sbp commented on pull request #517: URL: https://github.com/apache/incubator-ponymail/pull/517#issuecomment-673483655
@Humbedooh Collision forgery would require control over entire input messages, unless the source identifier algorithm uses a subset. It also does not enable attacks against the identifiers of existing messages. If a `Received` header was added and is used to compute the identifier, this increases the difficulty of the attack. If an unpredictable header is added by Ponymail and used, this thwarts attacks even against imported archives. But using a 256 bit CSH of the whole message means you get all the security of the hash and no longer have to threat model such collision forgeries. A 256 bit CSH is cheap and currently reliable security. It is reasonable to save this feature for the next generation as long as at least one kind of existing message source identifier has enough collision resistance to make these attacks impractical. Since a range of identifiers are available, their security levels could be noted in the documentation so that implementers can understand the security consequences and decide. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
