Linked Questions

0 votes
2 answers
124 views

Randomly initialised global counter used to encrypt the kth message with $\operatorname{IV} = \operatorname{IV} + k \hspace{5mm} mod \hspace{5mm} 2^n$ [duplicate]

The use of an increasing IV is not secure for a block cipher. That is, using a random IV for the first message then $\operatorname{IV} + 1$ for the second , $\operatorname{IV}+ 2$ for the 3rd etc. How ...
Kivi's user avatar
  • 1
1 vote
0 answers
117 views

AES CBC Initialization vector - Security issues [duplicate]

I have 2 questions regarding security issues related to initialization vectors used in AES CBC Consider that I'm using a sequence number (which increments with every encryption) as an initialization ...
Mukund Manikarnike's user avatar
0 votes
0 answers
58 views

CBC Operation with Known IV [duplicate]

I am trying to understand how XOR operation can lead us to know the plaintext if we can predict the iv using the chosen plaintext attack game.
CryptoGuru's user avatar
83 votes
9 answers
138k views

Should I use ECB or CBC encryption mode for my block cipher?

Can someone tell me which mode out of ECB and CBC is better, and how to decide which mode to use? Are there any other modes which are better?
midhunhk's user avatar
  • 1,151
33 votes
2 answers
12k views

7zip : Why does encrypting the same file with AES-256 not give the same output?

Using 7-zip 19.00, on Windows 10 1909, build 18363.592, I encrypted a text file with the contents "hello there" using AES-256 and the password "123". I did this two times, the exact same procedure, ...
super's user avatar
  • 463
24 votes
3 answers
39k views

How can Cipher Block Chaining (CBC) in SSL be attacked?

I am trying to understand how CBC-mode in SSL/TLS can be attacked. I have been looking around online but all examples and explanations are very hard to understand and follow. Can you give a simple ...
antonpug's user avatar
  • 341
3 votes
3 answers
5k views

Is CTR more secure than CBC?

In cryptography, a block cipher mode of operation is an algorithm that uses a block cipher to provide information security such as confidentiality or authenticity. A block cipher by itself is only ...
moyu's user avatar
  • 73
5 votes
3 answers
804 views

CVE-2024-31497, nonces and random numbers: Can someone explain, please?

Regarding CVE-2024-31497 a German article "Nur NIST P-521 betroffen: PuTTY-Lücke kompromittiert private SSH-Schlüssel" wrote something about a vulnerability in PuTTY. The issue was claimed ...
U. Windl's user avatar
  • 229
10 votes
1 answer
2k views

Which block cipher parameters should be kept secret?

Which of the parameters of a block cipher (e.g., algorithm name, mode of operation, IV (if any), key length) are essential to keep secret?
Emily's user avatar
  • 101
6 votes
1 answer
10k views

CBC with a fixed or random IV

I have three questions related to the use of IV within CBC mode of operation: Why, exactly, is it so bad to have a fixed (or predictable) IV in CBC mode? An example would be great! Given 1., why is a ...
Joe's user avatar
  • 121
8 votes
2 answers
2k views

CBC variant: why encrypt the nonce with a different key?

I am a newbie at cryptography. I understand the CBC encryption, somewhat. You don't want to use the same "IV" for every message because then the ciphers are not very random. My question is regarding ...
Maty's user avatar
  • 81
2 votes
2 answers
2k views

using different IV and SALT with AES-CBC but same KEY

I'm working on this project where a client can send a message, now obviously sending it in plainText is not very smart. So I decided to Encrypt it with AES-CBC. Now, each time I encrypt something, the ...
Omer Enes's user avatar
8 votes
1 answer
367 views

Predictable, but private IV in CBC

It is said that a predictable IV is dangerous, because you can do adaptive chosen plaintext attacks. But if the IV is never seen to the attacker, is it still dangerous? What I mean, is that the IV is ...
Kethan's user avatar
  • 81
2 votes
1 answer
2k views

Is it safe to AES-CBC and AES-CMAC both using the same key?

There is a very similar question (Using a derived key for CMAC) but it doesn't quite answer this one (at least for me it does not). I have a situation where I need to transfer some data. My data has ...
traxonja's user avatar
3 votes
2 answers
2k views

How to defend AES against chosen-plaintext attack?

I have a server which encrypts files with the same AES key. Users can upload a file and download its encrypted version. A user can upload as many files as he wants. Users can decrypt the documents via ...
user1552545's user avatar

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