usually secret information used as input to various kinds of cryptographic algorithms, like encryption, signature, MAC, to select the concrete transformation done by the algorithm.
4
votes
1answer
463 views
How does GPG verify succesful decryption?
How does GPG (or other programs using the OpenPGP file format) verify that it has succeeded with decryption (for symmetrically encrypted data)?
Is something appended to the clear text so there exist ...
5
votes
1answer
179 views
Why are the random exponents so much bigger in the Socialist Millionaire protocol versus Diffie-Hellman key exchange?
Section 8, Security considerations, of RFC3526, which defines groups used for Diffie-Hellman has a table recommending some random exponent sizes. In particular, it says:
The strength of a key ...
3
votes
3answers
182 views
Derived Shared Key vs Distinct Keys?
I've seen a lot of 2-party applications that derive a shared key from distinct keys created by each party.
Why is this technique employed? Would it not be better to use those two distinct keys for ...
3
votes
2answers
622 views
How key materials are generated in SSL V3 from master secret
The generation of key materials is given by
...
4
votes
1answer
514 views
How does a key wrapping like RFC 3394 secure my cryptographic keys?
So I'm messing around in the BouncyCastle library with the RFC 3394 AES Key Wrap engine and I'm trying to understand the benefit of it.
The problem I'm running into is how to store keys securely on a ...
4
votes
4answers
496 views
How to require two keyholders to decrypt a document?
I want to create a system to encrypt a document and store it with a 3rd party, but not have the 3rd party be able to decrypt it until some unspecified later date. It seems like the solution would be ...
6
votes
2answers
255 views
Key Length & Hashing
I need to use a hash function to generate a 128-bit key for a symmetric cipher. The specific cipher is from the eStream portofolio, called Rabbit.
I am using the SRP protocol for authentication (a ...
2
votes
1answer
117 views
A set of key pairs and one hash to secure them
I have a simple problem: I have a set of users' ECDSA key pairs, and say I want to encrypt them with a simple algorithm. I have access to one variable that uniquely identifies the user, so I hash it ...
2
votes
2answers
360 views
Public key generation in homomorphic encryption schemes
Is there any way to effectively generate valid distributed public key in schemes like ElGamal or Benaloh for a number of participants? There's no need in private keys since there's no intent to ...
10
votes
3answers
586 views
Where do I securely store the key for a system where the source is visible?
I have a customer with an Access database (ugh!) in which credit cards are stored in plaintext (yikes!), so amongst other changes I'm doing in the app, I'm applying some encryption in there.
I've ...
10
votes
5answers
640 views
Why does PBKDF2 xor the iterations of the hash function together?
The definition of PBKDF2 states that I obtain a derived key* by calling a pseudorandom function a bunch of times recursively:
...
15
votes
7answers
1k views
How can SSL secure a two-way communication with only one key-pair?
As I understand it, SSL involved the use of a public-private key pair. How does this enable two-way communication?
Suppose I have some server with which I wish to communicate securely. I connect to ...
