diff --git a/index.html b/index.html
index b5c7858..53302b5 100644
--- a/index.html
+++ b/index.html
@@ -325,6 +325,17 @@ <h2>Device access is powerful</h2>
       <section class="informative">
         <h2>Attacks on devices</h2>
 
+        <p>
+          Communication from websites can break the security model of some devices,
+          which assume they only receive messages from
+          the trusted operating system of a remote device.
+          Human Interface Devices are a prominent example,
+          where allowing a website to communicate would allow that site to log keystrokes.
+          This specification includes a blacklist of
+          such vulnerable services, characteristics, and descriptors
+          to prevent websites from taking advantage of them.
+        </p>
+
         <p>
           We expect that many devices are vulnerable to unexpected data delivered to their radio.
           In the past, these devices had to be exploited one-by-one,
@@ -587,6 +598,11 @@ <h2>Device Discovery</h2>
                   If any of the <a>BluetoothUUID.getService</a> calls threw an exception,
                   <a>reject</a> <var>promise</var> with that exception and abort these steps.
                 </li>
+                <li>
+                  If any <var>service</var> in <var>services</var> is <a>blacklisted</a>,
+                  <a>reject</a> <var>promise</var> with a <a>SecurityError</a>
+                  and abort these steps.
+                </li>
                 <li>Append <code>{services: <var>services</var>}</code> to <var>uuidFilters</var>.</li>
                 <li>Add the elements of <var>services</var> to <var>requiredServiceUUIDs</var>.</li>
               </ol>
@@ -600,6 +616,9 @@ <h2>Device Discovery</h2>
               If any of the <a>BluetoothUUID.getService</a> calls threw an exception,
               <a>reject</a> <var>promise</var> with that exception and abort these steps.
             </li>
+            <li>
+              Remove from <var>optionalServiceUUIDs</var> any UUIDs that are <a>blacklisted</a>.
+            </li>
           </ol>
         </li>
         <li>
@@ -1606,6 +1625,11 @@ <h2><dfn>BluetoothGATTRemoteServer</dfn></h2>
             If <a>BluetoothUUID.getService</a> threw an exception,
             return <a>a promise rejected with</a> that exception and abort these steps.
           </li>
+          <li>
+            If <var>service</var> is <a>blacklisted</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             <a>Query the Bluetooth cache</a> for
             the first primary GATT service
@@ -1633,6 +1657,11 @@ <h2><dfn>BluetoothGATTRemoteServer</dfn></h2>
             If <a>BluetoothUUID.getService</a> threw an exception,
             return <a>a promise rejected with</a> that exception and abort these steps.
           </li>
+          <li>
+            If <var>service</var> is present and is <a>blacklisted</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             <a>Query the Bluetooth cache</a> for the primary GATT services
             on <code>this@[[\representedDevice]]</code>
@@ -1738,6 +1767,11 @@ <h2><dfn>BluetoothGATTService</dfn></h2>
             If <a>BluetoothUUID.getCharacteristic</a> threw an exception,
             return <a>a promise rejected with</a> that exception and abort these steps.
           </li>
+          <li>
+            If <var>characteristic</var> is <a>blacklisted</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             <a>Query the Bluetooth cache</a> for
             the first GATT characteristic within this Service
@@ -1764,6 +1798,11 @@ <h2><dfn>BluetoothGATTService</dfn></h2>
             If <a>BluetoothUUID.getCharacteristic</a> threw an exception,
             return <a>a promise rejected with</a> that exception and abort these steps.
           </li>
+          <li>
+            If <var>characteristic</var> is present and is <a>blacklisted</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             <a>Query the Bluetooth cache</a> for
             the GATT characteristics that are within this Service and,
@@ -1791,6 +1830,11 @@ <h2><dfn>BluetoothGATTService</dfn></h2>
             If <a>BluetoothUUID.getService</a> threw an exception,
             return <a>a promise rejected with</a> that exception and abort these steps.
           </li>
+          <li>
+            If <var>service</var> is <a>blacklisted</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             <a>Query the Bluetooth cache</a> for the first GATT included service
             within this Service whose UUID is <var>service</var>,
@@ -1816,6 +1860,11 @@ <h2><dfn>BluetoothGATTService</dfn></h2>
             If <a>BluetoothUUID.getService</a> threw an exception,
             return <a>a promise rejected with</a> that exception and abort these steps.
           </li>
+          <li>
+            If <var>service</var> is present and is <a>blacklisted</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             <a>Query the Bluetooth cache</a> for
             the GATT Included Services that are within this Service and,
@@ -1928,6 +1977,11 @@ <h2><dfn>BluetoothGATTCharacteristic</dfn></h2>
             If <a>BluetoothUUID.getDescriptor</a> threw an exception,
             return <a>a promise rejected with</a> that exception and abort these steps.
           </li>
+          <li>
+            If <var>descriptor</var> is <a>blacklisted</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             <a>Query the Bluetooth cache</a> for
             the first GATT descriptor within this Characteristic
@@ -1954,6 +2008,11 @@ <h2><dfn>BluetoothGATTCharacteristic</dfn></h2>
             If <a>BluetoothUUID.getDescriptor</a> threw an exception,
             return <a>a promise rejected with</a> that exception and abort these steps.
           </li>
+          <li>
+            If <var>descriptor</var> is present and is <a>blacklisted</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             <a>Query the Bluetooth cache</a> for
             the GATT descriptors that are within this Characteristic and,
@@ -1975,6 +2034,11 @@ <h2><dfn>BluetoothGATTCharacteristic</dfn></h2>
           and run the following steps <a>in parallel</a>:
         </p>
         <ol>
+          <li>
+            If <code>this.uuid</code> is <a>blacklisted for reads</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             Let <var>characteristic</var> be the <a>Characteristic</a>
             that <code>this</code> represents.
@@ -2018,6 +2082,11 @@ <h2><dfn>BluetoothGATTCharacteristic</dfn></h2>
           MUST run the following steps:
         </p>
         <ol>
+          <li>
+            If <code>this.uuid</code> is <a>blacklisted for writes</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             Let <var>characteristic</var> be the <a>Characteristic</a>
             that <code>this</code> represents.
@@ -2076,6 +2145,10 @@ <h2><dfn>BluetoothGATTCharacteristic</dfn></h2>
           See <a href="#notification-events"></a> for details of receiving notifications.
         </p>
         <ol>
+          <li>
+            If <code>this.uuid</code> is <a>blacklisted for reads</a>,
+            <a>reject</a> <var>promise</var> with a <a>SecurityError</a> and abort these steps.
+          </li>
           <li>
             Let <var>characteristic</var> be
             the GATT <a>Characteristic</a> that <code>this</code> represents.
@@ -2311,6 +2384,11 @@ <h2><dfn>BluetoothGATTDescriptor</dfn></h2>
           and run the following steps <a>in parallel</a>:
         </p>
         <ol>
+          <li>
+            If <code>this.uuid</code> is <a>blacklisted for reads</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             Let <var>descriptor</var> be the <a>Descriptor</a>
             that <code>this</code> represents.
@@ -2344,6 +2422,11 @@ <h2><dfn>BluetoothGATTDescriptor</dfn></h2>
           MUST  run the following steps:
         </p>
         <ol>
+          <li>
+            If <code>this.uuid</code> is <a>blacklisted for writes</a>,
+            return <a>a promise rejected with</a> a <a>SecurityError</a>
+            and abort these steps.
+          </li>
           <li>
             Let <var>descriptor</var> be the <a>Descriptor</a>
             that <code>this</code> represents.
@@ -2935,6 +3018,86 @@ <h2>Standardized UUIDs</h2>
       </section>
     </section>
 
+    <section>
+      <h2>The GATT Blacklist</h2>
+
+      <p>
+        This specification relies on a blacklist file in the
+        <a href="https://github.com/WebBluetoothCG/registries"
+           >https://github.com/WebBluetoothCG/registries</a> repository
+        to restrict the set of GATT attributes a website can access.
+      </p>
+
+      <p>
+        The result of <dfn>parsing the blacklist</dfn> at a URL <var>url</var>
+        is a map from <a>valid UUID</a>s to tokens, or an error,
+        produced by the following algorithm:
+      </p>
+      <ol>
+        <li>Fetch <var>url</var>, and let <var>contents</var> be its body, decoded as UTF-8.</li>
+        <li>Let <var>lines</var> be <var>contents</var> split on <code>'\n'</code>.</li>
+        <li>
+          Let <var>result</var> be an empty map.
+        </li>
+        <li>
+          For each <var>line</var> in <var>lines</var>, do the following sub-steps:
+          <ol>
+            <li>
+              If <var>line</var> is empty or its first character is <code>'#'</code>,
+              continue to the next line.
+            </li>
+            <li>
+              If <var>line</var> consists of just a <a>valid UUID</a>,
+              let <var>uuid</var> be that UUID and
+              let <var>token</var> be "<code>exclude</code>".
+            </li>
+            <li>
+              If <var>line</var> consists of a <a>valid UUID</a>, a space (U+0020),
+              and one of the tokens "<code>exclude-reads</code>" or "<code>exclude-writes</code>",
+              let <var>uuid</var> be that UUID and
+              let <var>token</var> be that token.
+            </li>
+            <li>
+              Otherwise, return an error and abort these steps.
+            </li>
+            <li>
+              If <var>uuid</var> is already in <var>result</var>,
+              return an error and abort these steps.
+            </li>
+            <li>
+              Add a mapping in <var>result</var> from <var>uuid</var> to <var>token</var>.
+            </li>
+          </ol>
+        </li>
+        <li>Return <var>result</var>.</li>
+      </ol>
+
+      <p>
+        The <dfn>GATT blacklist</dfn> is the result of <a>parsing the blacklist</a> at
+        <a href="https://github.com/WebBluetoothCG/registries/blob/master/gatt_blacklist.txt"
+           >https://github.com/WebBluetoothCG/registries/blob/master/gatt_blacklist.txt</a>.
+        The UA should re-fetch the blacklist periodically, but it's unspecified how often.
+      </p>
+
+      <p>
+        A <a>UUID</a> is <dfn>blacklisted</dfn> if either
+        the <a>GATT blacklist</a>'s value is an error,
+        or the UUID maps to "<code>exclude</code>" in the <a>GATT blacklist</a>.
+      </p>
+      <p>
+        A <a>UUID</a> is <dfn>blacklisted for reads</dfn> if either
+        the <a>GATT blacklist</a>'s value is an error,
+        or the UUID maps to either "<code>exclude</code>" or "<code>exclude-reads</code>"
+        in the <a>GATT blacklist</a>.
+      </p>
+      <p>
+        A <a>UUID</a> is <dfn>blacklisted for writes</dfn> if either
+        the <a>GATT blacklist</a>'s value is an error,
+        or the UUID maps to either "<code>exclude</code>" or "<code>exclude-writes</code>"
+        in the <a>GATT blacklist</a>.
+      </p>
+    </section>
+
     <section>
       <h2>Extensions to the Navigator Interface</h2>