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seen Sep 13 at 20:26

Sep
5
answered Hill Cipher question
Aug
6
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Aug
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Jun
25
comment Is it a good idea to use Lagrange/Newtonian interpolation for encryption?
Your description (and purpose of the scheme) isn't clear, I am afraid. Could you give a tiny concrete illustrative example with its usage in practice?
Jun
21
comment How can I find the multiplicative inverse in the first transformation of the SubBytes() transformation in AES?
If a computation is done in a finite field, there is IMHO barely a possibility to appropriately re-formulate that in terms of common arithmetic operations (for the purpose of rendering it easier to comprehend). You would have to either learn the basics of finite fields or take the results of others for granted, I am afriad.
Apr
2
comment Is substitution with random prefix codes secure?
@rath: I have deleted (2) corresponding to your suggestion.
Apr
1
revised Is substitution with random prefix codes secure?
deleted 300 characters in body
Mar
30
comment Is substitution with random prefix codes secure?
I have duly correspondingly formulated my new question with the best care I could manage to do to limit its scope to the least minimum and posted it under the title "Any good means to enhance the security of encryption processing with random prefix codes".
Mar
29
comment Is substitution with random prefix codes secure?
I understand you mean that one should limit the scope of a question to the least minimum possible. So I'll have to ask a new question in the present context. Thank you very much for the guidance.
Mar
28
comment Is substitution with random prefix codes secure?
But IMHO in crypto one rarely uses one single algorithm (in the narrow sense) but a combination of confusion and diffusion in the terms of Shannon. So if one appropriately combine prefix-coding with e.g. certain transpositions, would that be a good defense against known/chosen text attacks? (In fact I have attempted to do such a combination in a humble scheme of mine recently (s13.zetaboards.com/Crypto/topic/7164646/1). Actually, it was because I was not very sure whether prefix-coding is "self-sufficient" that I did the original posting in order to learn more about its real strength.)
Mar
28
comment Is substitution with random prefix codes secure?
@figlesquidge: Done. Thank you.
Mar
28
revised Is substitution with random prefix codes secure?
added 682 characters in body
Mar
28
comment Is substitution with random prefix codes secure?
Oh, I should have replaced "claim" with "claim according to my interpretation", since I am not 100% sure of the correctness of my interpretation (as I said, my understanding of the article is only partial). If the real claim is not correct, then the other phrase of mine would make sense IMHO.
Mar
26
comment Encryption of numeric value using playfair
If the matrix doesn't have 5, then you simply cannot process that character with that matrix. Perhaps you were expected to think of the use of a larger matrix than the one shown in the lessons.
Mar
26
asked Is substitution with random prefix codes secure?
Mar
14
comment How to best mix two arbitrary/random n-bit words?
The specific application that interests me currently would certainly be deemed too mundane from a theoretical point of view. In a certain encryption processing I am considering there are two n-bit words, x and y, one on the plaintext side and one on the ciphertext side (but neither is directly plaintext or ciphertext). I like to combine them into z and sum the z's of all preceding blocks into a value s and use that to chain the blocks. It's my thinking that, if z is "somehow" optimal in capturing the randomness of x any y, then the chaining would also be fine. Would that satisfy your query?
Mar
14
comment How to best mix two arbitrary/random n-bit words?
What I would prefer to have is not to use, if possible, a rather complex computation like a crypto-secure hash function but some more simple computations in practice, of the genre of xor you mentioned. For it is not extremely high crypto security that is demanded in the cases I have in mind but, roughly speaking, certain comparatively good security that could be obtained with some not too expensive computing expenses.
Mar
12
comment How to best mix two arbitrary/random n-bit words?
I am merely using an example to answer your question of defining "optimally". That is, the notion of "better" exists in the present context. My problem as such is evidently indepent of what one could best do with that specific potential application.
Mar
11
comment How to best mix two arbitrary/random n-bit words?
Let's consider the following case: Suppose one encrypts 2 natural language texts (there are estimates of some 1 bit pro character, if I don't err) with a certain block cipher to obtain 2 sequences of blocks. Now one desires to combine these sequences into one sequence with the goal that the resulting sequnce is hopefully better in the sense of entropy. (If I don't err, measuring entropy is difficult, but it seems nonetheless not incorrect to expect/demand that the resulting sequence should have higher entropy.)
Mar
11
comment How to best mix two arbitrary/random n-bit words?
ok. Let's say one has in some crypto processing obtained x and y and then need to combine them into z for going further, how should one do that optimally?