Differential cryptanalysis is a method used to analyze the security of cryptographic algorithms, particularly block ciphers. It focuses on how differences in input can affect the differences in output, allowing attackers to uncover patterns and weaknesses in the encryption process. By studying how specific changes in plaintext lead to predictable changes in ciphertext, cryptanalysts can gain insights into the secret key used for encryption. This technique was first developed in the late 1980s by Eli Biham and Adi Shamir, who demonstrated its effectiveness against several popular ciphers. Differential cryptanalysis has since influenced the design of many modern encryption algorithms, prompting cryptographers to implement stronger defenses against such attacks.