IPFYI
RFC 8301 Best Current Practice

Cryptographic Algorithm and Key Usage Update to DomainKeys Identified Mail (DKIM)

S. Kitterman · 2018-01

Abstract

The cryptographic algorithm and key size requirements included when DKIM was designed in 2006 are increasingly weak as hardware and cryptanalytic advances continue. This document updates DKIM requirements to those minimally suitable for near-term future use and removes DKIM's requirement for SHA-1 support.

Why This RFC Matters

RFC 8301 addressed the aging cryptographic underpinnings of DKIM by mandating RSA key sizes of at least 1024 bits (with 2048 bits strongly recommended) and removing the SHA-1 algorithm from the required algorithm set, reflecting that SHA-1 collision attacks had become feasible. For email operators this meant rotating DKIM signing keys to stronger parameters, a change that major email providers and ESPs implemented in 2018. The Best Current Practice status signals that this is an operational requirement rather than just a theoretical recommendation, directly affecting email deliverability for domains using under-specified key configurations.

관련 프로토콜

SMTP DKIM SPF

관련 용어

authentication encryption certificate

Security에서 더 보기

RFC 2404 The Use of HMAC-SHA-1-96 within ESP and AH RFC 3602 The AES-CBC Cipher Algorithm and Its Use with IPsec RFC 4253 The Secure Shell (SSH) Transport Layer Protocol RFC 4254 The Secure Shell (SSH) Connection Protocol RFC 4301 Security Architecture for the Internet Protocol RFC 5246 The Transport Layer Security (TLS) Protocol Version 1.2 RFC 5280 Internet X.509 Public Key Infrastructure Certificate and CRL Profile RFC 6125 Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)