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

"Wook Shin" <wookshin@kddilabs.jp> Wed, 13 April 2011 08:31 UTC

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To: cfrg@irtf.org, "Jim Schaad" <ietf@augustcellars.com>
References: <20110413010001.17531.11616.idtracker@ietfc.amsl.com> <op.vtur72zepzjggh@ohpato-t61.sec.kddilabs.jp> <00a201cbf9b4$06bc8a00$14359e00$@augustcellars.com>
Date: Wed, 13 Apr 2011 17:30:47 +0900
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From: "Wook Shin" <wookshin@kddilabs.jp>
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Subject: Re: [Cfrg] I-D Action:draft-kiyomoto-kcipher2-02.txt
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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

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.