To summarize ECDH_compute_key, you provide a pointer to one party's EC
public Key, a pointer to another party's EC private key, and a pointer
to a hashing routine and the function will compute a shared secret
value.

However, there is much more to key exchange than merely understanding
how to use this function. It is more important to know how to use it
correctly.

I suggest that you read and understand the concepts of key exchange
relating to ECC and ECDH in NIST Special Pub 800-56A
http://csrc.nist.gov/publications/ni...6A_Revision1_M
ar08-2007.pdf

Determine whether your application requires the use of ephemeral keys
and whether your key exchange needs to be one way or two way. Then
start looking into the mechanics of the actual API calls you will need
to use.

Also keep in mind that good security design necessitates that you use
symmetric, asymmetric and hashing algorithms of equivalent strength.

Bill

-----Original Message-----
From: owner-openssl-users@openssl.org
[mailtowner-openssl-users@openssl.org] On Behalf Of Sateesh Babu
Sent: January 11, 2008 7:03 AM
To: openssl-users@openssl.org
Subject: How to use ECDH_compute_key

Hi,
There is not enough documentation on the usage of ECDH_compute_key.
Can anyone please help me in understanding its usage?

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