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
132 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 ...
5
votes
1answer
790 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?
...
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
318 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
656 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
480 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 ...
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 ...
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 ...
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. ...
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 ...
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 ...
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 ...
