SCRAM-SHA-1(-PLUS) + SCRAM-SHA-256(-PLUS) supports

[Neustradamus]

"When using the SASL SCRAM mechanism, the SCRAM-SHA-256-PLUS variant SHOULD be preferred over the SCRAM-SHA-256 variant, and SHA-256 variants [RFC7677] SHOULD be preferred over SHA-1 variants [RFC5802]".

There is only SCRAM-SHA-1, there is not SCRAM-SHA-1-PLUS:

• https://tools.ietf.org/html/rfc5802
• https://tools.ietf.org/html/rfc6120

There is not SCRAM-SHA-256(-PLUS):

• https://tools.ietf.org/html/rfc7677 since 2015-11-02
• https://tools.ietf.org/html/rfc8600 since 2019-06-21: https://mailarchive.ietf.org/arch/msg/ietf-announce/suJMmeMhuAOmGn_PJYgX5Vm8lNA

I add SCRAM-SHA-512(-PLUS): https://xmpp.org/extensions/inbox/hash-recommendations.html

Linked to:

• https://github.com/euroelessar/jreen/issues/43
• https://github.com/scram-xmpp/info/issues/1