VirginMedia (large ISP in the UK) won't accept passwords longer than 10 characters. No spaces or special characters allowed, must contain a number, must start with a letter etc.
encoding\options\base64-salt\base64-hash-of-normalized-utf8
I keep the encoding/options so it can be backwards compatible on change... when an encoding/options isn't the current when the user logs in, it will be re-encoded/saved in the current... this is so that security can be upgraded over time.Run normalization on composite unicode characters & look-a-likes before encoding.
I do one thing some consider bad, which is strip leading/trailing whitespace which is more often a copy-paste error, not actual password entry.
Quoting from a reply I had: "As there's no account password quoted on the form you’ve filled in I'm unable to go in to any account specifics."
"accountPassword: I'm not giving you my password"
I guess it's a problem across the entire Virgin group of companies?