Counter Mode (CTR) is an encryption mode, that builds a random-access stream-cipher from a block-cipher.
0
votes
2answers
104 views
Recommended authenticated stream cipher for minimum overhead?
I'm running my TCP/IP protocol secured by encrypting each packet with AES128/CBC, bundling a SHA256 HMAC over that packet.
This causes quite a bit of space overhead for small packets, so at first I ...
1
vote
1answer
70 views
Counter Mode: static IV but different keys [duplicate]
Given we are using AES counter mode, suppose we randomly generate several keys, all of them are using same IV (say, zeros). Does this lead to any security issue?
I know that in CTR mode, same key-iv ...
1
vote
1answer
111 views
Proper uses for CTR and CBC AES block cipher modes
Assuming the following:
Key is randomly generated is being used (32 bytes+)
IV is also randomly generated
Crypto random key generator is used
Data being encrypted contains common bytes like ...
1
vote
2answers
251 views
AES+CTR+HMAC Encryption and Authentication on an Arduino
In my project we would like to encrypt and authenticate the the communication channel between our server and our Arduino nodes, which relies on an underlying TCP channel.
We have chosen AES in CTR ...
0
votes
2answers
131 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.
K[0] = Master key
C[i] = E(K[i],P[i]), K[i]=F(K[i-1])
This is similar to the counter ...
2
votes
2answers
291 views
AES-CTR vulnerability to cryptographic oracle
I am new to cryptographic issues and from what I googled so far I could not retrieve the information I need.
Consider the use of AES-128 in CTR mode.
Let M be the set of possible plaintexts, for ...
1
vote
1answer
394 views
AES CBC mode or AES CTR mode recommended?
what's benefits and disadvantages of CBC vs CTR ? which one is more secure ?
2
votes
1answer
172 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 ...
1
vote
1answer
124 views
How many different keystreams can I produce with AES in Counter Mode?
I'm using a 64-bit nonce (incremented between the streams) and a 64-bit counter (incremented within a stream) for AES in CTR mode. How many different key streams can I produce with this setup?
0
votes
1answer
784 views
Counter Mode in Advanced Encryption Standard(AES) Algorithm
In Advanced Encryption Standard, If I used "Counter Mode", in it's nonce value, what should I do?
ex. should I divide the nonce value into two? ex. I have 128-bit of nonce, should I divide it from ...
1
vote
1answer
330 views
Why must IV/key-pairs not be reused in CTR mode?
Many sources mention that IVs must not be reused with the same key in CTR mode, for encrypting 2 different pieces of data, because that totally destroys security - but I haven't found an explanation ...
4
votes
1answer
438 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 ...
2
votes
3answers
1k views
Which one of the Block Cipher modes is the best?
I have two questions regarding the Block Cipher Modes:
First: 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 ...
4
votes
4answers
518 views
Is SHA-256 secure as a CTR block cipher?
Generate a 256-bit random nonce. XOR it with a 256-bit reusable symmetric key. This is x.
We represent numbers in simple binary instead of a counting function. ...
4
votes
2answers
213 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.
