About authentication methods: Update


A month ago, I questioned the value of newer authentication methods, in particular SCRAM-SHA-*, compared to simple PLAIN authentication over TLS, and concluded with "I really hope I'm wrong". Well, the good news is: I was wrong!

Here are the main points that convinced me:

These two points are enough to actually reverse my point of view completely: ideally every service should offer only SCRAM-SHA-* authentication and drop support for PLAIN and others, to enforce that these benefits become ubiquitous.

My thanks to everyone who sent me comments and helped to convince me!

Also, to clarify: with GNU SASL, msmtp and mpop support SCRAM-SHA-1 and in the next version will also support SCRAM-SHA-256.

Update 2021-01-30: This does not mean that SCRAM-SHA-* is without flaws. See this comment by Simon Josefsson, who is an expert in these matters.

Update 2021-06-15: Simon Josefsson wrote an article about authentication mechanisms. It highlights problems with SCRAM, but also points out that SCRAM addresses some shortcomings of simpler mechanisms such as PLAIN.