diff --git a/src/Security/SymmetricEncryption.php b/src/Security/SymmetricEncryption.php
index 8062fb5..c12f4b3 100644
--- a/src/Security/SymmetricEncryption.php
+++ b/src/Security/SymmetricEncryption.php
@@ -21,66 +21,82 @@ use SodiumException;
 
 class SymmetricEncryption
 {
+	/** @var SymmetricEncryption self instance */
+	private static SymmetricEncryption $instance;
+
+	/** @var string bin hex key */
+	private string $key = '';
+
+	/**
+	 * init class
+	 * if key not passed, key must be set with createKey
+	 *
+	 * @param  string|null|null $key
+	 */
+	public function __construct(
+		string|null $key = null
+	) {
+		if ($key != null) {
+			$this->setKey($key);
+		}
+	}
+
+	/**
+	 * Returns the singleton self object.
+	 * For function wrapper use
+	 *
+	 * @return SymmetricEncryption object
+	 */
+	public static function getInstance(string|null $key = null): self
+	{
+		if (empty(self::$instance)) {
+			self::$instance = new self($key);
+		}
+		return self::$instance;
+	}
+
+	/* ************************************************************************
+	 * MARK: PRIVATE
+	 * *************************************************************************/
+
 	/**
 	 * create key and check validity
 	 *
 	 * @param  string $key The key from which the binary key will be created
 	 * @return string      Binary key string
 	 */
-	public static function createKey(string $key): string
+	private function createKey(string $key): string
 	{
 		try {
 			$key = CreateKey::hex2bin($key);
 		} catch (SodiumException $e) {
-			throw new \UnexpectedValueException('Invalid hex key');
+			throw new \UnexpectedValueException('Invalid hex key: ' . $e->getMessage());
 		}
 		if (mb_strlen($key, '8bit') !== SODIUM_CRYPTO_SECRETBOX_KEYBYTES) {
 			throw new \RangeException(
 				'Key is not the correct size (must be '
-					. 'SODIUM_CRYPTO_SECRETBOX_KEYBYTES bytes long).'
+					. SODIUM_CRYPTO_SECRETBOX_KEYBYTES . ' bytes long).'
 			);
 		}
 		return $key;
 	}
 
 	/**
-	 * Encrypt a message
+	 * Decryption call
 	 *
-	 * @param  string $message Message to encrypt
-	 * @param  string $key     Encryption key (as hex string)
-	 * @return string
-	 * @throws \Exception
+	 * @param  string  $encrypted Text to decrypt
+	 * @param  ?string $key       Mandatory encryption key, will throw exception if empty
+	 * @return string             Plain text
 	 * @throws \RangeException
+	 * @throws \UnexpectedValueException
+	 * @throws \UnexpectedValueException
 	 */
-	public static function encrypt(string $message, string $key): string
+	private function decryptData(string $encrypted, ?string $key): string
 	{
-		$key = self::createKey($key);
-		$nonce = random_bytes(SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
-
-		$cipher = base64_encode(
-			$nonce
-			. sodium_crypto_secretbox(
-				$message,
-				$nonce,
-				$key
-			)
-		);
-		sodium_memzero($message);
-		sodium_memzero($key);
-		return $cipher;
-	}
-
-	/**
-	 * Decrypt a message
-	 *
-	 * @param  string $encrypted Message encrypted with safeEncrypt()
-	 * @param  string $key       Encryption key (as hex string)
-	 * @return string
-	 * @throws \Exception
-	 */
-	public static function decrypt(string $encrypted, string $key): string
-	{
-		$key = self::createKey($key);
+		if (empty($key)) {
+			throw new \UnexpectedValueException('Key not set');
+		}
+		$key = $this->createKey($key);
 		$decoded = base64_decode($encrypted);
 		$nonce = mb_substr($decoded, 0, SODIUM_CRYPTO_SECRETBOX_NONCEBYTES, '8bit');
 		$ciphertext = mb_substr($decoded, SODIUM_CRYPTO_SECRETBOX_NONCEBYTES, null, '8bit');
@@ -93,7 +109,7 @@ class SymmetricEncryption
 				$key
 			);
 		} catch (SodiumException $e) {
-			throw new \UnexpectedValueException('Invalid ciphertext (too short)');
+			throw new \UnexpectedValueException('Decipher message failed: ' . $e->getMessage());
 		}
 		if (!is_string($plain)) {
 			throw new \UnexpectedValueException('Invalid Key');
@@ -102,6 +118,117 @@ class SymmetricEncryption
 		sodium_memzero($key);
 		return $plain;
 	}
+
+	/**
+	 * Encrypt a message
+	 *
+	 * @param  string  $message Message to encrypt
+	 * @param  ?string $key     Mandatory encryption key, will throw exception if empty
+	 * @return string
+	 * @throws \Exception
+	 * @throws \RangeException
+	 */
+	private function encryptData(string $message, ?string $key): string
+	{
+		if (empty($this->key) || $key === null) {
+			throw new \UnexpectedValueException('Key not set');
+		}
+		$key = $this->createKey($key);
+		$nonce = random_bytes(SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
+		try {
+			$cipher = base64_encode(
+				$nonce
+				. sodium_crypto_secretbox(
+					$message,
+					$nonce,
+					$key,
+				)
+			);
+		} catch (SodiumException $e) {
+			throw new \UnexpectedValueException("Create encrypted message failed: " . $e->getMessage());
+		}
+		sodium_memzero($message);
+		sodium_memzero($key);
+		return $cipher;
+	}
+
+	/* ************************************************************************
+	 * MARK: PUBLIC
+	 * *************************************************************************/
+
+
+	/**
+	 * set a new key for encryption
+	 *
+	 * @param  string $key
+	 * @return void
+	 */
+	public function setKey(string $key)
+	{
+		if (empty($key)) {
+			throw new \UnexpectedValueException('Key cannot be empty');
+		}
+		$this->key = $key;
+	}
+
+	/**
+	 * Decrypt a message
+	 * static version
+	 *
+	 * @param  string $encrypted Message encrypted with safeEncrypt()
+	 * @param  string $key       Encryption key (as hex string)
+	 * @return string
+	 * @throws \Exception
+	 * @throws \RangeException
+	 * @throws \UnexpectedValueException
+	 * @throws \UnexpectedValueException
+	 */
+	public static function decryptKey(string $encrypted, string $key): string
+	{
+		return self::getInstance()->decryptData($encrypted, $key);
+	}
+
+	/**
+	 * Decrypt a message
+	 *
+	 * @param  string $encrypted Message encrypted with safeEncrypt()
+	 * @return string
+	 * @throws \RangeException
+	 * @throws \UnexpectedValueException
+	 * @throws \UnexpectedValueException
+	 */
+	public function decrypt(string $encrypted): string
+	{
+		return $this->decryptData($encrypted, $this->key);
+	}
+
+	/**
+	 * Encrypt a message
+	 * static version
+	 *
+	 * @param  string $message Message to encrypt
+	 * @param  string $key     Encryption key (as hex string)
+	 * @return string
+	 * @throws \Exception
+	 * @throws \RangeException
+	 */
+	public static function encryptKey(string $message, string $key): string
+	{
+		return self::getInstance()->encryptData($message, $key);
+	}
+
+	/**
+	 * Encrypt a message
+	 *
+	 * @param  string $message Message to encrypt
+	 * @return string
+	 * @throws \Exception
+	 * @throws \RangeException
+	 */
+	public function encrypt(string $message): string
+	{
+		return $this->encryptData($message, $this->key);
+	}
 }
 
 // __END__
diff --git a/test/phpunit/Security/CoreLibsSecuritySymmetricEncryptionTest.php b/test/phpunit/Security/CoreLibsSecuritySymmetricEncryptionTest.php
index 33a2f45..d3f502a 100644
--- a/test/phpunit/Security/CoreLibsSecuritySymmetricEncryptionTest.php
+++ b/test/phpunit/Security/CoreLibsSecuritySymmetricEncryptionTest.php
@@ -46,12 +46,34 @@ final class CoreLibsSecuritySymmetricEncryptionTest extends TestCase
 	public function testEncryptDecryptSuccess(string $input, string $expected): void
 	{
 		$key = CreateKey::generateRandomKey();
-		$encrypted = SymmetricEncryption::encrypt($input, $key);
-		$decrypted = SymmetricEncryption::decrypt($encrypted, $key);
+
+		// test class
+		$crypt = new SymmetricEncryption($key);
+		$encrypted = $crypt->encrypt($input);
+		$decrypted = $crypt->decrypt($encrypted);
+		$this->assertEquals(
+			$expected,
+			$decrypted,
+			'Class call',
+		);
+
+		// test indirect
+		$encrypted = SymmetricEncryption::getInstance($key)->encrypt($input);
+		$decrypted = SymmetricEncryption::getInstance($key)->decrypt($encrypted);
+		$this->assertEquals(
+			$expected,
+			$decrypted,
+			'Class Instance call',
+		);
+
+		// test static
+		$encrypted = SymmetricEncryption::encryptKey($input, $key);
+		$decrypted = SymmetricEncryption::decryptKey($encrypted, $key);
 
 		$this->assertEquals(
 			$expected,
-			$decrypted
+			$decrypted,
+			'Static call',
 		);
 	}
 
@@ -86,10 +108,24 @@ final class CoreLibsSecuritySymmetricEncryptionTest extends TestCase
 	public function testEncryptFailed(string $input, string $exception_message): void
 	{
 		$key = CreateKey::generateRandomKey();
-		$encrypted = SymmetricEncryption::encrypt($input, $key);
 		$wrong_key = CreateKey::generateRandomKey();
+
+		// wrong key in class call
+		$crypt = new SymmetricEncryption($key);
+		$encrypted = $crypt->encrypt($input);
 		$this->expectExceptionMessage($exception_message);
-		SymmetricEncryption::decrypt($encrypted, $wrong_key);
+		$crypt->setKey($key);
+		$crypt->decrypt($encrypted);
+
+		// class instance
+		$encrypted = SymmetricEncryption::getInstance($key)->encrypt($input);
+		$this->expectExceptionMessage($exception_message);
+		SymmetricEncryption::getInstance($wrong_key)->decrypt($encrypted);
+
+		// class static
+		$encrypted = SymmetricEncryption::encryptKey($input, $key);
+		$this->expectExceptionMessage($exception_message);
+		SymmetricEncryption::decryptKey($encrypted, $wrong_key);
 	}
 
 	/**
@@ -107,7 +143,6 @@ final class CoreLibsSecuritySymmetricEncryptionTest extends TestCase
 			'too short hex key' => [
 				'key' => '1cabd5cba9e042f12522f4ff2de5c31d233b',
 				'excpetion_message' => 'Key is not the correct size (must be '
-					. 'SODIUM_CRYPTO_SECRETBOX_KEYBYTES bytes long).'
 			],
 		];
 	}
@@ -126,13 +161,33 @@ final class CoreLibsSecuritySymmetricEncryptionTest extends TestCase
 	 */
 	public function testWrongKey(string $key, string $exception_message): void
 	{
-		$this->expectExceptionMessage($exception_message);
-		SymmetricEncryption::encrypt('test', $key);
-		// we must encrypt valid thing first so we can fail with the wrong kjey
 		$enc_key = CreateKey::generateRandomKey();
-		$encrypted = SymmetricEncryption::encrypt('test', $enc_key);
+
+		// class
+		$crypt = new SymmetricEncryption($key);
 		$this->expectExceptionMessage($exception_message);
-		SymmetricEncryption::decrypt($encrypted, $key);
+		$crypt->encrypt('test');
+		$crypt->setKey($enc_key);
+		$encrypted = $crypt->encrypt('test');
+		$this->expectExceptionMessage($exception_message);
+		$crypt->setKey($key);
+		$crypt->decrypt($encrypted);
+
+		// class instance
+		$this->expectExceptionMessage($exception_message);
+		SymmetricEncryption::getInstance($key)->encrypt('test');
+		// we must encrypt valid thing first so we can fail with the wrong key
+		$encrypted = SymmetricEncryption::getInstance($enc_key)->encrypt('test');
+		$this->expectExceptionMessage($exception_message);
+		SymmetricEncryption::getInstance($key)->decrypt($encrypted);
+
+		// class static
+		$this->expectExceptionMessage($exception_message);
+		SymmetricEncryption::encryptKey('test', $key);
+		// we must encrypt valid thing first so we can fail with the wrong key
+		$encrypted = SymmetricEncryption::encryptKey('test', $enc_key);
+		$this->expectExceptionMessage($exception_message);
+		SymmetricEncryption::decryptKey($encrypted, $key);
 	}
 
 	/**
@@ -145,7 +200,7 @@ final class CoreLibsSecuritySymmetricEncryptionTest extends TestCase
 		return [
 			'too short ciphertext' => [
 				'input' => 'short',
-				'exception_message' => 'Invalid ciphertext (too short)'
+				'exception_message' => 'Decipher message failed: '
 			],
 		];
 	}
@@ -164,8 +219,18 @@ final class CoreLibsSecuritySymmetricEncryptionTest extends TestCase
 	public function testWrongCiphertext(string $input, string $exception_message): void
 	{
 		$key = CreateKey::generateRandomKey();
+		// class
+		$crypt = new SymmetricEncryption($key);
 		$this->expectExceptionMessage($exception_message);
-		SymmetricEncryption::decrypt($input, $key);
+		$crypt->decrypt($input);
+
+		// class instance
+		$this->expectExceptionMessage($exception_message);
+		SymmetricEncryption::getInstance($key)->decrypt($input);
+
+		// class static
+		$this->expectExceptionMessage($exception_message);
+		SymmetricEncryption::decryptKey($input, $key);
 	}
 }