new Trezor - question about Shamir backup vs legacy backup

[axel20]

I just got a Trezor Safe 3 and set it up last night. For the backup method, I chose the default selection of Shamir single share (20 words).  However, I've been thinking about it and I'm wondering if there is any advantage of using Shamir single share vs the legacy method?  I don't intend to upgrade to Shamir multi-share later and I know the biggest advantage of the Shamir method is being able to break up the seed into multiple shares that you can distribute, but I don't really want to do that.  This being the case, is there any advantage of sticking with Shamir single share vs the legacy 12 or 24 word method?

[Charles-Tim]

The shamir gave the option to have just a single share? Have you tried it and it worked? At least you suppose to have 2 or more shares. If it is a single share, then what is the point of having shimar as a backup plan.

If you do not need shamir purpose of backup, then just go for normal seed phrase backup directly. Go for segwit derivation path instead and not legacy. With segwit, you can save money on fees while making transactions.

[axel20]

The shamir gave the option to have just a single share? Have you tried it and it worked? At least you suppose to have 2 or more shares. If it is a single share, then what is the point of having shimar as a backup plan.

If you do not need shamir purpose of backup, then just go for normal seed phrase backup directly. Go for segwit derivation path instead and not legacy. With segwit, you can save money on fees while making transactions.

Yes, the single share is actually the default backup option.  I tried it out last night.  After backing up the wallet, I reformatted the Trezor and tried restoring it from the 20 word list and it worked.  I guess I'm not understanding the advantage of this over a regular 12 or 24 word backup.

[dkbit98]

I just got a Trezor Safe 3 and set it up last night. For the backup method, I chose the default selection of Shamir single share (20 words).  However, I've been thinking about it and I'm wondering if there is any advantage of using Shamir single share vs the legacy method?  I don't intend to upgrade to Shamir multi-share later and I know the biggest advantage of the Shamir method is being able to break up the seed into multiple shares that you can distribute, but I don't really want to do that.  This being the case, is there any advantage of sticking with Shamir single share vs the legacy 12 or 24 word method?

This new Shamir or SLIP39 is much more secure because there is no single point of failure, this is the biggest risk with using standard 12/24 seed phrase.
I see more wallets are adopting SLIP39 (Electrum, Blue Wallet, etc)  and I think this is going to be used by everyone in future.
There is nothing wrong with old format and you can continue using it if you want, 12 words is enough and you can add passphrases later.

You can find more information about SLIP39 here:
https://content.trezor.io/slip39
https://docs.trezor.io/trezor-firmware/core/misc/slip0039.html

PS
Note that Satoshilabs also created BIP39 standard that most wallets use today

[Charles-Tim]

Yes, the single share is actually the default backup option.  I tried it out last night.  After backing up the wallet, I reformatted the Trezor and tried restoring it from the 20 word list and it worked.  I guess I'm not understanding the advantage of this over a regular 12 or 24 word backup.

It has no advantage at all to the normal 12 to 24 word backups. The 12 word seed phrase is enough for your coins security. And as dkbit98 posted, you can add passphrase with it which has been the good option that I always go for while generating wallet. Seed phrase backup is advisable.

[axel20]

Yes, the single share is actually the default backup option.  I tried it out last night.  After backing up the wallet, I reformatted the Trezor and tried restoring it from the 20 word list and it worked.  I guess I'm not understanding the advantage of this over a regular 12 or 24 word backup.

It has no advantage at all to the normal 12 to 24 word backups. The 12 word seed phrase is enough for your coins security. And as dkbit98 posted, you can add passphrase with it which has been the good option that I always go for while generating wallet. Seed phrase backup is advisable.

Now that you mention this, is there any advantage at all over the 24 word backup to the 12?  I've heard that there's really not much difference in terms of security, but I see lots of comments from folks who subscribe to the "more words means more secure" mindset.

[Charles-Tim]

Now that you mention this, is there any advantage at all over the 24 word backup to the 12?  I've heard that there's really not much difference in terms of security, but I see lots of comments from folks who subscribe to the "more words means more secure" mindset.

The more the words, the longer it would take to brute force. That is the advantage. But both 12 and 24 words have 128 bits of security because bitcoin private key has 128 bits of security. The security which is enough for your coins protection.

[dkbit98]

It has no advantage at all to the normal 12 to 24 word backups.

Like I said, there is a BIG advantage, that is no single point of failure.
Here is one good blog post from Trezor that is answering many questions about SLIP 39, there is even instructions how to migrate from BIP39 to SLIP39:
https://blog.trezor.io/20-word-wallet-backup-your-questions-answered-bff078922644

Note that Trezor devices supporting SLIP39 are Trezor Safe 3 and Trezor Safe 5 and Model T.
Keystone hardware wallet is supporting Shamir but I am not sure if SLIP39 is fully supported.

[Charles-Tim]

Slip39 is not something new.

It has no advantage at all to the normal 12 to 24 word backups.

Like I said, there is a BIG advantage, that is no single point of failure.
Here is one good blog post from Trezor that is answering many questions about SLIP 39, there is even instructions how to migrate from BIP39 to SLIP39:
https://blog.trezor.io/20-word-wallet-backup-your-questions-answered-bff078922644

Note that Trezor devices supporting SLIP39 are Trezor Safe 3 and Trezor Safe 5 and Model T.
Keystone hardware wallet is supporting Shamir but I am not sure if SLIP39 is fully supported.

These are what axel20 (OP) posted:

I don't intend to upgrade to Shamir multi-share later and I know the biggest advantage of the Shamir method is being able to break up the seed into multiple shares that you can distribute, but I don't really want to do that.  This being the case, is there any advantage of sticking with Shamir single share vs the legacy 12 or 24 word method?

Yes, the single share is actually the default backup option.  I tried it out last night.  After backing up the wallet, I reformatted the Trezor and tried restoring it from the 20 word list and it worked.  I guess I'm not understanding the advantage of this over a regular 12 or 24 word backup.

He posted that if the share is just one, what is the advantage of slip39 over seed phrase. It has no advantage. No point of going for it.

Or instead of posting a link, discuss the advantages directly on your post.

[Saint-loup]

I just got a Trezor Safe 3 and set it up last night. For the backup method, I chose the default selection of Shamir single share (20 words).  However, I've been thinking about it and I'm wondering if there is any advantage of using Shamir single share vs the legacy method?  I don't intend to upgrade to Shamir multi-share later and I know the biggest advantage of the Shamir method is being able to break up the seed into multiple shares that you can distribute, but I don't really want to do that.  This being the case, is there any advantage of sticking with Shamir single share vs the legacy 12 or 24 word method?

No there is absolutely no advantage to get a 1 of 1 SLIP39 seed share over a standard BIP39 one as it has already been said. I even see one a disadvantage actually : your seed become incompatible with most wallets contrary to a normal seed. So if you need to use SLIP39 it's better to at least divide your seed into 2 seeds with 2 of 2 or 1 of 2 schemes, in order to at least getting some convenience and/or safety.