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11h
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?
15h
comment cryptography system by combining a block cipher and a stream cipher
why do you need to do this exactly?
1d
comment Who are cryptography programmers responsible to?
Question is not about cryptography
2d
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
Mar
21
comment Replacing the PRF in PBKDF2 with Keccak
Keccak is substantially faster in hardware than SHA-256, you would make the function MORE vulnerable to brute force attack
Mar
16
comment Rijndael S-boxes: Where do the $\mu$ and $\nu$ polynomial ring elements come from?
Using your format, the most simple poly is x^2 + x + 1
Mar
16
comment Rijndael S-boxes: Where do the $\mu$ and $\nu$ polynomial ring elements come from?
I use the 1F format in my s-box generation software as well. I am confident the polynomial and vector used for Rijndael were not optimal, nor was the polynomial the simplest
Mar
16
comment Requested to encrypt data with AES256, digital certification, timestamped
Correct. You encrypt the data, encrypt the AES key with the recipient public key, then sign with your private key.
Mar
16
comment Requested to encrypt data with AES256, digital certification, timestamped
look up Hybrid Cryptosystem
Mar
16
comment Rijndael S-boxes: Where do the $\mu$ and $\nu$ polynomial ring elements come from?
2nd , the polynomials are different, but return the same result if processed differently. Yours (4+3+2+1+0) is in the 1F format, which I also use in my software. Also the AES s-box does fixed point issues, despite the design criteria. They chose v incorrectly
Mar
16
comment Rijndael S-boxes: Where do the $\mu$ and $\nu$ polynomial ring elements come from?
2 things, first, this is a dupe of my question crypto.stackexchange.com/questions/17932/…
Mar
15
comment Why does consecutive permutations or consecutive substitutions not enhance security?
actually with AES, that may not be entirely accurate, as the permutation layer does not provide complete diffusion. performing it twice will diffuse the input better
Mar
14
comment Block cipher mode with diffusion on ciphertext
@dhuCerbin why not just add a checksum or authentication code to the message?
Mar
13
comment Inconsistent terminology for ciphers and algorithms
I would define "cipher" as a cryptographic algorithm that encodes data through use of a key, and that would include asymmetric algorithms which use a different key to decrypt.
Mar
11
comment CTR HMAC SHA256 implementation
@JohnSmith you are leaving the user open to a dangerously high probability of nonce reuse. you need the nonce to be foolproof