A good implementation and documentation for passphrases is Coldcard.
https://coldcard.com/docs/passphrase/
Using passphrases makes it possible to generate approximately 5.9 × 10197 different wallets based on your original seed words.
Passphrases must be:
- No longer than 100 characters.
- ASCII characters only (no accented letters)
- Upper case letters
- Lower case letters
- Numbers
- Symbols
How did you derived 5.9 × 10197 ?
ASCII has 128 symbols.
With 100 allowed that would give 128^100 combinations and that is without all combination using less than all 100 characters.
It’s an excerpt from the Coldcard article I linked to. They didn’t explain how.
I imagine it is the number of combinations 100 ASCII characters can produce, but that’s just a guess.
Aha:
5.9 × 10^197 is already a number I can better agree to.
Plain cooy/paste gives 5.9 × 10197 😁
