The Data Encryption Standard (DES) is a symmetric-key algorithm used for data encryption. It is based on the two fundamental concepts of substitution (or confusion) and transposition (or diffusion). Encryption and decryption take the same algorithm. It makes it very easy to program a reverse function and change the order of the key.
Sometimes, researchers need to collect supporting and identification data like location, device type, operating system, etc. along with the responses. Such data can be stored in custom variables and used to define the path of the survey. They are passed along with the survey URL. Researchers can also filter responses based on the custom variables.
QuestionPro uses the DES algorithm to encrypt custom variables passed along with the survey URL. They are decrypted and saved as part of the response.
You'll need to enter an eight-character key that will be used to encrypt and decrypt the custom variables.
DES method uses a 56-bit key to encrypt the data. So, there can be 2^56 possibilities of keys. It would take a very long time to find the correct key using a brute-force attack.
For more details and to learn how to set up this feature, refer our help file on DES encryption.