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Recognized Transformations of Messages Bearing DomainKeys Identified Mail (DKIM) Signatures

Document Type Expired Internet-Draft (individual)
Expired & archived
Author Murray Kucherawy
Last updated 2021-01-06 (Latest revision 2020-07-05)
RFC stream (None)
Intended RFC status (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


DomainKeys Identified Mail (DKIM) introduced a mechanism whereby a mail operator can affix a signature to a message that validates at the level of the signer's domain name. It specified two possible ways of converting the message body to a canonical form, one intolerant of changes and the other tolerant of simple changes to whitespace within the message body. The provided canonicalization schemes do not tolerate changes in a message such as conversion between transfer encodings or addition of new message content. It is useful to have these capabilities to allow for transport through gateways, and also for transport through handlers (such as mailing list services) that might add content that would invalidate a signature generated using the existing canonicalization schemes. This document presents a mechanism for declaring that a message underwent any of a handful of well-defined transformations prior to being re-signed by a mediator, so that a verifier might rewind such modification(s) and thereby confirm that the original signature still verifies against the original content.


Murray Kucherawy

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)