Random data used by block cipher modes of operation to randomize the output in order to achieve semantic security. Also for other similar constructs in other iterative algorithms.
4
votes
5answers
318 views
Using CBC with a fixed IV and a random first plaintext block
What if, instead of using CBC mode in the normal way with a random IV, I used this approach:
Use a fixed IV (like a block of 0's).
Before encrypting, generate a random block and prepend it to the ...
1
vote
2answers
361 views
Why can't the IV be predictable when its said it doesn't need to be a secret?
I heard multiple times not to reuse the same IV and IV should be random but doesn't need to be secret. I also heard if the IV is something like sequential numbers or something predictable I should ...
6
votes
2answers
339 views
What's is the main difference between a key, an IV and a nonce?
What are the main differences between a nonce, a key and an IV. Without any doubt the key should be kept secret. But what about the nonce and the IV. What's the main difference between them and their ...
3
votes
3answers
566 views
Why is the IV passed in the clear when it can be easily encrypted?
The initialization vector (IV) is exclusive or'd against the plain text before encryption for the first block sent in order to prevent an attacker from learning that duplicate message blocks are being ...
3
votes
1answer
723 views
Does AES-CTR require an IV for any purpose other than distinguishing identical inputs?
I'd like to encrypt files deterministically, such that any users encrypting the same plaintext will use the same key and end up with the same ciphertext. The ciphertext should be private as long as ...
6
votes
2answers
477 views
Is using a predictable IV with CFB mode safe or not?
While writing this answer, I noted that NIST SP 800-38A says that (emphasis mine):
"For the CBC and CFB modes, the IVs must be unpredictable. In particular, for any given plaintext, it must not be ...
2
votes
0answers
154 views
Why not use CBC, not send IV, and assume first plaintext block is garbage? [duplicate]
Possible Duplicate:
Using CBC with fixed IV
Forgive me if this has been asked before, I looked but haven't seen any answers that suit.
Is there any danger in using CBC, encrypting a ...
7
votes
3answers
757 views
Is it okay to use a hash of a timestamp as the IV for AES?
The message format includes a datetime field in the clear. Is it okay to also use this field (or some hash thereof) as the initialization vector?
In this case, CBC is the mode being used.
3
votes
0answers
96 views
CBC with fixed IV but changing data [duplicate]
Possible Duplicate:
Using CBC with fixed IV
I am using AES in CBC mode.
For some reasons I have some issues for transmiting the IV. So I am using a fixed IV.
If the first 128bits of the ...
3
votes
4answers
278 views
Which block cipher modes of operation allow a predictable IV?
Recently I found out that in the modes CBC and PCBC the IV may be passed in cleartext but never must be predictable. However for this part of my app I rather have the IV be predictable and unique ...
3
votes
1answer
531 views
Why not use CTR with a randomized IV?
I'm currently reading the chapter of Cryptographic Engineering (Ferguson, Schneier, Kohno 2010) about block cipher modes of operation. They have recommended CBC with random IV instead of CTR due to ...
1
vote
4answers
398 views
Is my pseudo-random initialization vector secure?
How can I know if I am generating a secure pseudorandom initialization vector?
Currently I am planning to generate a pseudo-random initialization Vector using current date and time - is this secure ...
0
votes
2answers
201 views
Is the Blum Blum Shub PRNG suitable to create initialization vectors?
Is it a good idea to use a Blum Blum Shub Generator to create my initialization Vector (IV) in AES-OFB (Output Feedback Mode)?
