RFC 3871           Operational Security Requirements      September 2004

      Note that for *new protocols* [RFC3631]  says the following:

      "Simple keyed hashes based on MD5 [RFC1321], such as that used in

      the BGP session security mechanism [RFC2385], are especially to be

      avoided in new protocols, given the hints of weakness in MD5."

      While use of such hashes in deployed products and protocols is

      preferable to a complete lack of integrity and authentication

      checks, this document concurs with the recommendation that new

      products and protocols strongly consider alternatives.

   Warnings.

      This list is not exhaustive.  Other strong, well reviewed

      algorithms may meet the requirement.  The dynamic nature of the

      field means that what is good enough today may not be in the

      future.

      Strength is relative.  Long keys and strong algorithms are

      intended to increase the work factor required to compromise the

      security of the data protected.  Over time, as processing power

      increases, the security provided by a given algorithm and key

      length will degrade.  The definition of "Strong" must be

      constantly reevaluated.

      There may be legal issues governing the use of cryptography and

      the strength of cryptography used.

      This document explicitly does not attempt to make any

      authoritative statement about what key lengths constitute "strong"

      cryptography.  See  [RFC3562] and [RFC3766] for help in

      determining appropriate key lengths.  Also see [Schneier] chapter

      7 for a discussion of key lengths.

2.2.3.  Use Protocols Subject To Open Review For Management

   Requirement.

      If cryptography is used to provide secure management channels,

      then its use MUST be supported in protocols that are subject to

      "open review" as defined in Section 1.8.  These SHOULD be used by

      default.  The device MAY optionally support the use of

      cryptography in protocols that are not open to review.

Jones                        Informational                     [Page 14]