AudioCodes Mediant 1000

Version 7.2 397 Mediant 1000B Gateway & E-SBC
User's Manual 19. Coders and Profiles
Parameter Description
^31|1:1
a=crypto:3 AES_CM_128_HMAC_SHA1_80
inline:bnuYZnMxSfUiGitviWJZmzr7OF3AiRO0l5Vnh0kH|2
^31
The first crypto line includes the MKI parameter "1:1". In the 200
OK response, the device selects one of the crypto lines (i.e., '2' or
'3'). Typically, it selects the first line that supports the crypto suite.
However, for SRTP-to-SRTP in SBC sessions, it can be
determined by the remote side on the outgoing leg. If the device
selects crypto line '2', it includes the MKI parameter in its answer
SDP, for example:
a=crypto:2 AES_CM_128_HMAC_SHA1_80
inline:R1VyA1xV/qwBjkEklu4kSJyl3wCtYeZLq1/QFuxw|2
^31|1:1
If the device selects a crypto line that does not contain the MKI
parameter, then the MKI parameter is not included in the crypto
line in the SDP answer (even if the SRTPTxPacketMKISize
parameter is set to any value other than 0).
Note: The corresponding global parameter is EnableSymmetricMKI.
MKI Size
mki-size
[IpProfile_MKISize]
Defines the size (in bytes) of the Master Key Identifier (MKI) in SRTP
Tx packets.
The valid value is 0 to 4. The default is 0 (i.e., new keys are
generated without MKI).
Note:
 Gateway application: The device only initiates the MKI size.
 SBC application: The device can forward MKI size as is for
SRTP-to-SRTP flows or override the MKI size during negotiation.
This can be done on the inbound or outbound leg.
 The corresponding global parameter is SRTPTxPacketMKISize.
SBC Enforce MKI Size
sbc-enforce-mki-size
[IpProfile_SBCEnforceMKISiz
e]
Enables negotiation of the Master Key Identifier (MKI) length for
SRTP-to-SRTP flows between SIP networks (i.e., IP Groups). This
includes the capability of modifying the MKI length on the inbound or
outbound SBC call leg for the SIP entity associated with the IP
Profile.
 [0] Don't enforce = (Default) Device forwards the MKI size as is.
 [1] Enforce = Device changes the MKI length according to the
settings of the IP Profile parameter, MKISize.
Reset SRTP Upon Re-key
reset-srtp-upon-re-key
[IpProfile_ResetSRTPStateUp
onRekey]
Enables synchronization of the SRTP state between the device and
a server when a new SRTP key is generated upon a SIP session
expire. This feature ensures that the roll-over counter (ROC), one of
the parameters used in the SRTP encryption/decryption process of
the SRTP packets is synchronized on both sides for transmit and
receive packets.
 [0] Disable = (Default) ROC is not reset on the device side.
 [1] Enable = If the session expires causing a session refresh
through a re-INVITE, the device or server generates a new key
and the device resets the ROC index (and other SRTP fields) as
done by the server, resulting in a synchronized SRTP.
Note:
 If this feature is disabled and the server resets the ROC upon a