diff --git a/lib/util/keyutil.js b/lib/util/keyutil.js
new file mode 100644
index 00000000..e580cbe4
--- /dev/null
+++ b/lib/util/keyutil.js
@@ -0,0 +1,456 @@
+var util = require('util')
+
+var adb = require('adbkit')
+var Promise = require('bluebird')
+
+module.exports.parseKeyCharacterMap = function(stream) {
+  var resolver = Promise.defer()
+    , state = 'type_t'
+    , keymap = {
+        keys: []
+      }
+    , lastKey
+    , lastRule
+    , lastModifier
+    , lastBehavior
+
+  function fail(char, state) {
+    throw new Error(util.format(
+      'Unexpected character "%s" in state "%s"'
+    , char
+    , state
+    ))
+  }
+
+  function parse(char) {
+    switch (state) {
+      case 'comment_before_type_t':
+        if (char === '\n') {
+          state = 'type_t'
+          break
+        }
+        return true
+      case 'type_t':
+        if (char === '\n') {
+          return true
+        }
+        if (char === '#') {
+          state = 'comment_before_type_t'
+          return true
+        }
+        if (char === 'k') {
+          state = 'key_k'
+          return parse(char)
+        }
+        if (char === 't') {
+          state = 'type_y'
+          return true
+        }
+        return fail(char, state)
+      case 'type_y':
+        if (char === 'y') {
+          state = 'type_p'
+          return true
+        }
+        return fail(char, state)
+      case 'type_p':
+        if (char === 'p') {
+          state = 'type_e'
+          return true
+        }
+        return fail(char, state)
+      case 'type_e':
+        if (char === 'e') {
+          state = 'type_name_start'
+          keymap.type = ''
+          return true
+        }
+        return fail(char, state)
+      case 'type_name_start':
+        if (char === ' ') {
+          return true
+        }
+        if (char >= 'A' && char <= 'Z') {
+          keymap.type += char
+          state = 'type_name_continued'
+          return true
+        }
+        return fail(char, state)
+      case 'type_name_continued':
+        if (char === '\n') {
+          // Could have more of these, although it doesn't make much sense
+          state = 'type_t'
+          return true
+        }
+        if (char >= 'A' && char <= 'Z') {
+          keymap.type += char
+          return true
+        }
+        return fail(char, state)
+      case 'comment_before_key_k':
+        if (char === '\n') {
+          state = 'key_k'
+          break
+        }
+        return true
+      case 'key_k':
+        if (char === '\n') {
+          return true
+        }
+        if (char === '#') {
+          state = 'comment_before_key_k'
+          return true
+        }
+        if (char === 'k') {
+          state = 'key_e'
+          return true
+        }
+        return fail(char, state)
+      case 'key_e':
+        if (char === 'e') {
+          state = 'key_y'
+          return true
+        }
+        return fail(char, state)
+      case 'key_y':
+        if (char === 'y') {
+          state = 'key_name_start'
+          return true
+        }
+        return fail(char, state)
+      case 'key_name_start':
+        if (char === ' ') {
+          return true
+        }
+        if ((char >= '0' && char <= '9') ||
+            (char >= 'A' && char <= 'Z')) {
+          keymap.keys.push(lastKey = {
+            key: char
+          , rules: []
+          })
+          state = 'key_name_continued'
+          return true
+        }
+        return fail(char, state)
+      case 'key_name_continued':
+        if (char === ' ') {
+          state = 'key_start_block'
+          return true
+        }
+        if ((char >= '0' && char <= '9') ||
+            (char >= 'A' && char <= 'Z') ||
+            (char === '_')) {
+          lastKey.key += char
+          return true
+        }
+        return fail(char, state)
+      case 'key_start_block':
+        if (char === ' ') {
+          return true
+        }
+        if (char === '{') {
+          state = 'filter_name_start'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_name_start':
+        if (char === '\n' || char === '\t' || char === ' ') {
+          return true
+        }
+        if (char === '}') {
+          state = 'key_k'
+          return true
+        }
+        if (char >= 'a' && char <= 'z') {
+          lastKey.rules.push(lastRule = {
+            modifiers: [lastModifier = {
+              type: char
+            }]
+          , behaviors: []
+          })
+          state = 'filter_name_continued'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_name_continued':
+        if (char === ':') {
+          state = 'filter_behavior_start'
+          return true
+        }
+        if (char === ',') {
+          state = 'filter_name_or_start'
+          return true
+        }
+        if (char === '+') {
+          state = 'filter_name_and_start'
+          return true
+        }
+        if (char >= 'a' && char <= 'z') {
+          lastModifier.type += char
+          return true
+        }
+        return fail(char, state)
+      case 'filter_name_or_start':
+        if (char === ' ') {
+          return true
+        }
+        if (char >= 'a' && char <= 'z') {
+          lastKey.rules.push(lastRule = {
+            modifiers: [lastModifier = {
+              type: char
+            }]
+          , behaviors: lastRule.behaviors
+          })
+          state = 'filter_name_continued'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_name_and_start':
+        if (char === ' ') {
+          return true
+        }
+        if (char >= 'a' && char <= 'z') {
+          lastRule.modifiers.push(lastModifier = {
+            type: char
+          })
+          state = 'filter_name_continued'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_value':
+        if (char === '\\') {
+          state = 'filter_value_escape'
+          return true
+        }
+        if (char !== "'") {
+          lastRule.behaviors.push({
+            type: 'literal'
+          , value: char
+          })
+          state = 'filter_value_end'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_value_escape':
+        if (char === '\\' || char === '\'' || char === '"') {
+          lastRule.behaviors.push({
+            type: 'literal'
+          , value: char
+          })
+          state = 'filter_value_end'
+          return true
+        }
+        if (char === 'n') {
+          lastRule.behaviors.push({
+            type: 'literal'
+          , value: '\n'
+          })
+          state = 'filter_value_end'
+          return true
+        }
+        if (char === 't') {
+          lastRule.behaviors.push({
+            type: 'literal'
+          , value: '\t'
+          })
+          state = 'filter_value_end'
+          return true
+        }
+        if (char === 'u') {
+          state = 'filter_value_unicode_1'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_value_end':
+        if (char === '\'') {
+          state = 'filter_behavior_start'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_start':
+        if (char === '\n') {
+          state = 'filter_name_start'
+          return true
+        }
+        if (char === ' ') {
+          return true
+        }
+        if (char === "'") {
+          state = 'filter_value'
+          return true
+        }
+        if (char === 'n') {
+          state = 'filter_behavior_none_2'
+          return true
+        }
+        if (char === 'f') {
+          state = 'filter_behavior_fallback_2'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_fallback_2':
+        if (char === 'a') {
+          state = 'filter_behavior_fallback_3'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_fallback_3':
+        if (char === 'l') {
+          state = 'filter_behavior_fallback_4'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_fallback_4':
+        if (char === 'l') {
+          state = 'filter_behavior_fallback_5'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_fallback_5':
+        if (char === 'b') {
+          state = 'filter_behavior_fallback_6'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_fallback_6':
+        if (char === 'a') {
+          state = 'filter_behavior_fallback_7'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_fallback_7':
+        if (char === 'c') {
+          state = 'filter_behavior_fallback_8'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_fallback_8':
+        if (char === 'k') {
+          state = 'filter_behavior_fallback_key_start'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_fallback_key_start':
+        if (char === ' ') {
+          return true
+        }
+        if ((char >= '0' && char <= '9') ||
+            (char >= 'A' && char <= 'Z')) {
+          lastRule.behaviors.push(lastBehavior = {
+            type: 'fallback'
+          , key: char
+          })
+          state = 'filter_behavior_fallback_key_continued'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_fallback_key_continued':
+        if (char === ' ') {
+          state = 'filter_behavior_start'
+          return true
+        }
+        if (char === '\n') {
+          state = 'filter_name_start'
+          return true
+        }
+        if ((char >= '0' && char <= '9') ||
+            (char >= 'A' && char <= 'Z') ||
+            (char === '_')) {
+          lastBehavior.key += char
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_none_2':
+        if (char === 'o') {
+          state = 'filter_behavior_none_3'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_none_3':
+        if (char === 'n') {
+          state = 'filter_behavior_none_4'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_behavior_none_4':
+        if (char === 'e') {
+          lastRule.behaviors.push({
+            type: 'none'
+          })
+          state = 'filter_behavior_start'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_value_unicode_1':
+        if ((char >= '0' && char <= '9') ||
+            (char >= 'a' && char <= 'f')) {
+          lastRule.behaviors.push(lastBehavior = {
+            type: 'literal'
+          , value: parseInt(char, 16) << 12
+          })
+          state = 'filter_value_unicode_2'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_value_unicode_2':
+        if ((char >= '0' && char <= '9') ||
+            (char >= 'a' && char <= 'f')) {
+          lastBehavior.value += parseInt(char, 16) << 8
+          state = 'filter_value_unicode_3'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_value_unicode_3':
+        if ((char >= '0' && char <= '9') ||
+            (char >= 'a' && char <= 'f')) {
+          lastBehavior.value += parseInt(char, 16) << 4
+          state = 'filter_value_unicode_4'
+          return true
+        }
+        return fail(char, state)
+      case 'filter_value_unicode_4':
+        if ((char >= '0' && char <= '9') ||
+            (char >= 'a' && char <= 'f')) {
+          lastBehavior.value += parseInt(char, 16)
+          state = 'filter_value_end'
+          return true
+        }
+        return fail(char, state)
+      default:
+        throw new Error(util.format('Unexpected state "%s"', state))
+    }
+  }
+
+  function errorListener(err) {
+    resolver.reject(err)
+  }
+
+  function readableListener() {
+    var chunk = stream.read()
+      , i = 0
+      , l = chunk.length
+
+    try {
+      while (i < l) {
+        parse(String.fromCharCode(chunk[i++]))
+      }
+    }
+    catch (err) {
+      resolver.reject(err)
+    }
+  }
+
+  function endListener() {
+    resolver.resolve(keymap)
+  }
+
+  stream.on('error', errorListener)
+  stream.on('readable', readableListener)
+  stream.on('end', endListener)
+
+  return resolver.promise.finally(function() {
+    stream.removeListener('error', errorListener)
+    stream.removeListener('readable', readableListener)
+    stream.removeListener('end', endListener)
+  })
+}