Amon2::Auth::Site::LINE uses the String::Random module to generate nonce values.  String::Random defaults to Perl's built-in predictable random number generator, the rand() function, which is not cryptographically secure

• https://metacpan.org/release/SHLOMIF/String-Random-0.32/source/lib/String/Random.pm#L377
• https://metacpan.org/release/TANIGUCHI/Amon2-Auth-Site-LINE-0.04/source/lib/Amon2/Auth/Site/LINE.pm#L235
• https://metacpan.org/release/TANIGUCHI/Amon2-Auth-Site-LINE-0.04/source/lib/Amon2/Auth/Site/LINE.pm#L255
• https://security.metacpan.org/docs/guides/random-data-for-security.html