[Asterisk-Users] Encryption

[Steve Underwood]

And SRTP uses........ AES!

Steve


Brian West wrote:

>I understand AES can do this.
>
>bkw
>
>On Thu, 25 Dec 2003, Steve Underwood wrote:
>
>  
>
>>Steven Critchfield wrote:
>>
>>    
>>
>>>On Wed, 2003-12-24 at 19:11, Mahoney, Matt wrote:
>>>
>>>
>>>      
>>>
>>>>Hi,
>>>>
>>>>
>>>>Does asterisk support any kind of voice encryption?
>>>>
>>>>
>>>>        
>>>>
>>>Not right now. As I understand it, it is a problem with the fact that
>>>each packet would have to be able to be decrypted even if packets in the
>>>stream are lost. In the long run it is going to be a question of how
>>>secure do you need it to be. Afaik, the good encryption methods are
>>>stream based, and the loss of packets would kill the decryption.
>>>
>>>Add to that the problem of finding some encryption method that can deal
>>>with small packets without adding a lot of overhead. Each voice packet
>>>in IAX with GSM compression isn't very long. The voice data is only 33
>>>bytes.
>>>
>>>
>>>      
>>>
>>The need to tolerate packet losss means a continuous stream cypher can't
>>be used. That reduces the quality of the ciphering, but it can still be
>>pretty good. You know the packet sequence number (at least with RTP you
>>do), so some forms of sequentially changing encryption can still be
>>used. SRTP has been through the process of trying to deal with this in
>>the most effective manner, but doesn't seem to be widely used right now.
>>Free implementations exists - see srtp.sourceforge.net. I guess it
>>should be adaptable to IAX.
>>
>>Regards,
>>Steve
>>
>>    
>>