-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 In message <[email protected]>, Timo Gerke <[email protected]> writes
> - Signature Expiration (x=) is message-specific. It defines how > long a specific signature on a specific message should be > trusted after transmission (e.g., "this transit proof is valid > for 7 days"). There is no x= tag in DKIM2 What we have is a t= tag that records when the signing was done, and then we encourage Validators to apply a 14 day expiration period ... please read the specification > - Key Expiration (the proposed e=) is infrastructure-specific. > It defines the absolute operational lifecycle of the public > key itself (e.g., "this key belongs to a 90-day rotation > cycle"). in DKIM1 key expiration is done by removing the key from the DNS. That has worked pretty well for 15 years or so and we saw no reason to change that for DKIM2. It is a guiding principle that we will not require anyone with a DKIM1 key to make any changes in order to sign with DKIM2 >The operational risk: If we force operators to abuse x= to mimic >key expiration, a single compromised or misconfigured long-lived >public key allows attackers to forge valid historical messages >indefinitely. "forging historical messages" is all about whether or not the private key is revealed -- and in fact there are some really good reasons for making the private key visible after a while, and some people actually do that. see: <https://blog.cryptographyengineering.com/2020/11/16/ok-google-please- publish-your-dkim-secret-keys/> - -- richard @ highwayman . com "Nothing seems the same Still you never see the change from day to day And no-one notices the customs slip away" -----BEGIN PGP SIGNATURE----- Version: PGPsdk version 1.7.1 iQA/AwUBap1312HfC/FfW545EQKTYwCg9LNy+0m882okdYtdgYSbi/N2b2AAnRzQ +TlHfCeq1jN6jkT9Kd3tkT/9 =7xG4 -----END PGP SIGNATURE----- _______________________________________________ Ietf-dkim mailing list -- [email protected] To unsubscribe send an email to [email protected]
