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Feb
1
answered Generation of a cyclic group of prime order
Jan
31
answered Do any stream ciphers with aperiodic keystreams exist?
Jan
31
answered Proof that $gcd(e, \lambda(N)) = 1 \hspace{1mm} \Longleftrightarrow \hspace{1mm} gcd(e, \varphi(N)) = 1$
Jan
31
revised One time pad probability
added 208 characters in body
Jan
31
answered One time pad probability
Jan
30
comment Proving the complement property of DES?
Note: the question that I marked this as a duplicate isn't an exact duplicate - however, the answer to that question answers this as well.
Jan
30
comment How hard is it to find plaintexts whose hashes satisfy $h(a)\oplus h(b)=h(c)$?
@RobertNACIRI: yes; the obvious approach is to pick an arbitrary $a$, and then use a birthday attack to find a $b, c$.
Jan
30
comment How hard is it to find plaintexts whose hashes satisfy $h(a)\oplus h(b)=h(c)$?
And it's easy to show that it's at most $O(2^{n/2})$ -- how can we establish where in that range the answer is?
Jan
30
answered Is there a reference that prove that the AES Key Schedule generate random looking round keys?
Jan
30
reviewed No Action Needed How secure is it to use password as AES key?
Jan
30
reviewed Close Achieving 32-bit verification code with 16-bit CRC?
Jan
30
reviewed Close How are calculated numbers in AES S-box?
Jan
30
reviewed Leave Open 1 Billion Bit Encryption?
Jan
29
comment In RSA, why does $p$ have to be bigger than $q$ where $n=p \times q$?
The question was based on behavior seen within OpenSSL; the OpenSSL bignum library handles negative numbers properly, and hence this answer is irrelevant in the context of the original question.
Jan
29
reviewed No Action Needed How do I communicate the value of the initialization vector to the end user? Should it be part of the encrypted message?
Jan
28
reviewed Reviewed Point decompression on an elliptic curve
Jan
28
comment Point decompression on an elliptic curve
Shanks-Tonelli is the general answer for prime curves; however most elliptic curves have $p \equiv 3 mod 4$, and in this case, the problem can be simplified: to compute the square root of $n$, you just compute $n^{(p+1)/4}$ (and check that that value squared gives you $n$; this last bit catches values of $n$ that don't have a square root)
Jan
28
reviewed Close Is there a strong cryptographic reason for GCM's 2^39 - 256 bit limit?
Jan
28
reviewed No Action Needed Why isn't CTR mode (counter mode) used more often?
Jan
27
comment Proving that an encryption scheme is susceptible to certain attacks
@user21547: if $e_1 - e_2 = a(m_1 - m_2) + (k_1-k_2)p$ and $e_2 - e_3 = a(m_2 - m_3) + (k_2-k_3)p$, what is $(e_1-e_2)(m_2-m_3) - (e_2-e_3)(m_1-m_2)$?