Should I convert my 12 word seeds into 13 word seeds?

[Bizmark13]

Now that the new version of Electrum recommends 13 word seeds, would it be a good idea to convert both my 12 word seeds into 13 word ones? Are there any security implications for doing this manually as opposed to generating a new seed automatically? Could (should?) I choose a word from the Electrum dictionary and simply append it to the end of my existing seed to turn it into a 13 word seed?

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[ThomasV]

see http://bitcoin.stackexchange.com/questions/36582/why-are-electrum-2-x-mnemonic-sentences-thirteen-words-long

[btchris]

Now that the new version of Electrum recommends 13 word seeds, would it be a good idea to convert both my 12 word seeds into 13 word ones? Are there any security implications for doing this manually as opposed to generating a new seed automatically? Could (should?) I choose a word from the Electrum dictionary and simply append it to the end of my existing seed to turn it into a 13 word seed?

You can't convert an old-style seed with 12 words into a new-style seed with 13 words -- the two are completely different beasts. AFAIK, the old-style seeds will continue to be supported indefinitely.

The only potential advantages I could see (and they're pretty minor) of a new-style seed from an end-user's point of view would be:

• A larger gap limit, by default (not all that useful, given that you can increase the gap limit manually if you have a need for it).
• Some compatibility with other wallets, for example you can export a master public key from a new-style wallet into a Mycelium for Android wallet (to create a watching-only wallet)... not really much advantage since you can already do that with Electrum for Android.
• Easier to recover a mistaken word or two; if you're in the habit of trying to memorize your seed (not something I'd ever suggest), new-style seeds are easier to recover if you're off by a word or two.

Of course there are many other improvements in Electrum 2.x in terms of other new wallet types, but if you're only interested in having a standard wallet, there isn't a strong argument to create a new-style wallet to replace your old-style one (I stand to be corrected though).

[Bizmark13]

Thanks for the replies.

see http://bitcoin.stackexchange.com/questions/36582/why-are-electrum-2-x-mnemonic-sentences-thirteen-words-long

So I take it that the extra word wasn't put in there to increase the entropy/strength then? It's just there to tell you what version of Electrum was used to generate the seed?

Now that the new version of Electrum recommends 13 word seeds, would it be a good idea to convert both my 12 word seeds into 13 word ones? Are there any security implications for doing this manually as opposed to generating a new seed automatically? Could (should?) I choose a word from the Electrum dictionary and simply append it to the end of my existing seed to turn it into a 13 word seed?

You can't convert an old-style seed with 12 words into a new-style seed with 13 words -- the two are completely different beasts. AFAIK, the old-style seeds will continue to be supported indefinitely.

The only potential advantages I could see (and they're pretty minor) of a new-style seed from an end-user's point of view would be:

• A larger gap limit, by default (not all that useful, given that you can increase the gap limit manually if you have a need for it).
• Some compatibility with other wallets, for example you can export a master public key from a new-style wallet into a Mycelium for Android wallet (to create a watching-only wallet)... not really much advantage since you can already do that with Electrum for Android.

Ah, OK, that makes sense.

• Easier to recover a mistaken word or two; if you're in the habit of trying to memorize your seed (not something I'd ever suggest), new-style seeds are easier to recover if you're off by a word or two.

Of course there are many other improvements in Electrum 2.x in terms of other new wallet types, but if you're only interested in having a standard wallet, there isn't a strong argument to create a new-style wallet to replace your old-style one (I stand to be corrected though).

Why would you advise against trying to memorize an Electrum seed? I currently use two seeds and have memorized them both despite never trying to do so. It just happened naturally. I always assumed that memorizing it would probably safer than writing it down and even a partial seed would be enough to restore the wallet (since I remember hearing from somewhere that even having only half of the seed available would cut down the time required to crack the rest of it to mere days/weeks).

[btchris]

So I take it that the extra word wasn't put in there to increase the entropy/strength then? It's just there to tell you what version of Electrum was used to generate the seed?

Right, it doesn't increase the entropy, it's there to make it possible to detect if a seed is valid or not. If you mistype a word during a restore, it can (with a 99.6% probability) detect that your seed is invalid and warn you.

Why would you advise against trying to memorize an Electrum seed?

Because I'm old and forgetful?

Seriously though, I only meant that I think it's foolish to depend only on your memory to protect your bitcoin funds. I see no problem if you also have it stored (in hard copy) safely.

[ThomasV]

The number of words in the seed phrase increased from 12 to 13 because a checksum was included in the seed.
In the future, we will probably use a better wordlist (with more words), and seed phrases will go down to 12 words.
So please do not rely on the number of words in the seed to detect old / new wallets.