Cryptography/Linear Cryptanalysis
Linear Cryptanalysis is using Linear mathematics (such as linear algebra) to break cryptosystems. This approach was strong against the now-obsolute cryptosystems based on Linear Shift Registers. Modern cryptosystems like AES and RSA use non-linear elements to prevent an attack based on linear cryptanalysis. In AES, the S-box provides non-linearity. In RSA, modular exponentiation provides non-linearity.