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Jul
15
comment Ciphertext indistinguishability (IND-CPA) for symmetric cryptography
For the first part, the adversary can submit any two messages. So one (or both) could be repeated.
Jul
15
comment CBC-MAC length extension attack with IV simulation
Let me rephrase, when you say "capture a valid message from target user", is that message encrypted + you have the MAC or is it plaintext + you have the MAC?
Jul
15
comment A question about elliptic curves and finite fields in bilinear pairings
What pairing-free scheme are you looking at?
Jul
15
comment Decryption issue with self-coded AES-128
+1 This should be very helpful to the OP. I fixed one minor mistake in your key schedule.
Jul
15
revised Decryption issue with self-coded AES-128
edited body
Jul
15
comment Decryption issue with self-coded AES-128
If I remember right, implementing AES in Java is tricky as Java does not support unsigned integers. It is possible to do, but you could be suffering from this problem.
Jul
15
comment CBC-MAC length extension attack with IV simulation
So let me get this straight, you are given a single message of the form listed above with some number of transactions and a MAC on that message using CBC-MAC. And you are suppose to come up with a new message which extends the original but adds a transfer to yourself and you are suppose to compute the MAC for that new message. Is that correct? Are you given the plaintext of the message or the ciphertext?
Jul
15
comment A question about elliptic curves and finite fields in bilinear pairings
The mathematical disadvantage for $E(F_p)$ as the target group $G_T$ is that no such construction exists.
Jul
15
answered Galois field step in XEX mode
Jul
15
comment Galois field step in XEX mode
:) My apologies. I hadn't realized you had asked that other question. No, $2^n$ is not equal to $2^n\bmod{2^{128}}$ in $GF(2^{128})$. The only integers (using polynomial representation) in $GF(2^{128})$ are $0$ and $1$.
Jul
14
revised Galois field step in XEX mode
edited title
Jul
14
comment Galois field step in XEX mode
I suggest you take a look at this. In short, it is not $1<<(j\ \%\ 128)$.
Jul
14
comment CBC-MAC length extension attack with IV simulation
Can you add more info on the cipher? Specifically, what is the block size?
Jul
13
comment pairing-based schemes
You should link the paper.
Jul
10
comment How can a Vigenère cipher be broken if the message is short?
The message can be the same size as the key and still have the security of OTP.
Jul
9
comment Is there a practical upper limit for password rehashing?
See also this and this.
Jul
9
comment Is there a practical upper limit for password rehashing?
See this question
Jul
8
comment How is this affine function a pair wise independent permutation?
Can you post the definition of pairwise independent permutation?
Jul
2
awarded  Curious
Jun
27
comment RSA example-calculation: Public Key = Private Key (e = d)
@poncho, thanks! Updated accordingly. I always forget about $\lambda$ when thinking about RSA.