Linksys ATA Administration Guide
59
Secure Call Implementation
The CA public key is used to verify the MC received from the other end. If the MC is invalid, the
call will not switch to secure mode. The MC and the 1024-bit CA public key are concatenated
and base64 encoded into the single parameter
Mini Certificate
. The 512-bit private key is base64
encoded into the
SRTP Private Key
parameter, which should be kept secret, like a password.
(
Mini Certificate
and
SRTP Private Key
are configured in the Line tabs.)
Because the secure call establishment relies on exchange of information embedded in message
bodies of SIP INFO requests/responses, the service provider must ensure that the network
infrastructure allows the SIP INFO messages to pass through with the message body
unmodified.
Generating a Mini Certificate
Linksys provides a Mini Certificate Generator for the generation of mini certificates and private
keys.
•
Partners in North America can find the Mini Certificate Generator on the
SPA Utilities
page at the Linksys Partner Connection (LPC) at
Linksys.com
.
•
Partners in Europe, the Middle East, and Africa can find the Mini Certificate Generator on
the
Firmware and Tools
page at
linksys-itsp.com
.
NOTE: The partner sites require a logon.
The Mini Certificate Generator uses the following syntax:
gen_mc ca-key user-name user-id expire-date
Where:
•
ca-key
is a text file with the base64 encoded 1024-bit CA private/public key pairs for
signing/verifying the MC, such as the following:
9CC9aYUEBZmi3AmcqE9U1LxEOGwopaGyGOh3VyhKgi6JaVtQZt87PiJINKW8XQj3B9Qqe3VgYx
WCQNa335YCnDsenASeBxuMIEaBCYd1l1fVEodJZOGwXwfAde0MhcbD0kj7LVlzcsTyk2TZYTccnZ75TuTj
j13qvYs=
5nEtOrkCa84/mEwl3D9tSvu/Hd+C8u5SNk7hsAUZaA9TqH8Iw0J/
IqSrsf6scsmundY5j7Z5mK5J9uBxSB8t8vamFGD0pF4zhNtbrVvIXKI9kmp4vph1C5jzO9zjyY
pfGUfrpAuXb7/k=
•
user-name
is the name of the subscriber, such as “Joe Smith”. Maximum length is 32
characters
•
user-id
is the User ID of the subscriber, which must match exactly the user-id used in the
INVITE when making the call, such as “14083331234”. The maximum length is 16
characters.
•
expire-date
is the expiration date of the MC, such as “00:00:00 1/1/34” (34=2034).
Internally the date is encoded as a fixed 12B string: 000000010134
