diff --git a/src/main/php/com/mongodb/Encrypted.class.php b/src/main/php/com/mongodb/Encrypted.class.php
new file mode 100755
index 0000000..247723a
--- /dev/null
+++ b/src/main/php/com/mongodb/Encrypted.class.php
@@ -0,0 +1,16 @@
+<?php namespace com\mongodb;
+
+class Encrypted {
+  private $ciphertext;
+
+  public function __construct($ciphertext) {
+    $this->ciphertext= (string)$ciphertext;
+  }
+
+  /** @return int */
+  public function length() { return strlen($this->ciphertext); }
+
+  /** @return string */
+  public function ciphertext() { return $this->ciphertext; }
+
+}
\ No newline at end of file
diff --git a/src/main/php/com/mongodb/io/BSON.class.php b/src/main/php/com/mongodb/io/BSON.class.php
index ff5147a..9e78b65 100755
--- a/src/main/php/com/mongodb/io/BSON.class.php
+++ b/src/main/php/com/mongodb/io/BSON.class.php
@@ -1,7 +1,7 @@
 <?php namespace com\mongodb\io;
 
 use Traversable, StdClass;
-use com\mongodb\{ObjectId, Timestamp, Regex, Int64, Code, Decimal128, MinKey, MaxKey};
+use com\mongodb\{ObjectId, Timestamp, Regex, Int64, Code, Decimal128, MinKey, MaxKey, Encrypted};
 use lang\{FormatException, IllegalArgumentException};
 use util\{Bytes, Date, TimeZone, UUID};
 
@@ -58,6 +58,8 @@ public function bytes($name, $value) {
       return "\xff".$name."\x00";
     } else if ($value instanceof MaxKey) {
       return "\x7f".$name."\x00";
+    } else if ($value instanceof Encrypted) {
+      return "\x05".$name."\x00".pack('Vc', $value->length(), 6).$value->ciphertext();
     } else if ($value instanceof Traversable || $value instanceof StdClass) {
       return "\x03".$name."\x00".$this->sections($value);
     } else if (is_string($value)) {
@@ -132,6 +134,7 @@ public function value($name, $bytes, &$offset) {
       switch ($binary['subtype']) {
         case 0: case 2: return $value;
         case 3: case 4: return new UUID($value);
+        case 6: return new Encrypted($value);
         default: throw new FormatException('Cannot handle binary subtype '.$binary['subtype']);
       }
     } else if ("\x07" === $kind) {    // ObjectId
diff --git a/src/test/php/com/mongodb/unittest/BSONTest.class.php b/src/test/php/com/mongodb/unittest/BSONTest.class.php
index 9d881e0..461b9eb 100755
--- a/src/test/php/com/mongodb/unittest/BSONTest.class.php
+++ b/src/test/php/com/mongodb/unittest/BSONTest.class.php
@@ -1,7 +1,7 @@
 <?php namespace com\mongodb\unittest;
 
 use com\mongodb\io\BSON;
-use com\mongodb\{Code, Decimal128, Document, Int64, MaxKey, MinKey, ObjectId, Regex, Timestamp};
+use com\mongodb\{Code, Decimal128, Document, Int64, MaxKey, MinKey, ObjectId, Regex, Timestamp, Encrypted};
 use lang\{FormatException, IllegalArgumentException};
 use test\{Assert, Expect, Test, Values};
 use util\{Bytes, Date, UUID};
@@ -60,6 +60,7 @@ private function values() {
 
     // Special types
     yield [new Bytes('abc'), "\x05test\x00\x03\x00\x00\x00\x00abc"];
+    yield [new Encrypted('ciphertext'), "\x05test\x00\x0a\x00\x00\x00\x06ciphertext"];
     yield [new Date('2020-08-03 17:41 +0200'), "\x09test\x00\xe0\xae\xfb\xb4\x73\x01\x00\x00"];
     yield [new Date('1969-08-03 17:41 +0200'), "\x09test\x00\xe0\x3e\xbd\xf9\xfc\xff\xff\xff"];
     yield [new Timestamp(1596543032, 1), "\x11test\x00\x01\x00\x00\x00\x38\x50\x29\x5f"];