On Mon, Apr 21, 2025 at 2:14 PM Alessandro Vesely <[email protected]> wrote:
> While it is relatively easy to detect mime-wrap, footer or similar > transformation, changes in encodings, quotes and comments are difficult or > impossible to guess. Quoted printable can encode each and every character > except alphanumeric with a fixed 76 characters per line. Or it can encode > only non-ASCII characters and insert soft-breaks at the 76th character. Or > something in between. It might make sense to recognize some QP encoding > styles, but then it would be difficult for signers to determine which style > of encoding they are signing. It is much simpler to decode QP and put > base64. > You could canonicalize and then verify that, so: Content-Type: text/plain; charset=us-ascii ...is hashed as: Content-Type: text/plain; charset="us-ascii" ...whether the quotes are there or not. QP strings can be converted to base64 strings, or simply the encodings can be removed, and then the result hashed. And then "relaxed" can take care of space additions and wrapping. But you can only go so far with such heuristics. At some point I think you'd be going way too far to guess at upstream changes that may or may not have happened. I don't know what a QP "style" is; there's only one encoding I know of. -MSK
_______________________________________________ Ietf-dkim mailing list -- [email protected] To unsubscribe send an email to [email protected]
