Net::Dropbox::API 1.9 and earlier for Perl uses the rand() function as the default source of entropy, which is not cryptographically secure, for cryptographic functions. Specifically Net::Dropbox::API 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/NORBU/Net-Dropbox-API-1.9/source/lib/Net/Dropbox/API.pm#L11
• https://metacpan.org/release/NORBU/Net-Dropbox-API-1.9/source/lib/Net/Dropbox/API.pm#L385
• https://perldoc.perl.org/functions/rand
• https://security.metacpan.org/docs/guides/random-data-for-security.html