Reputation
14,465
Next tag badge:
102/100 score
17/20 answers
Badges
1 36 76
Newest
 Nice Answer
Impact
~288k people reached

Mar
13
comment Why inversion and multiplication operations are costly in elliptic curves?
I'd expect squaring to be counted as a (fraction of) a multiplication. For example, some papers, I read, counted a squaring as 2/3 of a multiplication.
Mar
11
comment Using Counters instead of MAC in CBC mode
CBC decryption propagates an error only to the next block.
Mar
10
comment Fast algorithm for reduction modulo a prime
How big are $a$ and $b$? How big is $|a-b|$? How does the larger algorithm you want to use this in look like?
Mar
9
comment Why haven't we proven many things computationally secure yet?
We haven't even shown that P!=NP.
Mar
8
comment How to calculate min entropy of the output of PRNG?
You don't even need a calculation: It's 0.
Mar
7
revised Decrypting an Affine Cipher with known characters
deleted 9 characters in body; edited tags
Mar
7
revised Affine cipher: calculate the key from a known plaintext/ciphertext pair
edited tags
Mar
7
revised How many oracle calls to break an affine cipher in a chosen plaintext attack?
edited tags
Mar
7
revised Affine cipher and plaintext attacks, how to find the base modulo?
edited tags
Mar
7
revised Prove that the affine cipher over Z26 has perfect secrecy if every key is used with equal probability of 1/312
edited tags
Mar
7
revised Cryptanalysing Affine cipher
edited tags
Mar
7
revised Affine Cipher over an Affine cipher
edited tags
Mar
7
revised Decrypt affine cipher given encryption key
edited tags; edited title
Mar
7
revised Knowing the key, how do I decrypt the affine cipher?
edited tags; edited title
Mar
7
comment Is there any benefit to verifying PKCS#7 padding when using AES CBC and HMAC?
Even if the mode doesn't require padding, you might want to add padding to reduce the information leak through ciphertext length. Once you do, you have the same choice of fully validating the padding, or not.
Mar
7
awarded  Enlightened
Mar
7
comment Decrypt affine cipher given encryption key
$(c-11)\cdot 7^{-1} \pmod {27}$. See also Modular multiplicative inverse
Mar
7
revised How to salt PBKDF2, when generating both an AES key and a HMAC key for Encrypt then MAC?
deleted 14 characters in body
Mar
7
comment How to salt PBKDF2, when generating both an AES key and a HMAC key for Encrypt then MAC?
@d1str0 It's not strictly needed for security, but it ensures that each iteration of the hash has a unique input.
Mar
7
comment How to salt PBKDF2, when generating both an AES key and a HMAC key for Encrypt then MAC?
h1 = HMAC(MasterKey, info | 0x01), h2 = HMAC(MasterKey, h1 | info | 0x02), ... Just look at the HKDF spec I linked above for the details.