Encrypt decrypt string

EncryptDecrypt.cs

  public static byte[] iv;
	public byte[] DoEncryptionString(string strText)
	{ 
	   var secretKey = GetKeyFromKeyStore();
		Cipher cipher = Cipher.GetInstance("AES/GCM/NoPadding");
		cipher.Init(Javax.Crypto.CipherMode.EncryptMode, secretKey);

		iv = cipher.GetIV(); 
		var encryption = cipher.DoFinal(System.Text.Encoding.UTF8.GetBytes(strText)); 
		return encryption;
	}

	public string DoDecryptionString(byte[] strEncrypted)
	{ 
		var secretKey = GetKeyFromKeyStore();
		Cipher cipher = Cipher.GetInstance("AES/GCM/NoPadding");
		Javax.Crypto.Spec.GCMParameterSpec spec = new Javax.Crypto.Spec.GCMParameterSpec(128, iv);
		cipher.Init(Javax.Crypto.CipherMode.DecryptMode, secretKey, spec); 
		byte[] decodedData = cipher.DoFinal(strEncrypted);
		var data = System.Text.Encoding.UTF8.GetString(decodedData);
		return data;  
	}