On Wed, 15 Jan 2014 22:41:43 +0100
[email protected] (Niels Möller) wrote:

> Stefan Bühler <[email protected]> writes:
> 
> > What about:
> >
> >   chacha20_crypt (20 rounds)
> >   chacha12_crypt (12 rounds)
> >   chacha_set_key128 (128 key bits)
> >   chacha_set_key256 (256 key bits)
> >   salsa20_set_key128 (128 key bits)
> >   salsa20_set_key256 (256 key bits)
> 
> My gut feeling is that think putting the number of bits last is too
> inconsistent with aes128_set_*_key and similar functions.

Imho that is the point; aes128_* are the functions of the AES128
variant, which "accidentally" uses a 128-bit key; the variant could have
a different name (aes10 for 10 cycles), and would still take a 128-bit
key.
chacha_set_key128 is a function that works for all Chacha variants, and
always takes a 128-bit key.

(I wouldn't split the key set functions for Salsa20 and Chacha in the
first place - you didn't say why you wanted to split them, but you
probably have your reasons)

> >> Opinions?
> >
> > Imho moving Salsa20/R functions to the ChachaR naming would work
> > too :)
> 
> That's one option. What do others think? (We could keep aliases for
> backwards compatibility, whenever practical).
> 
> > And don't forget XSalsa20/r (using HSalsa20/r and an additional
> > 128-bit nonce, defined only for 256-bit keys afaik, but
> > theoretically should work with 128-bit keys too)...
> > xsalsa20r12_set_key256? :D
> 
> I'm not familier with those variants. But I think they should have a
> different name space (e.g., xsalsa*), so at least they shouldn't
> collide with plain salsa20 functions.

I just wanted to point out how riddiculous it looks when too many
numbers are in a function name.

XSalsa basically replaces the Salsa20 key in set_iv with one derived
(with HSalsa, selected output from the doublerounds) from the original
key and additional nonce data as temporary iv and counter.
So you would call "xsalsa20_set_iv" or "xsalsa20r12_set_iv"
instead of "salsa20_set_iv", it wouldn't actually need a different
set_key.

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