diff --git a/apps/encryption/lib/crypto/encryption.php b/apps/encryption/lib/crypto/encryption.php
index 1bd6af2eca..d2925e1b6b 100644
--- a/apps/encryption/lib/crypto/encryption.php
+++ b/apps/encryption/lib/crypto/encryption.php
@@ -84,6 +84,9 @@ class Encryption implements IEncryptionModule {
 	/** @var EncryptAll */
 	private $encryptAll;
 
+	/** @var  bool */
+	private $useMasterPassword;
+
 	/**
 	 *
 	 * @param Crypt $crypt
@@ -105,6 +108,7 @@ class Encryption implements IEncryptionModule {
 		$this->encryptAll = $encryptAll;
 		$this->logger = $logger;
 		$this->l = $il10n;
+		$this->useMasterPassword = $util->isMasterKeyEnabled();
 	}
 
 	/**
@@ -193,23 +197,26 @@ class Encryption implements IEncryptionModule {
 				$this->writeCache = '';
 			}
 			$publicKeys = array();
-			foreach ($this->accessList['users'] as $uid) {
-				try {
-					$publicKeys[$uid] = $this->keyManager->getPublicKey($uid);
-				} catch (PublicKeyMissingException $e) {
-					$this->logger->warning(
-						'no public key found for user "{uid}", user will not be able to read the file',
-						['app' => 'encryption', 'uid' => $uid]
-					);
-					// if the public key of the owner is missing we should fail
-					if ($uid === $this->user) {
-						throw $e;
+			if ($this->useMasterPassword === true) {
+				$publicKeys[$this->keyManager->getMasterKeyId()] = $this->keyManager->getPublicMasterKey();
+			} else {
+				foreach ($this->accessList['users'] as $uid) {
+					try {
+						$publicKeys[$uid] = $this->keyManager->getPublicKey($uid);
+					} catch (PublicKeyMissingException $e) {
+						$this->logger->warning(
+							'no public key found for user "{uid}", user will not be able to read the file',
+							['app' => 'encryption', 'uid' => $uid]
+						);
+						// if the public key of the owner is missing we should fail
+						if ($uid === $this->user) {
+							throw $e;
+						}
 					}
 				}
 			}
 
 			$publicKeys = $this->keyManager->addSystemKeys($this->accessList, $publicKeys, $this->user);
-
 			$encryptedKeyfiles = $this->crypt->multiKeyEncrypt($this->fileKey, $publicKeys);
 			$this->keyManager->setAllFileKeys($this->path, $encryptedKeyfiles);
 		}
@@ -318,8 +325,12 @@ class Encryption implements IEncryptionModule {
 		if (!empty($fileKey)) {
 
 			$publicKeys = array();
-			foreach ($accessList['users'] as $user) {
-				$publicKeys[$user] = $this->keyManager->getPublicKey($user);
+			if ($this->useMasterPassword === true) {
+				$publicKeys[$this->keyManager->getMasterKeyId()] = $this->keyManager->getPublicMasterKey();
+			} else {
+				foreach ($accessList['users'] as $user) {
+					$publicKeys[$user] = $this->keyManager->getPublicKey($user);
+				}
 			}
 
 			$publicKeys = $this->keyManager->addSystemKeys($accessList, $publicKeys, $uid);
diff --git a/apps/encryption/lib/keymanager.php b/apps/encryption/lib/keymanager.php
index 6c793e5964..c450722887 100644
--- a/apps/encryption/lib/keymanager.php
+++ b/apps/encryption/lib/keymanager.php
@@ -54,6 +54,10 @@ class KeyManager {
 	 * @var string
 	 */
 	private $publicShareKeyId;
+	/**
+	 * @var string
+	 */
+	private $masterKeyId;
 	/**
 	 * @var string UserID
 	 */
@@ -131,10 +135,20 @@ class KeyManager {
 			$this->config->setAppValue('encryption', 'publicShareKeyId', $this->publicShareKeyId);
 		}
 
+		$this->masterKeyId = $this->config->getAppValue('encryption',
+			'masterKeyId');
+		if (empty($this->masterKeyId)) {
+			$this->masterKeyId = 'master_' . substr(md5(time()), 0, 8);
+			$this->config->setAppValue('encryption', 'masterKeyId', $this->masterKeyId);
+		}
+
 		$this->keyId = $userSession && $userSession->isLoggedIn() ? $userSession->getUser()->getUID() : false;
 		$this->log = $log;
 	}
 
+	/**
+	 * check if key pair for public link shares exists, if not we create one
+	 */
 	public function validateShareKey() {
 		$shareKey = $this->getPublicShareKey();
 		if (empty($shareKey)) {
@@ -152,6 +166,26 @@ class KeyManager {
 		}
 	}
 
+	/**
+	 * check if a key pair for the master key exists, if not we create one
+	 */
+	public function validateMasterKey() {
+		$masterKey = $this->getPublicMasterKey();
+		if (empty($masterKey)) {
+			$keyPair = $this->crypt->createKeyPair();
+
+			// Save public key
+			$this->keyStorage->setSystemUserKey(
+				$this->masterKeyId . '.publicKey', $keyPair['publicKey'],
+				Encryption::ID);
+
+			// Encrypt private key with system password
+			$encryptedKey = $this->crypt->encryptPrivateKey($keyPair['privateKey'], $this->getMasterKeyPassword(), $this->masterKeyId);
+			$header = $this->crypt->generateHeader();
+			$this->setSystemPrivateKey($this->masterKeyId, $header . $encryptedKey);
+		}
+	}
+
 	/**
 	 * @return bool
 	 */
@@ -304,8 +338,15 @@ class KeyManager {
 
 		$this->session->setStatus(Session::INIT_EXECUTED);
 
+
 		try {
-			$privateKey = $this->getPrivateKey($uid);
+			if($this->util->isMasterKeyEnabled()) {
+				$uid = $this->getMasterKeyId();
+				$passPhrase = $this->getMasterKeyPassword();
+				$privateKey = $this->getSystemPrivateKey($uid);
+			} else {
+				$privateKey = $this->getPrivateKey($uid);
+			}
 			$privateKey = $this->crypt->decryptPrivateKey($privateKey, $passPhrase, $uid);
 		} catch (PrivateKeyMissingException $e) {
 			return false;
@@ -345,6 +386,10 @@ class KeyManager {
 	public function getFileKey($path, $uid) {
 		$encryptedFileKey = $this->keyStorage->getFileKey($path, $this->fileKeyId, Encryption::ID);
 
+		if ($this->util->isMasterKeyEnabled()) {
+			$uid = $this->getMasterKeyId();
+		}
+
 		if (is_null($uid)) {
 			$uid = $this->getPublicShareKeyId();
 			$shareKey = $this->getShareKey($path, $uid);
@@ -566,4 +611,37 @@ class KeyManager {
 
 		return $publicKeys;
 	}
+
+	/**
+	 * get master key password
+	 *
+	 * @return string
+	 * @throws \Exception
+	 */
+	protected function getMasterKeyPassword() {
+		$password = $this->config->getSystemValue('secret');
+		if (empty($password)){
+			throw new \Exception('Can not get secret from ownCloud instance');
+		}
+
+		return $password;
+	}
+
+	/**
+	 * return master key id
+	 *
+	 * @return string
+	 */
+	public function getMasterKeyId() {
+		return $this->masterKeyId;
+	}
+
+	/**
+	 * get public master key
+	 *
+	 * @return string
+	 */
+	public function getPublicMasterKey() {
+		return $this->keyStorage->getSystemUserKey($this->masterKeyId . '.publicKey', Encryption::ID);
+	}
 }
diff --git a/apps/encryption/lib/users/setup.php b/apps/encryption/lib/users/setup.php
index 433ea824c9..d4f7c37454 100644
--- a/apps/encryption/lib/users/setup.php
+++ b/apps/encryption/lib/users/setup.php
@@ -84,6 +84,7 @@ class Setup {
 	 */
 	public function setupServerSide($uid, $password) {
 		$this->keyManager->validateShareKey();
+		$this->keyManager->validateMasterKey();
 		// Check if user already has keys
 		if (!$this->keyManager->userHasKeys($uid)) {
 			return $this->keyManager->storeKeyPair($uid, $password,
diff --git a/apps/encryption/lib/util.php b/apps/encryption/lib/util.php
index fbedc5d607..e9f916eff3 100644
--- a/apps/encryption/lib/util.php
+++ b/apps/encryption/lib/util.php
@@ -101,6 +101,16 @@ class Util {
 		return ($recoveryMode === '1');
 	}
 
+	/**
+	 * check if master key is enabled
+	 *
+	 * @return bool
+	 */
+	public function isMasterKeyEnabled() {
+		$userMasterKey = $this->config->getAppValue('encryption', 'useMasterKey', '0');
+		return ($userMasterKey === '1');
+	}
+
 	/**
 	 * @param $enabled
 	 * @return bool
diff --git a/apps/encryption/tests/lib/KeyManagerTest.php b/apps/encryption/tests/lib/KeyManagerTest.php
index 71b00cf254..8f1da623ef 100644
--- a/apps/encryption/tests/lib/KeyManagerTest.php
+++ b/apps/encryption/tests/lib/KeyManagerTest.php
@@ -27,6 +27,7 @@ namespace OCA\Encryption\Tests;
 
 
 use OCA\Encryption\KeyManager;
+use OCA\Encryption\Session;
 use Test\TestCase;
 
 class KeyManagerTest extends TestCase {
@@ -237,24 +238,62 @@ class KeyManagerTest extends TestCase {
 
 	}
 
+	/**
+	 * @dataProvider dataTestInit
+	 *
+	 * @param bool $useMasterKey
+	 */
+	public function testInit($useMasterKey) {
 
-	public function testInit() {
-		$this->keyStorageMock->expects($this->any())
-			->method('getUserKey')
-			->with($this->equalTo($this->userId), $this->equalTo('privateKey'))
-			->willReturn('privateKey');
-		$this->cryptMock->expects($this->any())
-			->method('decryptPrivateKey')
-			->with($this->equalTo('privateKey'), $this->equalTo('pass'))
-			->willReturn('decryptedPrivateKey');
+		$instance = $this->getMockBuilder('OCA\Encryption\KeyManager')
+			->setConstructorArgs(
+				[
+					$this->keyStorageMock,
+					$this->cryptMock,
+					$this->configMock,
+					$this->userMock,
+					$this->sessionMock,
+					$this->logMock,
+					$this->utilMock
+				]
+			)->setMethods(['getMasterKeyId', 'getMasterKeyPassword', 'getSystemPrivateKey', 'getPrivateKey'])
+			->getMock();
 
+		$this->utilMock->expects($this->once())->method('isMasterKeyEnabled')
+			->willReturn($useMasterKey);
 
-		$this->assertTrue(
-			$this->instance->init($this->userId, 'pass')
-		);
+		$this->sessionMock->expects($this->at(0))->method('setStatus')
+			->with(Session::INIT_EXECUTED);
 
+		$instance->expects($this->any())->method('getMasterKeyId')->willReturn('masterKeyId');
+		$instance->expects($this->any())->method('getMasterKeyPassword')->willReturn('masterKeyPassword');
+		$instance->expects($this->any())->method('getSystemPrivateKey')->with('masterKeyId')->willReturn('privateMasterKey');
+		$instance->expects($this->any())->method('getPrivateKey')->with($this->userId)->willReturn('privateUserKey');
+
+		if($useMasterKey) {
+			$this->cryptMock->expects($this->once())->method('decryptPrivateKey')
+				->with('privateMasterKey', 'masterKeyPassword', 'masterKeyId')
+				->willReturn('key');
+		} else {
+			$this->cryptMock->expects($this->once())->method('decryptPrivateKey')
+				->with('privateUserKey', 'pass', $this->userId)
+				->willReturn('key');
+		}
+
+		$this->sessionMock->expects($this->once())->method('setPrivateKey')
+			->with('key');
+
+		$this->assertTrue($instance->init($this->userId, 'pass'));
 	}
 
+	public function dataTestInit() {
+		return [
+			[true],
+			[false]
+		];
+	}
+
+
 	public function testSetRecoveryKey() {
 		$this->keyStorageMock->expects($this->exactly(2))
 			->method('setSystemUserKey')
@@ -401,5 +440,92 @@ class KeyManagerTest extends TestCase {
 		);
 	}
 
+	public function testGetMasterKeyId() {
+		$this->assertSame('systemKeyId', $this->instance->getMasterKeyId());
+	}
+
+	public function testGetPublicMasterKey() {
+		$this->keyStorageMock->expects($this->once())->method('getSystemUserKey')
+			->with('systemKeyId.publicKey', \OCA\Encryption\Crypto\Encryption::ID)
+			->willReturn(true);
+
+		$this->assertTrue(
+			$this->instance->getPublicMasterKey()
+		);
+	}
+
+	public function testGetMasterKeyPassword() {
+		$this->configMock->expects($this->once())->method('getSystemValue')->with('secret')
+			->willReturn('password');
+
+		$this->assertSame('password',
+			$this->invokePrivate($this->instance, 'getMasterKeyPassword', [])
+		);
+	}
+
+	/**
+	 * @expectedException \Exception
+	 */
+	public function testGetMasterKeyPasswordException() {
+		$this->configMock->expects($this->once())->method('getSystemValue')->with('secret')
+			->willReturn('');
+
+		$this->invokePrivate($this->instance, 'getMasterKeyPassword', []);
+	}
+
+	/**
+	 * @dataProvider dataTestValidateMasterKey
+	 *
+	 * @param $masterKey
+	 */
+	public function testValidateMasterKey($masterKey) {
+
+		/** @var \OCA\Encryption\KeyManager | \PHPUnit_Framework_MockObject_MockObject $instance */
+		$instance = $this->getMockBuilder('OCA\Encryption\KeyManager')
+			->setConstructorArgs(
+				[
+					$this->keyStorageMock,
+					$this->cryptMock,
+					$this->configMock,
+					$this->userMock,
+					$this->sessionMock,
+					$this->logMock,
+					$this->utilMock
+				]
+			)->setMethods(['getPublicMasterKey', 'setSystemPrivateKey', 'getMasterKeyPassword'])
+			->getMock();
+
+		$instance->expects($this->once())->method('getPublicMasterKey')
+			->willReturn($masterKey);
+
+		$instance->expects($this->any())->method('getMasterKeyPassword')->willReturn('masterKeyPassword');
+		$this->cryptMock->expects($this->any())->method('generateHeader')->willReturn('header');
+
+		if(empty($masterKey)) {
+			$this->cryptMock->expects($this->once())->method('createKeyPair')
+				->willReturn(['publicKey' => 'public', 'privateKey' => 'private']);
+			$this->keyStorageMock->expects($this->once())->method('setSystemUserKey')
+				->with('systemKeyId.publicKey', 'public', \OCA\Encryption\Crypto\Encryption::ID);
+			$this->cryptMock->expects($this->once())->method('encryptPrivateKey')
+				->with('private', 'masterKeyPassword', 'systemKeyId')
+				->willReturn('EncryptedKey');
+			$instance->expects($this->once())->method('setSystemPrivateKey')
+				->with('systemKeyId', 'headerEncryptedKey');
+		} else {
+			$this->cryptMock->expects($this->never())->method('createKeyPair');
+			$this->keyStorageMock->expects($this->never())->method('setSystemUserKey');
+			$this->cryptMock->expects($this->never())->method('encryptPrivateKey');
+			$instance->expects($this->never())->method('setSystemPrivateKey');
+		}
+
+		$instance->validateMasterKey();
+	}
+
+	public function dataTestValidateMasterKey() {
+		return [
+			['masterKey'],
+			['']
+		];
+	}
 
 }
diff --git a/apps/encryption/tests/lib/UtilTest.php b/apps/encryption/tests/lib/UtilTest.php
index e75e8ea36b..9988ff93f4 100644
--- a/apps/encryption/tests/lib/UtilTest.php
+++ b/apps/encryption/tests/lib/UtilTest.php
@@ -132,4 +132,25 @@ class UtilTest extends TestCase {
 		return $default ?: null;
 	}
 
+	/**
+	 * @dataProvider dataTestIsMasterKeyEnabled
+	 *
+	 * @param string $value
+	 * @param bool $expect
+	 */
+	public function testIsMasterKeyEnabled($value, $expect) {
+		$this->configMock->expects($this->once())->method('getAppValue')
+			->with('encryption', 'useMasterKey', '0')->willReturn($value);
+		$this->assertSame($expect,
+			$this->instance->isMasterKeyEnabled()
+		);
+	}
+
+	public function dataTestIsMasterKeyEnabled() {
+		return [
+			['0', false],
+			['1', true]
+		];
+	}
+
 }
diff --git a/apps/encryption/tests/lib/users/SetupTest.php b/apps/encryption/tests/lib/users/SetupTest.php
index e6936c5c12..bca3ff58b0 100644
--- a/apps/encryption/tests/lib/users/SetupTest.php
+++ b/apps/encryption/tests/lib/users/SetupTest.php
@@ -43,6 +43,8 @@ class SetupTest extends TestCase {
 	private $instance;
 
 	public function testSetupServerSide() {
+		$this->keyManagerMock->expects($this->exactly(2))->method('validateShareKey');
+		$this->keyManagerMock->expects($this->exactly(2))->method('validateMasterKey');
 		$this->keyManagerMock->expects($this->exactly(2))
 			->method('userHasKeys')
 			->with('admin')