Advanced Encryption Standard (AES) is a symmetric block cipher that encrypts and decrypts data in 128-bit blocks using 128, 192, or 256-bit keys. It is the most widely used encryption algorithm for securing data at rest and in transit.
Inputs
Block Cipher Mode: Determines how blocks of plaintext are processed.
Padding: How to pad plaintext that is not a multiple of 16 bytes. Only applicable for ECB and CBC modes.
Key: The symmetric key in hexadecimal. Must be 16 bytes (128-bit), 24 bytes (192-bit), or 32 bytes (256-bit).
IV: Initialization Vector in hexadecimal. 16 bytes for CBC/CFB/OFB, 12 bytes recommended for GCM.
Data: The plaintext (encrypt) or ciphertext (decrypt) in HEX or ASCII format.
Tips
AES-128 is sufficient for most applications. AES-256 provides a higher security margin.
ECB mode reveals patterns in plaintext — avoid it for anything beyond a single block.
GCM mode provides both encryption and authentication in one pass.
For payment/HSM environments, CBC with zero IV is commonly used for key encryption.