Re: [Cfrg] I-D Action:draft-kiyomoto-kcipher2-02.txt

> -----Original Message-----
> From: cfrg-bounces@irtf.org [mailto:cfrg-bounces@irtf.org] On Behalf
Of
> Wook Shin
> Sent: Wednesday, April 13, 2011 4:31 AM
> To: cfrg@irtf.org; Jim Schaad
> Subject: Re: [Cfrg] I-D Action:draft-kiyomoto-kcipher2-02.txt
> 
> Jim,
> 
> That's my mistake. I think I made that mistake while converting
> circular shift operations to the combination of XOR and
> non-circular shit operations.
> 
> The notation in Section 2.1 should be corrected to
> 
>    <<n t     t-bit left shift in an n-bit register
>    >>n t     t-bit right shift in an n-bit register
> 
> and then, the code
> 
>    SubK2((IK[3] <<32 8) XOR (IK[3] >>32 24))
>      XOR (0x01, 0x00, 0x00, 0x00);
> 
> should mean that
> 
>   (1) IK[3] gets left-shifted by 8 bits
>   (2) IK[3] gets right-shifted by 24 bits
>   (3) call SubK2() by giving "(1) XOR (2) XOR 0x01000000"
>       as the input parameter

If that's what you meant, well, that's a really odd notation.
Typically, where someone writes:
    Func(A) op B
They usually mean:
   - Give the value A to function Func, then take the result, and use it
to perform the operation with B.

A more conventional way of writing what you said you meant would be:

    SubK2((IK[3] <<32 8) XOR (IK[3] >>32 24) XOR
                            (0x01, 0x00, 0x00, 0x00));

So, did you mean what you wrote, or did you mean what you said you
meant?

> 
> Best regards,
> 
> Wook
> 
> 
> 
> 
> On Wed, 13 Apr 2011 17:23:10 +0900, Jim Schaad
<ietf@augustcellars.com>
> wrote:
> 
> > You have a notation that is leaving me puzzled.
> >
> > In section 2.1 you say
> >
> >      <<n   Left circular rotation by n bits
> >
> >       >>n   Right circular rotation by n bits
> >
> > Which makes sense.
> >
> > However in section 2.3.2 you use the notation
> >
> >            SubK2((IK[3] <<32 8) XOR (IK[3] >>32 24)) XOR
> >             (0x01, 0x00, 0x00, 0x00);
> >
> > Which is not covered by the above.
> >
> > Additionally I wonder if you mean to use IK[3] in both locations
here
> as
> > (I think)
> >
> > (IK[3] << 8) XOR (IK[3] >> 24) ---> (IK[3] << 8) XOR (IK[3] << (32-
> 24))
> > --> (IK[3] << 8) XOR (IK[3] << 8)
> >
> > jim
> >
> >> -----Original Message-----
> >> From: Wook Shin [mailto:wookshin@kddilabs.jp]
> >> Sent: Tuesday, April 12, 2011 6:39 PM
> >> To: cfrg@irtf.org
> >> Subject: Re: I-D Action:draft-kiyomoto-kcipher2-02.txt
> >>
> >> Hello all,
> >>
> >> I've revised our previous draft that explains the KCipher-2 stream
> >> cipher.
> >> The current version includes some code snippets written in the C
> >> language
> >> syntax, so that it could help implementers get clearer idea of how
> it
> >> works
> >> and help them check their outputs with the test vectors mentioned
in
> the
> >> draft.
> >> The new version of the draft can be found at
> >>    http://www.ietf.org/internet-drafts/draft-kiyomoto-kcipher2-
> 02.txt
> >>
> >> I have attached a naive implementation of KCipher-2 written in C.
> >> Two files, KCipher2.c and KCipher2.h, are in the attached .zip
file,
> >> and no
> >> special option is required to compile and run the program.
> >> The code snippets and the test vector running examples in the draft
> are
> >> from the the attached code.
> >>
> >> Please look at the new version of the draft and the code, and let
me
> >> have
> >> your comments.
> >>
> >> Thank you,
> >>
> >> Wook
> 
> 
> --
> Wook Shin
> Information Security Laboratory,
> KDDI R&D Laboratories, Inc.
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