Move Symmetric Encryption Key generation into its own method

Test update for future class based encryption system without static
methods

www/admin/class_test.encryption.php

@@ -92,6 +92,13 @@ try {
 	print "Error: " . $e->getMessage() . "<br>";
 }
 
+// echo "<hr>";
+// $key = CreateKey::generateRandomKey();
+// $se = new SymmetricEncryption($key);
+// $string = "I a some deep secret";
+// $encrypted = $se->encrypt($string);
+// $decrypted = $se->decrypt($encrypted);
+
 print "</body></html>";
 
 // __END__

www/lib/CoreLibs/Security/SymmetricEncryption.php

@@ -22,15 +22,12 @@ use SodiumException;
 class SymmetricEncryption
 {
 	/**
-	 * Encrypt a message
+	 * create key and check validity
 	 *
-	 * @param  string $message Message to encrypt
+	 * @param  string $key The key from which the binary key will be created
-	 * @param  string $key     Encryption key (as hex string)
+	 * @return string      Binary key string
-	 * @return string
-	 * @throws \Exception
-	 * @throws \RangeException
 	 */
-	public static function encrypt(string $message, string $key): string
+	public static function createKey(string $key): string
 	{
 		try {
 			$key = CreateKey::hex2bin($key);
@@ -43,6 +40,21 @@ class SymmetricEncryption
 					. 'SODIUM_CRYPTO_SECRETBOX_KEYBYTES bytes long).'
 			);
 		}
+		return $key;
+	}
+
+	/**
+	 * Encrypt a message
+	 *
+	 * @param  string $message Message to encrypt
+	 * @param  string $key     Encryption key (as hex string)
+	 * @return string
+	 * @throws \Exception
+	 * @throws \RangeException
+	 */
+	public static function encrypt(string $message, string $key): string
+	{
+		$key = self::createKey($key);
 		$nonce = random_bytes(SODIUM_CRYPTO_SECRETBOX_NONCEBYTES);
 
 		$cipher = base64_encode(
@@ -68,11 +80,7 @@ class SymmetricEncryption
 	 */
 	public static function decrypt(string $encrypted, string $key): string
 	{
-		try {
+		$key = self::createKey($key);
-			$key = CreateKey::hex2bin($key);
-		} catch (SodiumException $e) {
-			throw new \Exception('Invalid hex 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');