The best passphrase

[apogio]

By the way, my conversation with o_e_l_e_o above intrigued me and I started reading some papers in regards with bitcoin's security level. I will not add them here, but I will, instead, add this topic I found https://bitcointalk.org/index.php?topic=2859033.0 which explains what o_e_l_e_o said above in more details, in case anyone is interested.

[o_e_l_e_o]

Ps. I am not sure whether all these 93 characters can be used but if I recall correctly they can, I am just busy at the moment and I can't check online. If someone could confirm this please

BIP39 actually specifies that any passphrase will be normalized to UTF-8 NFKD, so you can actually have a character set in the tens of thousands if you wanted, provided your wallet software supports these characters, and use any unicode character such as ½, Ü, or ←.

I wouldn't recommend going down this route, however, since there are a lot of unicode characters that look very similar or even identical, and would obviously lead to completely different wallets if confused. For example A, A and A are all different characters (Latin, Greek, and Cyrillic).

[apogio]

Ps. I am not sure whether all these 93 characters can be used but if I recall correctly they can, I am just busy at the moment and I can't check online. If someone could confirm this please

BIP39 actually specifies that any passphrase will be normalized to UTF-8 NFKD, so you can actually have a character set in the tens of thousands if you wanted, provided your wallet software supports these characters, and use any unicode character such as ½, Ü, or ←.

I wouldn't recommend going down this route, however, since there are a lot of unicode characters that look very similar or even identical, and would obviously lead to completely different wallets if confused. For example A, A and A are all different characters (Latin, Greek, and Cyrillic).

Yeah, I wouldn't go down this path.

The dataset I will use is:

A - Z (excluding O and I) -> 24 characters
a - z (excluding l) -> 25 characters
0 - 9 (excluding 0) -> 9 characters
@#$%^&* -> 7 characters

So in total I have 65 characters.

I plan to go for more than 20 characters long passphrases, which will give me ENTROPY > ln(65^20)/ln(2) ~= 120 bits.

I will collect random data using the following command:

Code:

cat /dev/urandom | tr -dc 'ABCDEFGHJKLMNPQRSTUVWXYZ123456789abcdefghijkmnopqrstuvwxyz@#$%^&*' | fold -w 20 | head -n 1

[Saint-loup]

I have been thinking of the best way of adding a passphrase to a wallet I want to create, but I do not know the passphrase I can use that will be impossible to brute force.

What comes to my mind is by generating a seed phrase which I will use as passphrase. Open electrum wallet, the wallet to create another seed phrase for me, add a passphrase to it which is the first seed phrase another wallet created for me.

The first seed phrase is my passphrase
The second seed phrase is my seed phrase
The second seed phrase and my passphrase (first seed phrase) create private keys and addresses for me which should be safer than just using a seed phrase without passphrase.

I am think of the way to use the passphrase, which one is difficult to brute? By writing the words together and not give space in between, or by seperating the words?

This should be a secure wallet if I do not have the seed phrase backup together with the passphrase but differently. I am thinking if seed phrase with space is secure enough, it should also secure if used as passphrase?

Is there others ways to have a more secure passphrase in a way the world would have extinct before anyone can brute force it.

I don't think it's a very bad idea tbh even if it prevents the ability of being memorized for a long time like a common passphrase, but since you don't need any checksum computation for it why using a computer and a software(along with an OS), potentially infected or bugged, without being sure of their reliability while you can use a safe way to do that and hence adding robustness to your seed? If I were you, I would just use physical dices in order to randomly pick words from the BIP39 list. The list is numbered. https://github.com/bitcoin/bips/blob/master/bip-0039/english.txt