diff --git a/CheckEncryption.cpp b/CheckEncryption.cpp
new file mode 100644
index 0000000..ffa3698
--- /dev/null
+++ b/CheckEncryption.cpp
@@ -0,0 +1,149 @@
+/*
+ * 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.
+ */
+
+#include "CheckEncryption.h"
+#include "FileDeviceUtils.h"
+#include "Utils.h"
+#include "VolumeManager.h"
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+#include <cutils/iosched_policy.h>
+#include <private/android_filesystem_config.h>
+
+#include <sstream>
+
+#include <sys/resource.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+#include <assert.h>
+#include <fcntl.h>
+#include <linux/fs.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+using android::base::unique_fd;
+
+using android::base::ReadFileToString;
+using android::base::WriteStringToFile;
+
+namespace android {
+namespace vold {
+
+constexpr uint32_t max_extents = 32;
+constexpr size_t bytecount = 8;
+constexpr int repeats = 256;
+
+bool check_file(const std::string& needle) {
+    LOG(DEBUG) << "checkEncryption check_file: " << needle;
+    auto haystack = android::vold::BlockDeviceForPath(needle);
+    if (haystack.empty()) {
+        LOG(ERROR) << "Failed to find device for path: " << needle;
+        return false;
+    }
+
+    std::string randombytes;
+    if (ReadRandomBytes(bytecount, randombytes) != 0) {
+        LOG(ERROR) << "Failed to read random bytes";
+        return false;
+    }
+    std::string randomhex;
+    StrToHex(randombytes, randomhex);
+    std::ostringstream os;
+    for (int i = 0; i < repeats; i++) os << randomhex;
+    auto towrite = os.str();
+
+    if (access(needle.c_str(), F_OK) == 0) {
+        if (unlink(needle.c_str()) != 0) {
+            PLOG(ERROR) << "Failed to unlink " << needle;
+            return false;
+        }
+    }
+    LOG(DEBUG) << "Writing to " << needle;
+    if (!WriteStringToFile(towrite, needle)) {
+        PLOG(ERROR) << "Failed to write " << needle;
+        return false;
+    }
+    sync();
+
+    unique_fd haystack_fd(open(haystack.c_str(), O_RDONLY | O_CLOEXEC));
+    if (haystack_fd.get() == -1) {
+        PLOG(ERROR) << "Failed to open " << haystack;
+        return false;
+    }
+
+    auto fiemap = PathFiemap(needle, max_extents);
+
+    std::string area;
+    for (uint32_t i = 0; i < fiemap->fm_mapped_extents; i++) {
+        auto xt = &(fiemap->fm_extents[i]);
+        LOG(DEBUG) << "Extent " << i << " at " << xt->fe_physical << " length " << xt->fe_length;
+        if (lseek64(haystack_fd.get(), xt->fe_physical, SEEK_SET) == -1) {
+            PLOG(ERROR) << "Failed lseek";
+            return false;
+        }
+        auto toread = xt->fe_length;
+        while (toread > 0) {
+            char buf[BUFSIZ];
+            size_t wlen =
+                static_cast<size_t>(std::min(static_cast<typeof(toread)>(sizeof(buf)), toread));
+            auto l = read(haystack_fd.get(), buf, wlen);
+            if (l < 1) {
+                PLOG(ERROR) << "Failed read";
+                if (errno != EINTR) {
+                    return false;
+                }
+            }
+            area.append(buf, l);
+            toread -= l;
+        }
+    }
+
+    LOG(DEBUG) << "Searching " << area.size() << " bytes of " << needle;
+    LOG(DEBUG) << "First position of blob: " << area.find(randomhex);
+    return true;
+}
+
+int CheckEncryption(const std::string& path) {
+    auto deNeedle(path);
+    deNeedle += "/misc";
+    if (android::vold::PrepareDir(deNeedle, 01771, AID_SYSTEM, AID_MISC)) {
+        return -1;
+    }
+    deNeedle += "/vold";
+    if (android::vold::PrepareDir(deNeedle, 0700, AID_ROOT, AID_ROOT)) {
+        return -1;
+    }
+    deNeedle += "/checkEncryption";
+
+    auto neNeedle(path);
+    neNeedle += "/unencrypted/checkEncryption";
+
+    check_file(deNeedle);
+    check_file(neNeedle);
+
+    return 0;
+}
+
+}  // namespace vold
+}  // namespace android