Does encryption method still only support 1.3? And some other

[jyxjjj]

1. It seems no AES support, and there are 3 permissions missed.

2. Version larger than 1.3 needs a XML RDF tag object and i didn't successfully generated one.

3. Do you need ISO 32000-2:2020 File?

4. Same with Support for a built-in digital signature mechanism #969

[gettalong]

1. Yes, Prawn does not support AES encryption at the moment.
2. No, XML RDF tags are not needed for encryption.
3. The PDF 2.0 spec is freely available for everyone.