a random number that is only used once. It is generated at the beginning of a communication by one communication partner and has to be sent back by the other one in order to prevent replay attacks.

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43
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4answers
15k views

What is the use of a client nonce?

After reading Part I of Ross Anderson's book, Security Engineering, and clarifying some topics on Wikipedia, I came across the idea of Client Nonce (cnonce). Ross never mentions it in his book and I'm ...
11
votes
1answer
4k views

When using AES and CBC, is it necessary to keep the IV secret?

If I encrypt some data with a randomly generated Key and Initialization Vector, then store all three pieces of information in the same table row; is it necessary to encrypt the IV as well as the Key? ...
18
votes
3answers
5k views

How long should a random nonce be?

NIST provides good guidelines on the length of keys and hashes for various algorithms. But I don't see anything specifically on the length of a random or pseudo-random nonce (number used once). If ...
8
votes
2answers
4k views

when to use nonce?

I have trouble understanding nonce. I read a very good answer related to nonce by @Thomas Pornin, but it is too complicated for me as I am new to cryptography. From what I know, nonce is used to ...
4
votes
3answers
2k views

optimal way to salt password?

A good way to salt password? I have read a few answers related to salting password. But I started to get confused. I came across few functions people used to generate salt like: mcrypt_create_iv() ...
7
votes
1answer
1k views

Is it possible to have stateless server nonces in HTTP Digest

When implementing a HTTP Digest server, there's the issue of nonces. Server nonces (as opposed to client nonces) must be issued by the server may be re-used by clients as long as the server allows ...