Linear Cryptanalysis is a method used to analyze and break symmetric key ciphers. It relies on finding linear approximations between the plaintext, ciphertext, and key bits. By exploiting these linear relationships, attackers can gain information about the secret key, making it easier to decrypt messages without needing to try every possible key. This technique was first introduced by Mitsuru Matsui in the early 1990s. It is particularly effective against block ciphers, such as DES and AES, where the structure allows for the identification of patterns. Linear cryptanalysis can significantly reduce the number of required ciphertexts for successful key recovery.