Time stamp in hMAC authentication
<p>as restful web api server, we supply our client a clientid and password. I think it is enough for the client to use clientid + hMAC(clientid hashed by password) for the authentication. </p>

<p>I have looked through some documents which advise to use Time stamp or even more information for the base string. I just cannot understand the meaning of that. </p>

<p>Could any guru help explain what exactly the time stamp would help for preventing attack or anything else?</p>