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Jul
19
answered Can a EC private key be derived from a public key?
Jul
18
answered How to calculate complexity of ElGamal cryptosystem?
Jul
16
reviewed Close Does having a known plaintext prefix weaken AES256?
Jul
16
reviewed Leave Open Does bad IV generation weaken CBC?
Jul
16
reviewed Leave Open Can I crack an AES string if I have all these parameters?
Jul
16
comment Using GMAC for Authentication without encrypting the message
The "additional associated data"; that's the part of the data which is used to compute the tag, but is not encrypted.
Jul
16
comment Using GMAC for Authentication without encrypting the message
GMAC is just GCM with a empty "message to be encrypted"
Jul
16
comment Is there a technique to confirm that a given large integer value is a product of two primes?
@ColeJohnson: the "precomputed primorial" for a prime of that size is approximately $2^{1400}$ bits long. Yes, in addition to computing the gcd, just storing it would be highly nontrivial -- that is part of why I was skeptical of this approach...
Jul
15
awarded  Pundit
Jul
15
revised Decrypting an encrypted text out of order
edited tags
Jul
15
comment Attack on DSA modification with bad hash function
"Apparantly, I'll have to calculate the private key $x$" -- nope, recovering the private key is not required.
Jul
15
comment Ciphertext indistinguishability (IND-CPA) for symmetric cryptography
"This is true for any deterministic symmetric encryption" -- you have just shown that an IND-CPA encryption method must be nondeterministic,
Jul
15
reviewed No Action Needed Ciphertext indistinguishability (IND-CPA) for symmetric cryptography
Jul
15
comment How does one calculate the scalar multiplication on elliptic curves?
Ummm, "double and add" and "square and multiply" are two ways to say the same time. Also, what's a "mandelbrot sequence" or a "divide and add" (at least, in terms of working with a group operation?).
Jul
14
reviewed Close Could I use an hashing function for Symmetric encryption?
Jul
14
reviewed No Action Needed mixing two asymmetrical random number generator streams
Jul
12
answered How does recovering the public key from an ECDSA signature work?
Jul
12
comment Effective security of block cipher – equal the key size, or half the key size?
I don't have the book, but might Viega and Messier have actually said "the effective strength ... is actually half the block size"; which might be one way of expressing that if you have a block cipher with a block size of $n$ bits, you generally don't want to use it for more than $2^{n/2}$ blocks ???
Jul
12
answered Is jacobian to projective conversion unique?
Jul
10
comment Calculating IHVs from known message and hash output
@DmitryYanushkevich: no, there is not. In fact, the existence of a method that could solve it in, say, 2^150 steps, could be used to find preimages in 2^156 steps (for SHA-1).