Openssl- How to set the ciphers?

In security network (like SSL, TLS), the client and server choose ciper which will be used during the communication.

Cipher is, the name of algorighm used in encryption, decryption theory.

In SSL(TLS) handshake, "Client Hello" time, client sends the list of cipher to the server. After that, in "Server Hello" time, the server sends the exact cipher which used for encryption&decryption during the communication.

 

 

So, How to set this up??

It's not that difficult. we just set the value in server application setup file. for example,

in Asterisk, we put the list of cipher can be used.  like this;

 

tlscipher=AES128-SHA:AES128-MD5

tlscipher=ALL

 .... so on...

 

 

How to enter cipher string? Refer this link :

Go to openssl website 

 

and add one more,

After installing openssl, put this command;

>openssl ciphers -v

 

we can see the list of valid cipher.

 

ECDHE-RSA-AES256-SHA    SSLv3 Kx=ECDH     Au=RSA  Enc=AES(256)  Mac=SHA1 ECDHE-ECDSA-AES256-SHA  SSLv3 Kx=ECDH     Au=ECDSA Enc=AES(256)  Mac=SHA1 DHE-RSA-AES256-SHA      SSLv3 Kx=DH       Au=RSA  Enc=AES(256)  Mac=SHA1 ...skip this part.... EXP-RC4-MD5             SSLv3 Kx=RSA(512) Au=RSA  Enc=RC4(40)   Mac=MD5  export

 

* It's only for the application which uses Openssl library. So for the application uses another ssl library, follow the operation of that library.