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.
6
votes
1answer
102 views
Encrypting short identifiers?
I am developing a webapp that does not reveal record count, because it hides the primary key. I am looking for a better way to do this.
My favorite idea is to encrypt the ID itself with a block ...
5
votes
1answer
130 views
Prevent cross domain form submission with nonce?
I haven't done much in web security before but am now in need to prevent a form from being submitted from anything but my own domain.
I know how to lock this down in an .htaccess file but the ...
2
votes
1answer
166 views
Are man-in-the-middle attacks against p2p systems realistic?
I'm implementing a DHT based on Kademlia following this paper.
The protocol described in this paper uses nonces to protect against man-in-the-middle attacks. The disadvantage is that latency gets ...
0
votes
0answers
62 views
Can I extend the validity of a nonce-code? [closed]
I made a URL Shortener on the admin interface of my website. The provider of the Shortener (YOURLS) secured the admin page with a security token, a nonce with 10 to 12 characters. I copied the whole ...
4
votes
2answers
316 views
Do Client Nonces enhance the security of HTTP Digest Auth?
As far as I understand the answer at
http://security.stackexchange.com/a/3024/13447, client nonces are meant to prevent attackers from amortizing the costs of brute-force hash computations by being ...
6
votes
2answers
653 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 ...
3
votes
3answers
499 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()
...
5
votes
1answer
785 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?
...
5
votes
1answer
479 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 ...
1
vote
3answers
287 views
Three Message Authentication Protocol
I have a protocol where "A" initiates communication with "B". "B" then sends a challenge to check if "A" is really "A". "B" does not remember sending the challenge so "A" has to respond by sending the ...
6
votes
3answers
587 views
chosen plaintext attacks against MD5 and SHA1
According to http://tools.ietf.org/html/rfc2617#section-4.9, having the server chose a nonce but not having the client chose a nonce opens up Digest Access authentication to chosen plaintext attacks. ...
1
vote
1answer
418 views
Nonce construction for CTR mode (Mcrypt)
Edit: I'll put up this more clearly.
By the most simplest form, I'm asking that if I AES encrypt in CTR more with Mcrypt (using PHP), can I create the "IV" by just simply reading 16 bytes from ...
7
votes
1answer
2k views
SSL replay attack when client/server random is missing
Hey studying the SSL protocol, I'm wondering how can someone be able to do a replay attack if the server nonce is missing? All the material I find says that nonces prevent it, but theres no examples ...
27
votes
4answers
5k 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 ...
9
votes
1answer
1k views
TLS replay attack - requirements of the serverHello nonce
As you all know, the SSL/TLS protocol requires both client and server to exchange (in clear text) a random number or nonce. This is presumably used to prevent replay attacks.
It is not clear to me ...
13
votes
3answers
2k 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 ...
