Why is it unsafe to use the DNSSEC algorithm RSA/MD5? In practical terms, how is DNSSEC weakened by the use of an algorithm such as MD5, which has a known weakness of collisions?
RFC 6944 states, under chapter 2.3 DNSSEC Implementation Status Table: "Implementation status: Must Not Implement" about RSA/MD5.
Furthermore the RFC states:
4. Security Considerations
This document lists, and in some cases assigns, the implementation status of cryptographic algorithms used with DNSSEC. It is not meant to be a discussion on algorithm superiority. No new security considerations are raised in this document, though prior description of algorithms as NOT RECOMMENDED (see [RFC4034]) has been recast as Must Not Implement.