Electrum Seed Phrase Reduce from 12 to 11. How Possible is it?

[uche6215]

I opened Electrum wallet and got the address last year and the seed phrase was 12 which I also wrote it down in a save place and along the line I changed device so I downloaded Electrum wallet app again in the new device and this morning I was trying to create the wallet and it asked me to enter the seed phrase which I entered the one I wrote down but it wasn't accepted and it was 12 words then I was deleting them to rewrite it again but to may surprised. After deleted one full word and deleted the first later of the second word, it was accepted that it is the correct word which is 11 seed word.

So I want to know if it is possible or it is that I have mistakenly entered another person seed phrase? Though the wallet is empty. I will like to know more. Thanks.

[OmegaStarScream]

I don't believe that's possible. You're saying you typed 11 words, and the button is now clickable. Have you checked if that resulted into the same address as yours?

You're not going to "take anyone's wallet" even if its accepted, but I also don't think that Electrum would accept 11 words as a valid seedphrase to start with.

[Hazink]

Are you sure you downloaded the right electrum wallet from https://electrum.org/#home?

This is the first time I've come across a wallet that makes use of only 11 seed phrases because all I know about is 12 and 24 word seed phrases. I will advise you to redownload the wallet from the right source and try again.

And I hope your seed phrase hasn’t been exposed to danger.

[Mia Chloe]

Seed phrases can be extended to above 12 with custom words . Also they can't be reduced to 11.
Either you miscounted or the suggestion electrum gave which happened to be the last word was picked by you unknowningly.

[Charles-Tim]

I don't believe that's possible. You're saying you typed 11 words, and the button is now clickable. Have you checked if that resulted into the same address as yours?

If it is Electrum seed phrase, it will not work. If it is BIP39 seed phrase, it works and it will generate the keys and addresses. I tried it now on my laptop and all letters and words as seed phrase will generate you keys and addresses on Electrum if you choose BIP39. Just like using a custom word as seed phrase. Not recommended.

Edit:
Read hosseinimr93 post below which answer your question correctly.

So I want to know if it is possible or it is that I have mistakenly entered another person seed phrase?

No

Go for the 12 words which will generate your own keys and addresses for you.

[promise444c5]

~

Electrum will always generate  12 words by default unless you want to extend it by add custom words... I don't know how you did it but try checking  you might be seeing two words as a single word from your side or maybe you entered an extra word probably a repition in a word,might be when you were copying it.

[hosseinimr93]

You porbably wrote down your seed phrase incorrectly and that's why your 12 word seed phrase isn't valid.
Do you still have access to your old computer? If so, open your wallet there and export your seed phrase.

You're not going to "take anyone's wallet" even if its accepted, but I also don't think that Electrum would accept 11 words as a valid seedphrase to start with.

It's technically possible to have a valid 11 word electrum seed phrase. You can even have an electrum seed phrase with any other number of words.

Here is a valid 11 word electrum seed phrase.

Code:

resist raccoon monkey science enjoy ensure eight shy brush fall ice

A valid 10 word electrum seed phrase:

Code:

uniform slim shed sadness mask alone pledge multiply tip collect

A valid 2 word electrum seed phrase:

Code:

black about

A valid 30 word electrum seed phrase:

Code:

tuition decorate reduce aisle canyon carpet offer salt fruit clump another adapt display super mirror curve random invite deputy donkey ordinary speak artist empty book ship flock resist hazard midnight

[AB de Royse777]

I opened Electrum wallet and got the address last year and the seed phrase was 12 which I also wrote it down in a save place and along the line I changed device so I downloaded Electrum wallet app again in the new device and this morning I was trying to create the wallet and it asked me to enter the seed phrase which I entered the one I wrote down but it wasn't accepted and it was 12 words then I was deleting them to rewrite it again but to may surprised. After deleted one full word and deleted the first later of the second word, it was accepted that it is the correct word which is 11 seed word.

So I want to know if it is possible or it is that I have mistakenly entered another person seed phrase? Though the wallet is empty. I will like to know more. Thanks.

If your original seed that was written down and the seed you used to open the wallet are not same then you opened a different wallet. Without having the exact letters and words with same sequence you will not be able to open the same wallet.

Opening the wallet with 11 words is impossible. You made mistake somewhere.

[nc50lc]

-snip-
After deleted one full word and deleted the first later of the second word, it was accepted that it is the correct word which is 11 seed word.

So I want to know if it is possible or it is that I have mistakenly entered another person seed phrase? Though the wallet is empty. I will like to know more. Thanks.

That is totally possible in Electrum with a very low chance.

Even if the first letter of the second word and the whole first word are removed, Electrum will still proceed to check if the provided seed phrase has a valid "version number".
If it resulted with "0x01", "0x100" or "0x101" as first few Bytes, it will take the seed phrase as a valid and will let you create a wallet with it.

And no, that's not another person's wallet.
It's just pretty easy to come across a valid seed phrase that doesn't have a "correct word" since Electrum doesn't actually require to use its word list.
It uses those words by default when generating a seed phrase.
e.g.: Try to delete 11 words from your seed phrase and type "a" continuously, somewhere along the long "aaaaaaaa...",
you'll eventually be able to click "next" when the seed phrase produces a valid seed version.
e.g.:

Code:

banana aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

[promise444c5]

And no, that's not another person's wallet.
It's just pretty easy to come across a valid seed phrase that doesn't have a "correct word" since Electrum doesn't actually require to use its word list.

So it gets an existing random wallet(not owned by someone) or it gets
a new one  entirely??...tried it with 11 words and any char same with 1 word and any char  it got me a wallet, the first was a segwit the second was a standard  wallet..which means I can use that wallet for transactions and I did try doing a test transaction  and it worked

[hosseinimr93]

So it gets an existing random wallet(not owned by someone) or it gets
a new one  entirely??

If you entered 11 truely random words and now have a valid electrum seed phrase, your seed phrase provides 121 bits of entropy. That's secure enough and it's impossible that someone has generated the same wallet before or someone generate the same wallet in the future.

[promise444c5]

If you entered 11 truely random words and now have a valid electrum seed phrase, your seed phrase provides 121 bits of entropy. That's secure enough and it's impossible that someone has generated the same wallet before or someone generate the same wallet in the future.

I noticed something  too ,Segwit type of seed phrase has a seed combination format(or I'm just mistaken )on electrum, if it could probably  determine the segwit type without the complete seed phrase inserted then there're some particular combination  to show that the wallet is a segwit type the min-combination is what I don't seem to get....so with the minimum combination + random chars I should be able to generate a segwit type wallet.

[hosseinimr93]

I noticed something  too ,Segwit type of seed phrase has a seed combination format(or I'm just mistaken )on electrum, if it could probably  determine the segwit type without the complete seed phrase inserted then there're some particular combination  to show that the wallet is a segwit type the min-combination is what I don't seem to get....so with the minimum combination + random chars I should be able to generate a segwit type wallet.

Wrong.

Each electrum seed phrase contains a version number.
The version number is the first 8 or 12 bits of the hash of the seed phrase and it determines the seed type.

To calculate the version number, the whole seed phrase is required and there is no way to know the seed type just with knowing a part of the seed phrase.

The version number is 0x01 for legacy seed phrases, 0x100 for segwit seed phrases and 0x101 for 2FA seed phrases.
If you hash the seed phrase and it doesn't start with 01, 100 or 101, it's not valid.

[promise444c5]

The version number is 0x01 for a legacy seed phrases, 0x100 for segwit seed phrases and 0x101 for 2FA seed phrases.
If you hash the seed phrase and it doesn't start with 01, 100 or 101, it's not valid.

Okay noted this..

[SilverCryptoBullet]

Opening the wallet with 11 words is impossible. You made mistake somewhere.

With Electrum wallet, when importing a wallet seed phrase for wallet recovery, with each word, when OP types a first character of a word, the wallet software will display a list of possible words start with that first character.

Assume I type 's' as a first character for a first word, the list will appear with some words to choose like

Code:

sad
saddle
sadness
safe
said
sail
salad
salmon
and so on

OP can try The FinderOuter, a bitcoin recovery tool offline.

If OP still has access to that wallet, I recommend to move bitcoin to a new wallet (create a new wallet, write down wallet seed carefully, test it for recovery to avoid similar problem with this current wallet,  move bitcoin to a new wallet). Then OP can try to use FinderOuter with the wallet in trouble.

[nc50lc]

And no, that's not another person's wallet.

So it gets an existing random wallet(not owned by someone) or it gets
a new one  entirely??

With or without existing transaction, that's a new wallet.
Unless if the exact same seed phrase that you manually created is already used by someone else which is highly unlikely for 11 words + 1 "cdrwfehvsdw..".
If an existing wallet with a "normal" Electrum seed, that's only if the computed seed collides with your seed which has even lower chance of happening.

Although, I will not say that it's 100% a new wallet since seed phrase generation relies on the fact that the words or entropy used is unique which has finite number of combinations.
It's more of "almost impossible" that it would never happen.

I noticed something  too ,Segwit type of seed phrase has a seed combination format(or I'm just mistaken )on electrum, if it could probably  determine the segwit type without the complete seed phrase inserted then there're some particular combination  to show that the wallet is a segwit type the min-combination is what I don't seem to get....so with the minimum combination + random chars I should be able to generate a segwit type wallet.

It's about the reserved "version number" that I mentioned in my reply above which is the first 2~3Characters of HMAC-SHA512("Seed version",<normalized mnemonic seed>)
Link to code: github.com/spesmilo/electrum/blob/295ea97f1f94b916fe5304098bb005505e4f28ed/electrum/mnemonic.py#L243

I'll just provide some examples to explain it in detail:

For example; my example seed phrase above has a reserve number of 0x01 which is for standard wallet.

Code:

banana aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

Result HMAC-SHA512("Seed version",<words above>):

Code:

01853021fd65bee2583eaa7b255fc6f0e1b0a879abac59ed7b5169913a1e3ce0be2a8174298ad15ec8d668befa5097ddd313fcf4ebea5433a7beefb50af10012

First character is 0, so the length is 0+2 = 2 characters.
Version number (first 2 Characters of the above):

Code:

01

0x01 is the reserved number for "Standard" Electrum seed.
SegWit Example;

Code:

monkey yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy

Result HMAC-SHA512("Seed version",<words above>):

Code:

1004fea6c8adc0bd04517fca04b1333c4e36f873885dd2a4d054497fcd01fcbbc767b2fd8a535437e2d61e0f39d73cda9c77432d7ab51586d6ca51fc4bedcce7

First characters is 1, so the length is 1+2 = 3 characters.
Version number (first 3 Characters of the above):

Code:

100

0x100 is the reserved number for "SegWit" Electrum seed.

So the gist is: if any jargon you type as seed phrase produced a valid reserve number when passed through HMAC-SHA512 with the string "Seed version" as key.
It's a valid Electrum seed. (it's not recommended to use it though)

[hosseinimr93]

If OP still has access to that wallet, I recommend to move bitcoin to a new wallet (create a new wallet, write down wallet seed carefully, test it for recovery to avoid similar problem with this current wallet,  move bitcoin to a new wallet).

If OP still has access to the wallet on the old device, he can simply export the seed phrase and write it down again (this time, correctly).
There is no need to make a new wallet, if the only purpose is to have an electrum wallet that its seed phrase has been written down somewhere correctly.

[Mia Chloe]

(it's not recommended to use it though)

This thread just gave me a clearer understanding of the whole seed phrase stuff though I still have a couple of questions like ; Why is it not recommended to make use of the custom generated seed like the example you gave.
And would such a seed be considered as a custom electrum seed?

[khaled0111]

Why is it not recommended to make use of the custom generated seed like the example you gave.

Probably, for the same reason why people don't use brain wallets anymore and for the same reason why it's recommended to use long random passwords instead of ones you can easily remember.
You shouldn't do it because it's not safe.
A custom seed or password is easier to predict (if you can think of it then someone else can too) unlike randomly generated seeds/passwords.

[BitMaxz]

Probably, for the same reason why people don't use brain wallets anymore and for the same reason why it's recommended to use long random passwords instead of ones you can easily remember.
You shouldn't do it because it's not safe.
A custom seed or password is easier to predict (if you can think of it then someone else can too) unlike randomly generated seeds/passwords.

How about you made a custom seedphrase and the seed phrase you generated on Electrum is the same as you just made?
What are these are safe the generated one or the custom seed you created?

For me, anyone can guess what you seed phrase is the only way to avoid someone to guess your seed phrase is to use extra word or adding passphrase to protect your wallet but wallets that generated only 12 words still not easy to guess however, it still possible that someone can guess it that is why they added other security option to protect your wallet and seed like multisig or extra word/passphrase.