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Where can I view the selected connection encryption algorithms/ciphers when using SSL/TLS for IMAP and SMTP?

JustCurious
JustCurious
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When using Firefox I can view the session encryption algorithms by clicking on the (hopefully) green padlock, click the "More Information" button, select the "Security" icon and then view the protocol, key exchange, encryption, mode and integrity algorithms selected for the session in the "Technical Details" section.

In Thunderbird I have IMAP and SMTP configured with SSL/TLS for the connection, but I can not find information about the encryption algorithms selected for the sessions anywhere. How can I view this information?

When using Firefox I can view the session encryption algorithms by clicking on the (hopefully) green padlock, click the "More Information" button, select the "Security" icon and then view the protocol, key exchange, encryption, mode and integrity algorithms selected for the session in the "Technical Details" section. In Thunderbird I have IMAP and SMTP configured with SSL/TLS for the connection, but I can not find information about the encryption algorithms selected for the sessions anywhere. How can I view this information?

All Replies (1)

JustCurious
JustCurious Question owner
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This is what I have found:

To see the ciphers available at the server:

To see the ciphers configured in Thunderbird enter a client test site as Thunderbird Start Page (Customizing the Start Page ). Use say one of:

To find the cipher selected for a particular session:

  1. Download and install Wireshark
  2. Start Wireshark with capture filter: port 993 and host imap.gmail.com
  3. Enter display filter: ssl.handshake.type == 1 or ssl.handshake.type == 2
  4. Start Thunderbird and fetch mail.

The cipher suites offered by Thunderbird are listed in IANA notation in the Client Hello message and the selected session cipher in Server Hello (look in Wireshark).

Replace 993 and imap.gmail.com with the tcp port and server you want to check (View Settings for this account / Server Settings / Server Name: and Port.)

Unfortunately the information does not seem to be available in Thunderbird itself yet. An account padlock hover message would be fine.

Modified by JustCurious