LEHMAN Test

is a test used to quickly determine if a number n is prime.  Prime numbers are essential in cryptography.

LFSR (Linear Feedback Shift Register)

is a simple mechanism for generating a sequence of binary bits.

Linear Cryptanalysis

is a type of cryptanalytic attack against symmetric algorithms. It uses linear approximations to try to find out the secret key. It was designed by MATSUI in 1993.
It was the first successful computer experiment for breaking DES. It requires 243 known plaintext-ciphertext pairs generated under the same key.

Linear Feedback Shift Register

see LFSR