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[Ccrtp-devel] how to generate keystream segment for SRTP header
From: |
Yogesh Devidas Patil |
Subject: |
[Ccrtp-devel] how to generate keystream segment for SRTP header |
Date: |
Tue, 28 Jul 2009 20:33:31 +0530 |
Hi
I am implementing SRTP and have little confusion about it.
as per my understanding of SRTP RFC3711,
Initialization vector(IV) is generated as
IV = (salt_key << 16) XOR (SSRC << 64) XOR (packet_index << 16)
and keystream segment (required for AES ICM ) is generated as
Keystream_seg = E(k,IV) where k=Session key
i.e Keystream_seg = k XOR IV
is my understanding correct wrt SRTP standard??
Wherein AES ICM RFC3686, keystream segment consists
keystream_seg = NONCE || IV || Counter where Counter advances from initial
val=0.
I mean how to relate these keystream_seg forming units in AES
ICM(NONCE,IV,Counter) with SRTP header fields & fields computed from them??
Second, how should i generate Master Key on sender side??And how to derive
session keys from Master Key??
Thanks in advance!!
Thanks & Regards
Yogesh Patil
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- [Ccrtp-devel] how to generate keystream segment for SRTP header,
Yogesh Devidas Patil <=