I'm finishing a new blog setup in Multisite (subdomains config and with domain mapping) and found that the Comments module was not working and dumping a
Invalid security token error.
There's another thread here in the forums about this issue, I disabled all plugins that could cause a problem (Bad-Behavior, Antispam Bee), but the error persisted.
I checked the values of
$post_array['sig'] in the function
pre_comment_on_post (/jetpack/modules/comments/comments.php), and they are indeed different.
Following the lead, I arrived in the function
get_option() in the main file (/jetpack/jetpack.php).
If I change both occurrences of
get_site_option, the comments work...