1
vote
1answer
102 views

Difference between plain AES CTR and “CCM-style” CTR

I am trying to adapt the following function from SJCL, which does "AES-CCM" style CTR encryption, to do "pure CTR" encryption. I am playing around with SIV and would rather use this well-reviewed ...
4
votes
2answers
168 views

Why does CTR mode XOR the plaintext into the output of the block cipher rather than XORing the plaintext into the input of the block cipher?

As I understand it, CTR mode essentially turns a block cipher into a stream cipher like so: ...
7
votes
1answer
417 views

What is wrong with AES-CTR-HMAC-SHA256 - or why is it not in TLS?

It seems the only specified CTR mode ciphers in TLS are all GCM based. GCM ciphers run AES-CTR and do authenticated encryption with a MAC based on Galois-field ...
4
votes
2answers
213 views

CTR mode nonce with aggressive key rotation policy

I'm writing a small encryption library which will be required to use the shortest possible amount of overhead for describing ciphertexts. I want to use CTR mode with a 6-byte random nonce. Normally ...
1
vote
2answers
208 views

Why nobody considers counter re-keying as a standard Block Cipher Mode?

One of the simplest possible cipher modes is setting each successive key as a function F of the previous one. ...
6
votes
1answer
276 views

Why doesn't CTR mode require blocking?

I've been reading a bit about block cipher modes and I have a relatively straightforward question regarding CTR. In essence, I was hoping you guys would be kind enough to validate my understanding of ...
6
votes
1answer
1k views

Deterministic nonces in CTR mode

I want to encrypt a file with AES in CTR mode. I have a 256 bit master key and the file. Given these, the encryption must be deterministic, so I can't use a random nonce in the usual way. Fortunately ...
4
votes
3answers
3k views

Which one of the Block Cipher modes is the best?

I have two questions regarding the Block Cipher Modes: Which one of the modes is considered the best? I know CBC has a problem of IV since the next block of the plain text is XORed with the result ...
4
votes
2answers
292 views

Is it safe to store initial counter value for AES-CTR alongside with ciphertext?

The initial counter value can actually be thought of as a sort of IV, which I assume is safe to transmit with the ciphertext, but I really want to be sure that this is indeed safe.