[asterisk-dev] VoIP Encryption

[John Todd]

>Hi all,
>
>Does anyone know any open source or tools to encrypt the VoIP 
>packets (Singnaling/RTP)? Becuase some ISPs  they are interpting the 
>Voice packets. so i we will use the encryption it will be very hard 
>for him to know the packets.
>
>Already i tried with openVPN but the quality is still bad and the 
>ISP interption is there.
>
>I will be appricaite if anyone can tell me the tools or library to 
>encrypt the packets.
>
>Thank You


I think that the discussion of IPSEC and various higher-layer VPN 
solutions is probably overkill for VoIP, in both complexity and in 
purpose.  I am a firm believer in applications-layer security.  VPNs 
are primarily used as a hack when the underlying protocols are 
insufficient to provide adequate protection for the transported data.

There are existing implementations of SRTP for SIP RTP with Asterisk 
(http://bugs.digium.com/view.php?id=5413) though the key exchange is 
still in the open as Asterisk does not support TCP/TLS/SMIME of any 
type for the SIP signalling.  Testers are welcome.

The IAX(2) implementations of encryption should be more widely 
publicized.  I will admit I got it working a while back, but have not 
implemented it everywhere because I don't have the time or 
inclination to get complex, undocumented, or fragile crypto working 
because it becomes more of a burden than the benefits it brings. 
Hopefully there can be a "README.crypto" file written some time... 
(yes, maybe I'll do it, but add it to the pile which might get looked 
at sometime in 2008.)

JT