[jose] RSA-OAEP vs RSA-OAEP-256

[Sergey Beryozkin <[e-mail]>]

Hi Everyone

I'm contributing to a project where `RSA-OAEP`  [1] is currently a default
key encryption algorithm for encrypting JWT claims and we've had a request
to replace it with `RSA-OAEP-256` because `SHA-1` is used in `RSA-OAEP`.

I'd like to ask the experts, why does `RSA-OAEP` have a `Recommended+`
status, while `RSA-OAEP-256` - optional, at [1] ?

Also, while it is not a JOSE specific question, I'd appreciate some
comments on whether having an 'SHA-1' element in the `RSA-OAEP` encryption
process makes `RSA-OAEP` less secure or not. My basic understanding, based
on some Web search results, is that `RSA-OAEP` remains a secure algorithm.

Thanks, Sergey

[1] https://tools.ietf.org/html/rfc7518#section-4.3%5BRSA-OAEP%5D