Re: [openpgp] Fingerprints and their collisions resistance

[Andrey Jivsov <[e-mail]>]

On 01/03/2013 10:25 PM, ianG wrote:
...
> Hence my earlier question - has anyone allocated the OpenPGP numbers for
> Keccak as yet?  The reason I asked is because I stumbled on the code
> last week and thought what a fine idea it would be to at least prepare
> the way....  Strawman?
>
>    SHA3-224         4        12
>    SHA3-256         5        13
>    SHA3-384         6        14
>    SHA3-512         7        15
>
> Strawman?  I'm not sure why there is a gap 4-7 in rfc4880.  Are there
> any spots already allocated?
>

One point I wanted bring up here based on the draft that I wrote last 
year is that let's think for a moment about the usefulness of the SHA3-224.

I would like to see an argument for it. Algorithms like DSA/ECDSA are 
capable to deal with hash truncation or padding. RSA mod has sufficient 
space to always use SHA3-512.

The question is especially relevant if you familiarize yourself with the 
Keccak. Keccak is basically a single hash algorithm which output is 
truncated to 256, 384, 512, etc bits. The only difference between 
SHA3-256 and SHA3-512, for example, is one integer used in the internal 
loop.

You can always go with stronger security. Who are those people who would 
not be OK with SHA3-256 but are happy with SHA3-224 ? Why can't they use 
shorter public keys (to solve space concerns?) ?