Subject: Re: [Ietf-krb-wg] I-D Action:draft-lha-des-die-die-die-00.txt

From: Love Hörnquist Åstrand <[email-masked]>
Date: Sun, 02 Aug 2009 11:59:13 +0200

31 jul 2009 kl. 18:57 skrev Jeffrey Hutzelman:

> --On Friday, July 31, 2009 05:12:36 PM +0200 Simon Josefsson <[email-masked] 
> > wrote:
>
>> The document only deprecates the encryption types.  What about the
>> checksum types?  RFC 3961 defines several historicy checksum types:
>>
>>   CRC32                            1               4           6.1.3
>>   rsa-md4                          2              16           6.1.2
>>   rsa-md4-des                      3              24           6.2.5
>>   des-mac                          4              16           6.2.7
>>   des-mac-k                        5               8           6.2.8
>>   rsa-md4-des-k                    6              16           6.2.6
>>   rsa-md5                          7              16           6.1.1
>>   rsa-md5-des                      8              24           6.2.4

Added text to describe that these type are deprecated too, thanks for  
catching this.

> While not strictly within the scope of this document, I'd support  
> moving RSA-MD4, RSA-MD4-DES, DES-MAC, and DES-MAC-K to historic,  
> along with DES-CBC-MD4, even if we were _not_ killing DES  
> altogether.  In fact, in retrospect I'm moderately surprised we  
> didn't do so in RFC4120.
>
> RSA-MD5 is a bit trickier, as I seem to recall there are  
> implementations which actually use this unkeyed cksumtype in places  
> where an authenticated checksum is not strictly required.  What I  
> don't know is whether any of these continue this behavior when DES3- 
> CBC-SHA1 or one of the AES enctypes is used.

I've only seen RSA-MD5 with ARCFOUR-HMAC-MD5 (in addition to the DES  
enctypes).

> I don't recall whether CRC32 is actually in use for anything or not.

Still going to say its deprecated and should not be implemented.

> If it's going to change the status of enctypes defined in RFC3961,  
> then yes, it needs to Update that document.  And you're right; if  
> we're going to move DES-CBC-MD5 to historic we need to update the  
> mandatory-to-implement enctypes in Kerberos.
>
> BTW, what you quoted also seems to contain an error - there is no  
> "DES-MD5" cksumtype.  Unfortunately, I can't remmber whether the one  
> we intended to mandate was RSA-MD5 (unkeyed) or RDS-MD5-DES.

I wrote the the draft that RSA-MD5 is deprecated when used with the  
DES types and was only for legacy system that didn't support newer  
checksums.

I've resubmitted the draft with update text.

Thanks for the feedback.

Love

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