Reputation
3,872
Top tag
Next privilege 4,000 Rep.
Access 'trusted user' tools
Badges
2 16
Impact
~49k people reached

Apr
17
comment Multiple encryptions of different data with same key all end with same pattern
I have no idea what you are trying to ask
Apr
10
comment Discover key with known-plaintext attack
I would also guess it is a 64-bit ECB cipher, which is then encoded to text readable format through something like B64
Apr
9
comment KDFs for symmetric encryption master key & serial number
Personally, I would use HMAC-SHA512 and truncate to the required key size
Apr
8
comment Salsa20-GCM composition secure?
@ArekBulski that means a cipher with a key strength at least as good as the security guarantee of the authentication, which is 128-bits. ChaCha with Poly1305 has been added as an RFC for the next version of TLS, and is already available in Google Chrome
Apr
7
answered Salsa20-GCM composition secure?
Apr
7
comment AES GCM calculator
test the examples from the official document: csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/gcm/…
Apr
7
answered Affine transformation in AES: Matrix representation
Apr
7
comment Affine transformation in AES: Matrix representation
I am answering now, give me 20 mins
Apr
6
comment Affine transformation in AES: Matrix representation
C.4 shows the polynomial representation of the ENTIRE s-box, not of the affine transformation
Apr
3
comment Are there any valid, and person readable, checksums possible?
actually I think he is looking to see if there is a plaintext that would create a hash like 0xABBAABBAABBAABBAABBAABBAABBAABBA
Mar
30
comment Is there an existing authorative definition of the cryptographic term 'pepper'
@orlp not if you are the defender and can make use of multiple cores, as password hashing is generally a single core operation. in this case the pepper forces both the defender and attacker to perform 8 operations, and the defender completes it in the same amount of time as if they had to do 1, but now the attacker will take 8 times longer for each attempt, of which they need to do a substantial quantity
Mar
30
comment Is there an existing authorative definition of the cryptographic term 'pepper'
@fgrieu a short pepper such as 3-bits can allow an 8-core system to perform a hash in parallel and only get 1 correct answer (to give a disadvantage to systems with less cores), and is intentional in password hashing schemes such as Catena. I believe this is a duplicate of crypto.stackexchange.com/questions/20578/…
Mar
29
comment Cryptography system by combining a block cipher and a stream cipher
how about something like, encrypt data with stream cipher, authenticate with block cipher in some specific mode?
Mar
29
comment Cryptography system by combining a block cipher and a stream cipher
why do you need to do this exactly?
Mar
27
comment The effect of truncated hash on entropy
I am pretty sure @fgrieu is correct, as input to the hash is handled as the key; imagine a known plaintext encrypted with a block cipher and truncated, the effect the key has on transforming the plaintext is what you are trying to measure
Mar
24
comment credit card number encryption using aes-ctr mode
@JohnDeters a 22 digit credit card number can still be encoded to be stored in less than 80 bits of data, and the expiration and cvv can be encoded in less than 30 bits, allowing a single block iteration to encrypt it. What countries have you seen using the larger card numbers, or are they non default merchant cards?
Mar
24
comment Is it safe to use PBEWithMD5AndDES?
@D.W if you are going to change the algorithm, I would strongly suggest also changing the hash function to at least SHA-1
Mar
24
comment What is the best hash for HMAC?
SHAKE is not at all appropriate for HMAC use, and SHA3 in general is not really designed for use with HMAC
Mar
23
answered credit card number encryption using aes-ctr mode
Mar
22
answered Replacing the PRF in PBKDF2 with Keccak