[Fwd: Re: [ietf-dkim] canonicalized null body and dkim]

[Charles Lindsey]

On Sat, 23 Dec 2006 00:39:07 -0000, Hector Santos <hsantos at santronics.com>  
wrote:

> Charles Lindsey wrote:
>> On Thu, 21 Dec 2006 17:55:41 -0000, Hector Santos
>
>>> if l=2,  that means two <CRLF> were hashed.
>>  But that case cannot arise with the text proposed.
>
> But what if it is l=2, what if that is what the VERIFY sees?  It means  
> whether truly BYTES exist or not, these two hashable bytes must be  
> <CR><LF>.

No, if what was hashed has zero bytes in it, then you MUST NOT say 'l-2'.
>
>>> if l= missing, that means at minimum two <CRLF> were hashed.
>>  No, it means whatever the canonicalization produced would be hashed,  
>> which would be <empty> in this case.
>
> Ok, again, we are talking VERIFICATION here. If no l= tag is specified  
> as part of the DKIM-Signature: header, the specs says the "entire" body  
> is hashed. Therefore, according to what I am reading, if the body is  
> indeed DKIM-NULL (empty after any <CRLF> trimming) then 2 bytes <CRLF>  
> will be hashed.

If the body is indeed NULL/empty/whatever, then WHY do people want to do  
anything to it, like adding a <CRLF> out of thin air? The text I have  
proposed says to leave it empty in that case.
>
> Are you saying there SHOULD be no hashing and therefore no b= tag?

No, you hash <empty> and the result of that goes into the b= tag.

Apparently, the result of hashing an empty file with sha-256 is
    47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU
so that would go in the b= tag.

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
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