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Dec
22
comment Keeping IV secret for AES CFB mode
...unless they never reuse the key for two different messages; in that specific case (and only in that case) using a constant IV is safe.
Dec
22
reviewed Satisfactory Why is sharing the seed and using SecureRandom “deterministically” so bad?
Dec
22
comment Two-dimensional S-Box
If $S'$ and $S''$ are the same S-box, why do you use two different symbols to represent them?
Dec
22
comment Two-dimensional S-Box
I'm not sure I understand what you're asking. If $S_1$ and $S_2$ are $n$-bit-to-$n$-bit S-boxes, then the function $S_{12}$ defined as $S_{12}(x) = S_2(S_1(x))$ can also be represented as an $n$-bit-to-$n$-bit S-box, so combining S-boxes like that generally doesn't gain you anything.
Dec
21
answered hill cipher encryption way 1x3 plaintext matrix
Dec
21
revised ECB weakness and its exploitation
edited tags
Dec
21
comment ECB weakness and its exploitation
You should be able to find out the length of A, at least rounded down to a multiple of 16 bytes, by changing your message and seeing which ciphertext block is the first one that changes. Can you then figure out how to get the exact length of A in bytes? (Hint: What happens to the ciphertext if A is, say, 15 bytes long, and you change the first byte of your data? What if you change the second byte instead?)
Dec
21
answered ECB weakness and its exploitation
Dec
17
comment Authentication mechanism for low memory, low computing power device
If you can't even do AES at all, I'm not sure how you think you're going to implement any kind of zero-knowledge proof. There's very little practical crypto you can do with devices that limited. (Then again, it's also possible that you're just underestimating the performance of your processors; even many smart cards can do AES nowadays.)
Dec
17
comment Authentication mechanism for low memory, low computing power device
You might want to add some more details to your question. For instance, who/what do you want to authenticate to whom, what kind of keys/passwords/tokens do they share, what kind of processor are you talking about ("low" can be relative), and what kind of attack scenarios are you expecting?
Dec
17
awarded  Autobiographer
Dec
17
revised What does pseudo pre-image of a hash function mean?
edited tags
Dec
16
answered What is the difference between a one-shot MPC protocol and a unbounded invocation of multiple MPC protocols?
Dec
16
revised What is the difference between a one-shot MPC protocol and a unbounded invocation of multiple MPC protocols?
copyedit, TeX formatting
Dec
16
revised Decryption or attacking DES encrypted file
edited tags
Dec
16
revised DES — Can I recover the key when I have both ciphertext and the plaintext?
edited tags
Dec
15
reviewed No Action Needed Sample RSA-style signature confusion
Dec
15
revised Sample RSA-style signature confusion
correct 5043 -> 5023 per Wolfram Alpha; misc. TeX tweaks
Dec
14
reviewed Approve
Dec
14
reviewed Approve