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SESK: Stuff Everyone Should Know · sesk.info/secplus-aes-key-sizes

Which key lengths does the Advanced Encryption Standard (AES) support?

128, 192 and 256 bits, with a fixed 128-bit block.

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  1. 56, 112 and 168 bits
  2. 512, 1024 and 2048 bits
  3. 128, 192 and 256 bits ✔

Why: AES is a symmetric cipher, so the same key encrypts and decrypts. Longer keys are harder to brute force, and every version works on 128-bit blocks.

Huh, didn't know that: AES comes from the Rijndael family of ciphers, and the number in AES-128, AES-192 and AES-256 is the key length in bits.

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What form of digital payment does Superman avoid? Crypto-nite currency.
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References

Answer: 128, 192 and 256 bits. AES is a symmetric cipher, so the same key encrypts and decrypts. Longer keys are harder to brute force, and every version works on 128-bit blocks.

  1. FIPS 197, Advanced Encryption Standard (AES) nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.197-upd1.pdf
    AES algorithm is capable of using cryptographic keys of 128, 192, and 256 bits to encrypt and decrypt data in blocks of 128 bits
    Checked 2026-10-10.
  2. FIPS 197, Advanced Encryption Standard (AES) nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.197-upd1.pdf
    Rijndael family are specifed in this Standard: AES-128, AES-192, and AES-256
    Checked 2026-10-10.

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