Re: Find out IV length

2022-08-17 Thread Matt Caswell 




On 17/08/2022 06:30, Kreissl, Jochen wrote:

Hi,

given an SSL* or respectively an SSLCIPHER* struct, how can I figure out 
the length of the IV used by the negotiated cipher of the handshake?


I noticed that EVP_CIPHER has a metod to query this information, but I 
also don’t find a way to get an EVP_CIPHER from SSL*.


Any pointers (heh) would be very helpful, thanks.

Cheers



Given an SSL_CIPHER structure the associated EVP_CIPHER can be obtained 
using something like this:


EVP_CIPHER *ciph = 
EVP_get_cipherbyname(OBJ_nid2sn(SSL_CIPHER_get_cipher_nid(sslciph)))


But note that IV handling in TLS is a little complicated with the actual 
IV that is used for an actual encryption/decryption operation being 
composed of different elements. The details of which vary by ciphersuite 
and protocol version.


Matt

Find out IV length

2022-08-16 Thread Kreissl, Jochen 
Hi,

given an SSL* or respectively an SSLCIPHER* struct, how can I figure out the 
length of the IV used by the negotiated cipher of the handshake?
I noticed that EVP_CIPHER has a metod to query this information, but I also 
don't find a way to get an EVP_CIPHER from SSL*.
Any pointers (heh) would be very helpful, thanks.

Cheers