[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [AVT] SRTP question
Hi
In fact, I think it was David who provided this test vector. As you say
though, the sole purpose is to provide an example, and it is in no way
connected to the use of HMAC.
If you are interested, I think I can also explain why the (rather large)
value of 94 octets is chosen. I believe it is a remainder from an
earlier version of SRTP that had the "TMMH" function as default MAC,
and this MAC required large keys.
Cheers
/Mats
Mark Baugher wrote:
Steffen
I think Karl wrote that section so I am copying him on my reply and he
can correct me if I'm wrong: The key length is there for the sole purpose
of illustrating key derivation and doe not imply that 94 octet key is to
be used for HMAC-SHA1.
regards, Mark
At 08:28 AM 7/12/2004, Steffen Fries wrote:
>Hi,
>
>I've got a question to the authentication key length in SRTP.
>RFC3711 describes the authentication function and the
>authentication key length within section 4.2 and the key
>derivation within section 4.3.
>Within section 8.2 the values for a SRTP policy are stated. For
>the session authentication key a default length of 160 bits is
>pointed out. Later in the key derivation test vector section B.3
>the authentication key length is mentioned with 94 octets.
>
>What is the reason for the length differences?
>
>Steffen
>
_______________________________________________
Audio/Video Transport Working Group
avt at ietf.org
https://www1.ietf.org/mailman/listinfo/avt