title: Clarification about LE encryption field used in the LL_FEATURE_REQ and LL_FEATURE_RSP
body: <p>I sniffed with my Ubertooth One, some BLE packets between my Android phone and my BLE device, and I would like clarifications about a particular field and its meaning.</p>
  
  <p>After the connection is established, a <code>LL_FEATURE_REQ</code> is sent with the value of the <code>LE Encryption</code> field set to <code>0</code> (<code>false</code>).</p>
  
  <p>According to the offical documentation (BLUETOOTH SPECIFICATION Version 4.2 [Vol 6, Part B], 4.6 FEATURE SUPPORT):</p>
  
  <blockquote>
    <p>"When this information is sent from a Controller to a Host, a bit set to 0 indicates
    that the Link Layer Feature is not supported in this Controller; a bit set to 1
    indicates that the Link Layer Feature is supported in this Controller.</p>
    
    <p>When this information is sent from a Controller to a peer Controller, a bit set to 0
    indicates that the Link Layer Feature shall not be used by the Controllers; a bit
    set to 1 indicates that the Link Layer Feature may be used by the Controllers.
    "</p>
  </blockquote>
  
  <p>Also in the <code>LL_FEATURE_RSP</code> the <code>LL Encryption</code> field is set to <code>0</code> (<code>false</code>).</p>
  
  <p>So, according to this Message Sequence Chart (BLUETOOTH SPECIFICATION Version 4.2 [Vol 6, Part D]), before sending the <code>LL_FEATURE_REQ</code>, the Master device (my Android phone), first reads the supported features and then sends the request. 
  <a href="https://i.stack.imgur.com/NrCNV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NrCNV.png" alt="enter image description here"></a></p>
  
  <p>Does this mean that my Android device does not support communication encryption?</p>
  
  <p><strong>EDIT</strong>:</p>
  
  <p>Below is the Wireshark output (on the left is the the Bluetooth HCI snoop log from my Android phone, and on the right the packtet captured with my Ubertooth):</p>
  
  <p><a href="https://i.stack.imgur.com/36KVD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/36KVD.png" alt="enter image description here"></a></p>