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Concluded WG DKIM Crypto Update (dcrup)

Note: The data for concluded WGs is occasionally incorrect.

WG Name DKIM Crypto Update
Acronym dcrup
Area Applications and Real-Time Area (art)
State Concluded
Charter charter-ietf-dcrup-02 Approved
Document dependencies
Additional resources Issue tracker, Wiki
Personnel Chairs Murray Kucherawy, Rich Salz
Area Director Alexey Melnikov
Tech Advisor Eric Rescorla
Mailing list Address
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Final Charter for Working Group

The DKIM Crypto Update (DCRUP) Working Group is chartered to update
DomainKeys Identified Mail (DKIM, RFC 6376) to handle more modern
cryptographic algorithms and key sizes. DKIM (RFC 6376) signatures
include a tag that identifies the hash algorithm and signing algorithm
used in the signature. The only current algorithm is RSA, with advice
that signing keys should be between 1024 and 2048 bits. While 1024 bit
signatures are common, longer signatures are not because bugs in DNS
provisioning software prevent publishing longer keys as DNS TXT records.

DKIM also currently supports use of SHA1 coupled with RSA. SHA1 has been
formally deprecated due to weakness in numerous contexts.
The community wishes to discourage its continued use
in the DKIM context.

DCRUP will consider four types of changes to DKIM: additional signing
algorithms such as those based on elliptic curves; changes to key
strength advice and requirements; deprecating the use of SHA1;
and new public key forms, such as
putting the public key in the signature and a hash of the key in the
DNS to bypass bugs in DNS provisioning software that prevent publishing
longer keys as DNS TXT records. Changes will be limited to existing
implemented algorithms and key forms. Other changes to DKIM, such as new
message canonicalization schemes, are out of scope. The WG will as far
as possible avoid changes incompatible with deployed DKIM signers and


Date Milestone Associated documents
Dec 2017 Submit WG draft to IESG as Proposed Standard
Oct 2017 Agree what algorithms and key formats to add or deprecate