diff --git a/sha256_partitions.sh b/sha256_partitions.sh
new file mode 100755
index 0000000000..20426cae49
--- /dev/null
+++ b/sha256_partitions.sh
@@ -0,0 +1,50 @@
+#!/bin/sh
+
+# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This should be able to run outside the chroot on a standard Ubuntu system.
+
+BINFILE="$1"
+
+if [ -z "$BINFILE" ]; then
+  echo "usage: $0 .../path/to/file.bin"
+  exit 1
+fi
+
+parted "$BINFILE" unit s print | awk -v BF="$BINFILE" '
+/KERN-|ROOT-/ {
+  # Common things
+  printf "Partition " $1 " (" $NF "): "
+  start=substr($2, 0, length($2) - 1)  # strip trailing "s"
+}
+
+/KERN-/ {
+  cnt=substr($4, 0, length($4) - 1)
+  system("dd if=\"" BF "\" bs=512 skip=" start " count=" cnt \
+      " 2>/dev/null | openssl dgst -sha256 -binary | openssl base64")
+}
+
+/ROOT-/ {
+  # we have rootfs. find the filesystem size
+  "mktemp" | getline tmpfile
+  close("mktemp")
+  system("dd if=" BF " bs=512 skip=" start \
+      " count=400 of=" tmpfile " 2>/dev/null")  # copy superblock
+  blkcnt = 0
+  cmd = "dumpe2fs " tmpfile " 2>/dev/null | grep \"Block count\" | \
+      sed \"s/[^0-9]*//\""
+  cmd | getline blkcnt
+  close(cmd)
+  system("rm -f " tmpfile)
+  if (blkcnt > 0) {
+    blkcnt *= 8  # 4096 byte blocks -> 512 byte sectors
+    system("dd if=\"" BF "\" bs=512 skip=" start " count=" blkcnt \
+        " 2>/dev/null | openssl dgst -sha256 -binary | openssl base64")
+  } else {
+    print "invalid filesystem"
+  }
+}
+
+'