use an existing BIP39 mnemonic to create SLIP39 shares. (below)

So do you know a SLIP39 tool allowing to split an existing bip39 mnemonic seed into several shares or to generate one at least?

There's a workaround in Iancoleman's BIP39 and SLIP39 tools that can do that
But your SLIP39 shares will be too long since it'll be using the 512-bit seed derived from the BIP39 mnemonic as its "Master secret".

The workaround is to get your existing BIP39 mnemonic's seed:
In BIP39 tool; paste your BIP39 mnemonic on "BIP39 Mnemonic" text box (and your passphrase), then copy the result "BIP39 Seed".
In SLIP39 tool; paste the copied seed on "Master Secret" and set your 'Groups and Members' preferences.

Then try the shares on a SLIP39-compatible wallet like Electrum if it will restore the same private keys and addresses.
Note: Don't rely on workarounds if you want a reliable backup.

[Saint-loup]

That's an interesting workaround, unfortunately it doesn't allow to get back the initial mnemonic seed. Mnemonic shares are a bit long indeed but I could get with that. What I was looking for actually was the same tool as the Ian Coleman's Shamir39 tool, allowing to get shares into a mnemonic format from a BIP39 seed also in a mnemonic format but I understand it doesn't exist with SLIP39. It's sad they still haven't standardized a protocol allowing to do that. I don't want to rely on an isolated tool. When we want to use it there is even a big disclaimer written in red saying"There are no alternative implementations, meaning you are totally dependent on this tool if you use it. That is a dangerous situation to be in.  

[nc50lc]

What I was looking for actually was the same tool as the Ian Coleman's Shamir39 tool, allowing to get shares into a mnemonic format from a BIP39 seed also in a mnemonic format but I understand it doesn't exist with SLIP39. -snip- I don't want to rely on an isolated tool.

Yeah, it's a good thing that the big red warning above iancoleman's shamir39 tool is hard to miss.

It's sad they still haven't standardized a protocol allowing to do that.

Bad new is: I think it's impossible to create a standard for this that's also compatible with SLIP39 standards without changing BIP39.
The main reason is it's nearly impossible to get the mnemonic back from the seed since it's a product of 2048 rounds of HMAC-SHA512 algorithm which is considered one-way.
so: mnemonic seed (BIP39) -> seed -> mnemonic seed (SLIP39) is possible, but not:
    mnemonic seed (SLIP39) -> seed -x- mnemonic seed (BIP39)

And changing a standard to implement another standard defeats the purpose of "standards".