Net::Xero 0.044 and earlier for Perl uses the rand() function as the default source of entropy, which is not cryptographically secure, for cryptographic functions. Specifically Net::Xero uses the Data::Random library which specifically states that it is "Useful mostly for test programs". Data::Random uses the rand() function.

• https://metacpan.org/release/BAREFOOT/Data-Random-0.13/source/lib/Data/Random.pm#L537
• https://metacpan.org/release/ELLIOTT/Net-Xero-0.44/source/lib/Net/Xero.pm#L58
• https://metacpan.org/release/ELLIOTT/Net-Xero-0.44/source/lib/Net/Xero.pm#L9
• https://perldoc.perl.org/functions/rand
• https://security.metacpan.org/docs/guides/random-data-for-security.html