AES-Key-Dependent-Dynamic-S-Box

The provided code snippet is from a Java class called AES2 that implements the Advanced Encryption Standard (AES) algorithm. Here's a breakdown of the code: Key Initialization:

Springer Link

AES Encryption/Decryption in Java

Features:

• Implements the Advanced Encryption Standard (AES) for encryption and decryption.
• Supports 128-bit keys.
• Utilizes a pre-computed S-Box for non-linear data substitution.
• Performs various round-based operations for enhanced security.

Functionality:

• Key Initialization:
  • Takes a byte array as the key.
  • Sets internal variables like state matrix, expanded key, and round parameters.
• Encryption/Decryption:
  • cipher: Encrypts input data (2D byte array) through multiple rounds of:
    • Adding round key.
    • Substituting bytes using the S-Box.
    • Shifting rows of the state matrix.
    • Mixing columns within the state matrix.
  • decipher: Decrypts data using the inverse operations of encryption.
• S-Box Operations:
  • subBytes and invSubBytes: Perform byte substitution based on the pre-defined S-Box table.
  • (Commented) "dynamic S-Box" section offers an alternative approach (not used by default).
• Other Methods:
  • expandKey: Generates the expanded key from the initial key.
  • shiftRows, mixColumns, invShiftRows, invMixColumnas: Handle specific byte manipulations within the state matrix during encryption/decryption rounds.

Benefits:

• Provides secure and efficient AES implementation for 128-bit data.
• Offers clear separation of key initialization, encryption/decryption, and internal operations.
• Includes commented sections for further exploration and understanding.

Note:

This is a concise overview for a README file. For detailed instructions and code explanations, please refer to the complete source code.