Subject: [AAA-WG]: Issues 262 & 263: A Diameter node must use its own TLS certificate Issue 263: Mandate required TLS cipher suites

From: <[email-masked]>
Date: Tue, 26 Feb 2002 22:45:53 +0200

Hi all,

These seem like reasonable requests, however I'd like some feedback
from the security experts on the list before I make the changes.

John

Issue 262: A Diameter node must use its own TLS certificate 
Submitter name: Don Zick 
Submitter email address: 
Date first submitted: 08-Jan-02 
Reference: 
Document: Base 08 
Comment type: Technical 
Priority: 1 
Section: 2.2 
Rationale/Explanation of issue: 
The Diameter base draft does not address how to ensure that a Diameter 
node is using its own TLS certificate. It is important to ensure that 
a Diameter node is using its own TLS certificate so that if a single 
Diameter node becomes compromised, it won't break security for all of 
the other Diameter nodes. 

It is a common practice with TLS to put a node's identity into the 
certificate's subjectAltName dNSName field. The Diameter CMS Security 
Application takes this approach. Below is a section from the Diameter 
CMS Security Application draft 3: 

>3.2 Certificate Requirements 
> 
> Certificates used for the purposes of Diameter MUST conform to the 
> PKIX profile [4], and MUST also include a Diameter node's FQDN, which 
> is typically added in the Origin-Host AVP [1], as one of the values 
> of the subjectAltName extension of the Certificate. The FQDN is to 
> be encoded as a dNSName within the subjectAltName. > 
> For Diameter nodes (capable of acting as recipients for 
> confidentiality), the FQDN MUST be of the form 
> "Diameter-.". Other Diameter nodes MAY use this naming 
> scheme. Note that this naming constraint is for PKI purposes only, 
> and in no way restricts a Diameter's host name. 

Requested change: 

Make Diameter TLS have the same dNSName field requirements as the 
Diameter CMS Security Application. 

Issue 263: Mandate required TLS cipher suites 
Submitter name: Don Zick 
Submitter email address: 
Date first submitted: 08-Jan-02 
Reference: 
Document: Base 08 
Comment type: Technical 
Priority: S 
Section: 2.2 
Rationale/Explanation of issue: 
Diameter implementations should not be required to support all TLS 
cipher suites listed in RFC 2246. Not all cipher suites are supported 
by available TLS tool kits and one cipher suite contains the proprietary 
IDEA encryption algorithm that you have to get permission to use. 
Therefore, to ensure inter operability, it is necessary to specify which 
cipher suites must be supported. 

Requested change: 

Add: 

Diameter nodes MUST be able to negotiate the following TLS cipher 
suites: 
TLS_RSA_WITH_RC4_128_MD5 
TLS_RSA_WITH_RC4_128_SHA 
TLS_RSA_WITH_3DES_EDE_CBC_SHA 
Diameter nodes MAY negotiate other TLS cipher suites.