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seen Oct 11 at 0:30

Feb
1
awarded  Informed
Nov
24
awarded  Custodian
Nov
24
reviewed Approve suggested edit on OMAC : Padding on empty string
Nov
22
awarded  Critic
Nov
22
accepted OMAC : Padding on empty string
Nov
21
asked OMAC : Padding on empty string
Nov
4
accepted Serpent cipher : Osvik S-Boxes confusion and test vectors
Nov
4
comment Serpent cipher : Osvik S-Boxes confusion and test vectors
Now, I understand why this is different and that makes sense with your explanation. Osvik should write another paper to explain his changes for people who want to understand what's happening, not just copying the code :). Thanks for your explanations (+1). I'm no more confused now.
Nov
1
comment Serpent cipher : Osvik S-Boxes confusion and test vectors
I just tested the values and I got the same results as you. My implementation is done in LittleEndian as it is mentioned in the paper. So am I right ? Sorry, but now, I'm still more confused... which one is right ?
Nov
1
asked Serpent cipher : Osvik S-Boxes confusion and test vectors
Oct
20
accepted Serpent block cipher : S0 to S7 functions unclear
Oct
20
comment Serpent block cipher : S0 to S7 functions unclear
That's what I needed, thanks for your answers (+1). I also found this paper from Osvik which help me to understand the Osvik construction S-Boxes.
Oct
18
comment Serpent block cipher : S0 to S7 functions unclear
I took a look to serpent.java from your link and it's the same code as the one I have in Java. It still use code like RND00 function I mentioned in my post.
Oct
18
asked Serpent block cipher : S0 to S7 functions unclear
Oct
10
accepted Specification of the scream stream cipher is unclear
Oct
9
comment Specification of the scream stream cipher is unclear
I successfully implement the Scream cipher with the tests given at the end of the paper. In question 2, matrices are fixed [[1,2],[2,1]] and [[1,3],[1,3]]. So, 2 and 3 are NOT replaced by x. The multiplication is on GF(256) with the polynomial specified at page 4. Thus, you have to do something like this : GF256_Multiply(2, S1[x], 0x1C3) where 2 = M1(0,1) = M1(1,0) for example. Now, I understand why they call T0 and T1 lookup tables. These are fixed tables which imply M1 and M2 are fixed too. Hope my explanations are clears enough.
Oct
9
awarded  Scholar
Oct
9
awarded  Supporter
Oct
9
comment Specification of the scream stream cipher is unclear
If I understood well your explanations, the x in the matrices is the same as the input parameter x of the function F. Then, in the multiplication M1(0,1) by S1[xi], the x in matrices are replaced by xi for i=0,...,15 for example. So the multiplication would be normal by replacing x by the correct xi. By the way, these multiplications are necessary to make tables T0 and T1 described in section 3. Sorry if I misunderstood you, but I just want to make sure my logic is right. Thank you very much.
Oct
9
comment Specification of the scream stream cipher is unclear
Thanks for the answer. Question 1 and 3 sound good to me. For the second question, the authors mentioned the polynomial at page 4 of the paper. Then, the elements of the 2 matrices belong to GF(256) with the polynomial given. But, S[x] is multiply with 1, x or x+1. Following my logic, should we prefer the multiplication of GF(256) or is it fair to just change x by 2 and x+1 by 3 and multiply normally ? This is confusing me. I'd appreciate clarifications on that point if possible.