Subject: Re: relative sizes of URLs and hashes

From: Graham Klyne <[email-masked]>
Date: Sat, 06 Feb 1999 14:15:09 +0000

At 12:58 04/02/99 -0800, Bill Newman wrote:
>Graham wrote
>
>> (a) in the scheme of things, I think a 20-byte hash is quite small --
>> smaller than most URLs.  If a given hash is used more than once in a
>> message, and associated just once with a URL, the result might actually be
>> shorter.   (I am assuming a different approach here to that in some of my
>> recent postings.)
>
>I consider the two to be roughly the same size, because a
>cryptographically secure hash is not compressible, while a URL
>is.

Since you put it that way, I have to agree in principle.

>I don't think that length is a real problem either for
>URL-as-description or hash-as-description schemes. The factor-of-2
>cost of sending both a URL and a hash on every single request would be
>a drawback of any scheme that required that, though.

Yes.

I think I would like to device a scheme that allowed either-or-both, as
long as that did not result in unreasonable additional complexity.

#g

------------
Graham Klyne
([email-masked])