4
votes
3answers
124 views

Is it secure to use Diffie-Hellman key agreement to generate a nonce?

I have a system, using AES, in one of the modes that uses a nonce and authentication. We have a pre-shared key, and to agree about initial nonce we could use Diffie-Hellman, using the resulting ...
5
votes
1answer
98 views

Condensed ElGamal + AES

In normal ElGamal encryption, the encrypted message is a pair (gb, gabM) - that is, the actual "encryption" is simply multiplication by the shared secret ...
2
votes
2answers
255 views

At what stage is DHE and RSA used during the SSL/TLS handshake?

At what stage of the SSL/TLS handshake is the DHE and RSA used and what is the purpose of using a pre-master secret when you could just use RSA to exchange the symmetric key (i.e. AES) for further ...
3
votes
2answers
229 views

Should I bother implementing DH + AES, or leave it to a library like Crypto++

I'm making a C++ back end for an application that'll heavily rely on AES-256 and DH. Should I trust third party libraries, or spend (lots of) time to learn about cryptographic implementation and write ...
0
votes
1answer
318 views

Diffie-Hellman Secret Exponent Size and Shared Secret Usage [closed]

I'm developing my own protocol and I'll use Diffie-Hellman to achieve PFS. It will work in this way: The symmetric encryption algorithm will be AES_256_CBC. The DH parameters will be: P: a 2048-bit ...
6
votes
2answers
530 views

Vulnerabilities if encrypting the same data with 2 different keys

Let's say that Alice and Bob complete a key exchange and then Alice uses that key k1 to encrypt a 256-bit key kaes1 and sends it ...
4
votes
2answers
2k views

AES encryption using a Diffie-Hellman key exchange

I have two systems which need to encrypt their communication by AES-128. The key for the AES encryption should be exchanged with the Diffie-Hellman (DH) algorithm. Now, I've read about DH and got a ...
1
vote
0answers
99 views

openssl logs showing keyblock length of only 88 bytes instead of 136 bytes

I was decrypting TLS encrypted data from wireshark using the openssl(TLS1.0 version) TLS logs which provides the complete key block which of size 136 bytes.Now i moved to TLS(1.2 version) in that Key ...