So got a new hardware wallet and thinking of using my own set of bip39 words instead of wallet generated one, combined with a passphrase.
Now, the reason for this is to ensure that I can recover/recreate my wallet even if I don’t have access to phrase seed paper backup( like when I am away from my home ).
So, I am thinking of generated phrase as follows:
get an 80 digit number( or even more). It’s a combination of 8 different mobile numbers of my family members/friends. It’s not random for me but random for others( at least I think so). Can be date of birth or a combination of number and DOB as well.
Use first two digits for the first phrase word.
Use the next there digits for the 2nd word, the next 3 digits for 3rd phrase word and so on for the next 11 words.
Till now, I have used 2+(11*3) = 35 digits. so, still 45 digits are remaining.
Use the next 4 digits (36th digit onwards) for 12th words( assuming it’s <= 2048) and so on for the 10 words, so total 11 4 digit words.
calculate checksum for 24th word. Coldcard now automatically calculates this.
Use a strong passphrase(15 chars alphanumeric) with no relation to this 80 digit number. pretty random.
My question is:
What issues do you see here. Do you think someone can guess this long number?
To me, it looks like it’s pretty difficult for someone to come up with this type of long number as there are billions of phone numbers. Also, I can always add different values to mobile numbers like DOB or email ids or something else that only I know.
And there is a passphrase that’s a completely different value with absolutely no relation to this long number.