IMAP authentication by Mutt: Is Mutt transmitting password in plaintext?

Question

I have recently started using mutt to access my email account via IMAP.

My IMAP connection settings are as follows:

set ssl_starttls = yes
set ssl_force_tls = yes
set imap_user = "[email protected]"
set smtp_url = "smtp://[email protected]@smtp.domain.tld:[port]/"
set folder = "imaps://imap.domain.tld:[port]"
set hostname = domain.tld

I have not stored my password so I have to type in my password every time I login

When I start mutt I see the following on the bottom line:

SSL/TLS connection using TLS1.2 (<some string of letters and numbers>)

When I type in my password on being prompted I see the following in the bottom line of my mutt window:

Authenticating (PLAIN)...

Does this mean that mutt is transmitting my password in plaintext?

Thank you for your help.

Answer 1

The authentication type PLAIN means there is no specific security protocol for the password itself on the IMAP protocol layer.

But the authentication still happens within the TLS1.2 connection, so unless TLS negotiation has accepted a NULL encryption, the whole connection, including the transmission of the password is protected by the TLS1.2.

To identify the actual strength of the TLS1.2 encryption, you would need to find the actual encryption algorithms and key lengths negotiated on the connection. The <some string of letters and numbers> part in the "SSL/TLS connection using TLS 1.2" message contains this information.