where in the RFC is secret's padding

[pyramation]

Hello. Thanks for this library!

https://github.com/yeojz/otplib/blob/dab816b2faf6657c2e2d7e8e91391511c743a07c/packages/otplib-core/src/totp.ts#L92-L109

Referencing these lines, it looks like you're copying the secret's buffer data until it fills the required size. Maybe I'm missing something from the totp or hotp RFC where I can read some documentation where this particular part of the code is based on? I'm learning TOTP and this library and wanted to understand where this particular part of the algorithm is described.

https://tools.ietf.org/html/rfc6238 here is doesn't seem they pad the secret. Is the padding something that happened in the industry, but not necessarily the standards?

Thanks in advance!