Combining instructions including an instruction that performs a sequence of transformations to isolate one transformation

摘要

The Advanced Encryption Standard (AES) is a symmetric block cipher that can encrypt and decrypt information. Encryption (cipher) performs a series of transformations (Shift Rows, Substitute Bytes, Mix Columns) using the secret key (cipher key) to transforms intelligible data referred to as “plaintext” into an unintelligible form referred to as “cipher text”. The transformations (Inverse Shift Rows, Inverse Substitute Bytes, Inverse Mix Columns) in the inverse cipher (decryption) are the inverse of the transformations in the cipher. Encryption and decryption is performed efficiently through the use of instructions that perform the series of transformations. Combinations of these instructions allow the isolation of the transformations (Shift Rows, Substitute Bytes, Mix Columns, Inverse Shift Rows, Inverse Substitute Bytes, Inverse Mix Columns) to be obtained.