Encrypt and decrypt (and also random generator)

Simple and fast cryptation method, useful for internal use within a program (data storage). However, for serious code breakers, this cryptation is no match.

Key Mul:

Key Add:

Key Seed:

Decrypted text using characters: TestData
Encrypted text using numbers (character codes):

Generated random number sequence:

Due to execution time in JavaScript, max 4096 characters are allowed.