Using Drive Syncrypt is very easy

During the first run of the app you will be asked to select a Google account. This is the account the app will use to have access to Google Drive. After that, you need to grant access to Drive Syncrypt to view and manage your Google Drive files. Touch the 'OK' button in the Google's dialog and you are ready to proceed with the setup of sync entries.

You need to setup one or more sync entries in 3 easy steps and the app will automatically keep in sync your files with Google Drive.


Touch the '+' button in the action bar to start the setup wizard. Follow these steps:


Step 1. Select local directory

This is the local directory in your device's external storage (SD) that you want to keep in sync with Google Drive.

Please note that due to limitation of access of external removable SD card on Android KitKat (4.4+) you have to select a directory in your devices storage.

For your safety the root directory of the SD can't be used for sync. You have to select a sub directory. Touching the '+' button you can create a new directory.

Then touch the 'NEXT' button.


Step 2. Select Google Drive directory

Obviously, this is the directory in Google Drive that it will be in sync with the local directory you selected in previous step.

The root directory in Google Drive can be selected only in Premium version. Touching the '+' button you can create a new directory.

Select the directory and touch the 'NEXT' button.


Step 3. Select synchronization parameters.

In this step you may select the different sync methods for the specific sync entry.


Select if the sync point will be active or inactive. Inactive sync entries are skipped during the sync process. You may easily activate or deactivate the sync entry from app's main screen at any time.


Sync type

You may use 3 different sync methods:

  1. Two-way: Changes in both local and Drive directories will be propagated bi-directionally. Conflicts are automatically resolved depending on file modification time.
  2. Upload only: Local directory will be mirrored to Drive directory. Any change in local directory will be pushed to Drive directory but changes in Drive directory will be lost.
  3. Download only: Drive directory will be mirrored to local directory. Any change in Drive directory will be pushed to local directory but changes in local directory will be lost


Instant upload

If you select instant upload, a service will monitor for file changes in the local directory (and sub-directories). Changes in local directory will trigger the sync process immediately.

You may use this option in two-way or upload only sync methods.


Encrypt files on Drive

If you enable encryption (upload only method) local files will be encrypted before upload in Google Drive. Drive Syncyrpt uses the strong AES encryption method with 256 bit key. The key is derived from your password that you may set in app's settings (please see below). The password itself is encrypted with AES and saved in app's private data.

Using encryption, you protect your data and you are sure that no one can access them without your password.

IMPORTANT: If you forget your passwords any access to your data will be impossible. So, please make sure that you will remember it.

Drive Syncrypt will add an extension (.enc) to your files and will upload them to Google Drive. You may download them in your PC and use DSCrypto tool to decrypt them. Also, if you use Drive Syncyrpt from another device and use the same Google Drive directory and same password, the app will automatically decrypt the files after the download.


Exclude files pattern

Using patterns allows you to exclude specific files from sync procedures. You may use multiple patterns separating by comma. Wildcards may be used. '*' for multiple characters and '?' for single character. For example if you want to exclude all jpg files enter the following:


If you also want to exclude all files that filename start from 'Screenshot':


Or combine the 2 above:

*.png, Screenshot*


Touch the 'FINISH' button.

A new sync entry will be created. An info card will be displayed for each sync entry under the main card which displays information about your Google account.

Use long touch to select a sync entry. Then, you may touch the 'Delete' button to delete the sync entry. Of course, this will delete only the sync entry and not your files.

On demand you may use the 'Refresh' button on action bar to initiate a manual sync.



Sync Frequency

Select the sync frequency of periodic sync among predefined values (never, 30 minutes, 1 hour, 2 hours, 6 hours, 1 day)


Google Account

Select your Google account to be used for sync with Drive



Set the password for file encryption


Notify on sync

Enable to receive detailed notification during the sync procedure


Release on sync complete

Check to release notification on sync complete


Cellular Data

Check to be able to sync when using mobile data (be careful for additional costs from your carrier)


While charging only

Check to allow sync when your device is attached to a charger


Skip on low battery

Check to forbid sync when the device is low on battery (<= 15%)


Sync procedure

Drive Syncrypt implements a robust sync procedure based on Android's sync mechanism.

Periodic syncs will be initiated combined with other syncs of your Google's account to preserve power and resources.

You may also control Drive Syncrypt sync from your device's Settings -> Accounts -> Google -> (Your account)


In-app purchase

You may upgrade to Premium version using Google's in-app purchases. Just select purchase from app's menu.

Premium version offers:

  • More than one sync entries
  • Ability to sync with Google Drive root folder
  • Ad free content


Basic knowledge of Linux is required to be able to build the kernel. We will also need a modern Linux box (preferably).


Basic Setup

First, we need to setup a directory in which we will clone the kernel and initramfs repositories. In this guide, we will setup them in /tmp but you can do it in any directory you want.


In a terminal we run:


mkdir /tmp/semaphore
cd /tmp/semaphore


Then we clone the basic kernel repository:

git clone


Finally we clone the initramfs repository:

git clone


OK, first step done. We got the code. Now we have to do some preparation and compile it.



I prefer to use a mini ugly script to compile the kernel and pack it. It's located in the root of the kernel tree (/tmp/semaphore/samsung-kernel-aries/


We open this file with an editor of our choice (I prefer vi) and edit:

1) The two lines with the 'make' command, changing the CROSS_COMPILE= option. We need to set the path from the cross compiler toolchain. I use the one that it's included in CM9 repository.

2) The line starting with the 'find' command, changing the kernel source directory and destination directory of the modules location. This is into the initramfs directory. In our example it's /tmp/semaphore/ics-ramdisk/ics_combo/files/modules


The Semaphore's kernel configuration is located in the file config_sema in the root kernel directory. So, we need to copy this file as .config:


cp config_sema .config


Then we run this command to start the Linux kernel configuration utility (again change the CROSS_COMPILE according to your toolchain directory):

make CROSS_COMPILE=/kernels/semaphore_cap/android/android/system/prebuilt/linux-x86/toolchain/arm-eabi-4.4.3/bin/arm-eabi- ARCH=arm menuconfig


We go to 'General Setup' section and we change the 'Initramfs source files' option to /tmp/semaphore/ics-ramdisk/ics_combo/

We also need to change the next 2 options User ID and Group ID to whatever uid and gid we are logged in in the Linux box. In my case is 500,500. We exit and save the configuration.



Now we are ready to build the kernel!


We just run:



We wait few minutes (time depends on the machine) and hopefully the compilation will end.


The script will produce 2 files.

1) /tmp/semaphore/samsung-kernel-aries/arch/arm/boot/zImage 

2) /tmp/semaphore/ics-ramdisk/cwm/


These are the 2 known files that we can flash via Heimdal or CWM respectively.

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