Basic認証の最大文字数
ユーザ名は255byte以内(":"は使えない)。以下、manページより。
$ man htpasswd .... RESTRICTIONS On the Windows and MPE platforms, passwords encrypted with htpasswd are limited to no more than 255 characters in length. Longer passwords will be truncated to 255 characters. The MD5 algorithm used by htpasswd is specific to the Apache software; passwords encrypted using it will not be usable with other Web servers. Usernames are limited to 255 bytes and may not include the character :. Apache HTTP Server 2003-11-25 HTPASSWD(1)