The original post: /r/usenet by /u/Soga_Nakamaro on 2024-12-27 19:49:32.

I’m trying to understand Usenet specifications and would like to generate messages with Cancel-Locks as specified in RFC 8315. To do this, I would need a Usenet client that automatically posts messages with the calculated Cancel-Lock field, or I would need access to the Message-ID of proto-articles before posting in order to calculate it manually.

As far as I know, Thunderbird doesn’t support either of these features. However, I’ve seen messages in text newsgroups with a User-Agent of Thunderbird that include valid Cancel-Locks, like this:

Message-Id: <vkaic4$t8n2$1@dont-email.me>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0
Cancel-Lock: sha1:GGmAddL3shnovaCu7R53m3R6oPU=

How do people manage to do this? I’m starting to think they might generate a random SHA-1 cancel key, hash it again with SHA-1 to create the cancel-lock, and then add this cancel-lock as a custom header in Thunderbird. But that doesn’t seem quite right, does it?

Does anyone know?