Preface: I am not an expert in encryption, so sorry for any inaccuracies with how I am describing the issue here.

In the documentation, it states:

// Note: CBC and ECB modes use PKCS#7 padding as default

Is it possible to configure what padding is used? I am working with a system where they are not expecting padding. Is that something that even makes sense/is possible?

At the third paragraph on the section Preface, there is a typo on the acronym.

From this book you will learn how to use cryptographic algorithms and cryptosystems like hashes, MAC codes and key derivation functions (KFD)

Here, KFD should be KDF.

If multiple requests are submitted for the same host/port - any new ones are ignored.

Such a scenario it would be useful to handle it better would be to either extend or shorten the timeout.

... looking through how it works, it looks like if you add '-!' to the ipset command, it will overwrite the previous value.

Perhaps the '-!' option should be indicated in the sample for ipset integrat

To check that all newtypes (SecretKeys, Poly1305, etc.) implement the correct traits, new testing functions are needed.

For example fn test_traits_secret_key<Secret: Debug + Drop + PartialEq>() {} could be used to check that a secret key implements the needed traits.