What AES Does
The Advanced Encryption Standard, or AES, is the most widely used symmetric cipher. It is a block cipher, meaning it transforms data in fixed size chunks of sixteen bytes using a secret key of one hundred twenty eight, one hundred ninety two, or two hundred fifty six bits.
Internally AES runs several rounds of substitution, permutation, and mixing. Each round scrambles the block so that flipping one input bit changes roughly half the output bits. This property, called the avalanche effect, makes the relationship between plaintext and ciphertext look random to anyone without the key.
Why a Block Cipher Is Not Enough
AES by itself only encrypts one block. Real messages are longer, so you need a mode of operation that defines how blocks chain together. Choosing AES does not finish the job.
- AES is trusted and fast, often accelerated in hardware.
- Pick a strong key length, with two hundred fifty six bits common for long term data.
- Always pair AES with a secure mode and never encrypt each block independently.
Key idea
AES is a strong fixed size block cipher, but it must be combined with a secure mode of operation so that long messages stay protected.