Differential Cryptanalysis is an #Analytic Attacks against Feistel Cipher Structure# by comparing the input (plaintext) and output (ciphertext) differences. It is focus on the non-linearity of the cipher especially the S-boxes.
The mechanic revolves around the probability \(p\) for input or output. If instances of some higher probability input or output pairs could be found, then we can infer to the subkey that was in used in the round. Then we proceed to iterate the process for many rounds with decreasing probabilities.
Using this method, we could crack Data Encryption Standard (DES) with \(2^{47}\) chosen plaintexts.