diff --git a/tools/releasetools/validate_target_files.py b/tools/releasetools/validate_target_files.py
new file mode 100755
index 0000000..1dd3159
--- /dev/null
+++ b/tools/releasetools/validate_target_files.py
@@ -0,0 +1,127 @@
+#!/usr/bin/env python
+
+# Copyright (C) 2017 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Validate a given (signed) target_files.zip.
+
+It performs checks to ensure the integrity of the input zip.
+ - It verifies the file consistency between the ones in IMAGES/system.img (read
+   via IMAGES/system.map) and the ones under unpacked folder of SYSTEM/. The
+   same check also applies to the vendor image if present.
+"""
+
+import common
+import logging
+import os.path
+import sparse_img
+import sys
+
+
+def _GetImage(which, tmpdir):
+  assert which in ('system', 'vendor')
+
+  path = os.path.join(tmpdir, 'IMAGES', which + '.img')
+  mappath = os.path.join(tmpdir, 'IMAGES', which + '.map')
+
+  # Map file must exist (allowed to be empty).
+  assert os.path.exists(path) and os.path.exists(mappath)
+
+  clobbered_blocks = '0'
+  return sparse_img.SparseImage(path, mappath, clobbered_blocks)
+
+
+def ValidateFileConsistency(input_zip, input_tmp):
+  """Compare the files from image files and unpacked folders."""
+
+  def RoundUpTo4K(value):
+    rounded_up = value + 4095
+    return rounded_up - (rounded_up % 4096)
+
+  def CheckAllFiles(which):
+    logging.info('Checking %s image.', which)
+    image = _GetImage(which, input_tmp)
+    prefix = '/' + which
+    for entry in image.file_map:
+      if not entry.startswith(prefix):
+        continue
+
+      # Read the blocks that the file resides. Note that it will contain the
+      # bytes past the file length, which is expected to be padded with '\0's.
+      ranges = image.file_map[entry]
+      blocks_sha1 = image.RangeSha1(ranges)
+
+      # The filename under unpacked directory, such as SYSTEM/bin/sh.
+      unpacked_name = os.path.join(
+          input_tmp, which.upper(), entry[(len(prefix) + 1):])
+      with open(unpacked_name) as f:
+        file_data = f.read()
+      file_size = len(file_data)
+      file_size_rounded_up = RoundUpTo4K(file_size)
+      file_data += '\0' * (file_size_rounded_up - file_size)
+      file_sha1 = common.File(entry, file_data).sha1
+
+      assert blocks_sha1 == file_sha1, \
+          'file: %s, range: %s, blocks_sha1: %s, file_sha1: %s' % (
+              entry, ranges, blocks_sha1, file_sha1)
+
+  logging.info('Validating file consistency.')
+
+  # Verify IMAGES/system.img.
+  CheckAllFiles('system')
+
+  # Verify IMAGES/vendor.img if applicable.
+  if 'VENDOR/' in input_zip.namelist():
+    CheckAllFiles('vendor')
+
+  # Not checking IMAGES/system_other.img since it doesn't have the map file.
+
+
+def main(argv):
+  def option_handler():
+    return True
+
+  args = common.ParseOptions(
+      argv, __doc__, extra_opts="",
+      extra_long_opts=[],
+      extra_option_handler=option_handler)
+
+  if len(args) != 1:
+    common.Usage(__doc__)
+    sys.exit(1)
+
+  logging_format = '%(asctime)s - %(filename)s - %(levelname)-8s: %(message)s'
+  date_format = '%Y/%m/%d %H:%M:%S'
+  logging.basicConfig(level=logging.INFO, format=logging_format,
+                      datefmt=date_format)
+
+  logging.info("Unzipping the input target_files.zip: %s", args[0])
+  input_tmp, input_zip = common.UnzipTemp(args[0])
+
+  ValidateFileConsistency(input_zip, input_tmp)
+
+  # TODO: Check if the OTA keys have been properly updated (the ones on /system,
+  # in recovery image).
+
+  # TODO(b/35411009): Verify the contents in /system/bin/install-recovery.sh.
+
+  logging.info("Done.")
+
+
+if __name__ == '__main__':
+  try:
+    main(sys.argv[1:])
+  finally:
+    common.Cleanup()