AES Encryption

The Advanced Encryption Standard (AES) is one of the most secure and widely used symmetric encryption algorithms in the world. It operates on blocks of data and, in this tool, supports keys of 128, 192, or 256 bits.

• Passphrase: This is your secret password. It is not used directly as the encryption key but as a basis for deriving a secure key.
• Key Derivation Function (KDF): Functions like PBKDF2 and EvpKDF transform your passphrase into a strong cryptographic key. They use a Salt and Iterations to make brute-force attacks more difficult.
• Salt: A random value added to the passphrase before key derivation. It prevents two identical passwords from resulting in the same key, making dictionary and rainbow table attacks harder. It is highly recommended.
• Iterations: The number of times the hash algorithm is applied. The higher the number, the slower and more secure the key derivation process.
• Operation Mode and Initialization Vector (IV): The mode (e.g., CBC) defines how data blocks are encrypted. To ensure that encrypting the same message with the same password results in different ciphertexts, an IV (a random number) is used. It is combined with the first data block, and its effect propagates. The IV is not secret and is returned along with the ciphertext, as it is essential for decryption.
• Padding: Ensures that the last data block has the correct size for the algorithm. PKCS7 is the most common.

The final result is a string in Base64 or Hexadecimal containing the ciphertext, ready to be stored or transmitted securely. To decrypt, you will need to use the exact same parameters (passphrase, salt, IV, mode, etc.).