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lacre:ongoing [2024/04/19 13:02] – Research: avoiding... - multipart messages pfmlacre:ongoing [2024/04/26 17:22] (current) – add: further transformation research pfm
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 ''BytesHeaderParser'' and its string counterpart let us only parse the headers and keep original message body in memory. The drawback is that we can't process multipart messages as sequences of MIME entities, which we need for one of the Lacre's modes of operation. (There are two: PGP/MIME with whole body encrypted and PGP/Inline with each part of multipart message encrypted separately.) We could use ''BytesHeaderParser'' with PGP/MIME only, because a multipart message would be impossible to handle in PGP/Inline mode. ''BytesHeaderParser'' and its string counterpart let us only parse the headers and keep original message body in memory. The drawback is that we can't process multipart messages as sequences of MIME entities, which we need for one of the Lacre's modes of operation. (There are two: PGP/MIME with whole body encrypted and PGP/Inline with each part of multipart message encrypted separately.) We could use ''BytesHeaderParser'' with PGP/MIME only, because a multipart message would be impossible to handle in PGP/Inline mode.
 +
 +===== Research: avoiding message transformation (part 2) =====
 +
 +It turns out that we can avoid //some// of the transformations:
 +
 +  * For messages in cleartext, already encrypted and those processed in PGP/MIME mode we could just take original message content ([[https://aiosmtpd.aio-libs.org/en/latest/concepts.html#Envelope.original_content|Envelope.original_content]]) and process it. Thus we'd avoid using [[https://docs.python.org/3/library/email.contentmanager.html#module-email.contentmanager|email.contentmanager]], which is the component responsible for decoding MIME entities.
 +  * Messages processed in PGP/Inline mode would risk being transformed before encryption.
 +
 +To achieve that, we'd need to adjust the flow and:
 +
 +  - Work with a plain ''Envelope'' initially to identify identities and prepare for encryption.
 +  - We could use header-only parser mentioned above during delivery planning (''lacre.core'', function ''delivery_plan'').
 +  - Finally, if the message is known to be processed in PGP/Inline mode, we could load each MIME entity's body and process it. (Without ContentManager //if possible//.)
 +