# Need to generate new DH keys for every message in OTR

Going through the OTR specification I don't quite get why a new DH keys (and hence new symmetric key and hmac key) are generated for each message to be sent. Why is this necessary? I don't think it makes the argument for PFS any stronger. Also it does not have anything to do with deniability as well. Am I missing something here?

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One could alternatively use forward-secure symmetric cryptography. $\;$ –  Ricky Demer May 28 '14 at 19:07