title: How to specify certificate, key and root certificate with httr for certificate based authentication?
body: <p>I am trying to access data using httr library from server which expects certificate based authentication. I have certificate (cert.pem), key file (key.pem) and root certificate (caroot.pem)</p>
  
  <p>Following curl works.</p>
  
  <blockquote>
    <p>curl -H "userName:sriharsha@rpc.com" --cert cert.pem --key certkey.key --cacert caroot.pem <a href="https://api.somedomain.com/api/v1/timeseries/klog?limit=1" rel="noreferrer">https://api.somedomain.com/api/v1/timeseries/klog?limit=1</a></p>
  </blockquote>
  
  <p>How can specify certkey.key and caroot.pem to httr GET request. I am trying with following R command but couldn't find option to specify cert key and caroot.</p>
  
  <blockquote>
    <p>cafile=????
    r&lt;-GET("<a href="https://api.somedomain.com/api/v1/timeseries/klog" rel="noreferrer">https://api.somedomain.com/api/v1/timeseries/klog</a>", query = list(limit = 1), add_headers("userName"= "sriharsha@rpc.com"), config(cainfo = cafile, ssl_verifypeer=FALSE), verbose())</p>
  </blockquote>
  
  <p>Thus I am looking for equivalent options of httr for (--cert, --key and --cacert) of curl.</p>