Arduino Uno water turbidity gauge has been successfully designed and manufactured. This tool is made using LDR as sensor and led as a light source to measure the water turbidity value and Arduino Uno for data processing. The existence of this tool is already familiar and comfortable to find. However, the price is relatively higher to make this tool is only owned by certain circles only. Nephelometric Method is a method of measuring the turbidity of water by passing a light source on water so that the intensity of light reflected by the substances causing turbidity can be known. With the use of led as a light source and photodiode as a light detector, and combined with processing using Arduino Uno then the voltage obtained from the LDR sensor in the form of analog data is processed into digital data and can be displayed in the LCD.

The security and confidentiality of information becomes an important factor in communication, the use of cryptography can be a powerful way of securing the information, IDEA (International Data Encryption Algorithm) and WAKE (Word Auto Key Encryption) are some modern symmetric cryptography algorithms with encryption and decryption function are much faster than the asymmetric cryptographic algorithm, with the combination experiment IDEA and WAKE it probable to produce highly secret ciphertext and it hopes to take a very long time for cryptanalyst to decrypt the information without knowing the key of the encryption process.