All UTF-8 characters for generated passwords

Question

Why do a lot of password generators don't generate strong passwords including chinese, arabian...-characters? All generators I saw, also the included one in my password manager keepass, just output characters that are related to western languages.

In some cases would it be understandable, if the user

• needs to type his password manually into the computer
• doesn't now how to enter such characters.

Also some characters have nearly the same shape which could leed to confusion, because the input looks right, but the characters have the wrong UTF-8 code.

Uses of a password manager would not encouter the listed problems or are there other aspects to consider?

Answer 1

To answer your two specific examples:

1. Most Western computer systems don't have fonts with complete coverage of CJK characters, and when they do, the appearance isn't always correct. Having a password displayed to you as a series of boxes isn't particularly useful, and worse, some programs will replace those un-displayable characters with substitutes, mangling your password.
2. Arabic, in addition to the missing-coverage problem, has an additional problem that characters change their appearances depending on what characters they're written next to. Not all programs implement this correctly.

In short, it's better to stick with characters that are known to work almost universally (the ASCII subset of Unicode) and make up for the lack of variety with an increased length.