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What key does symmetric encryption use to encrypt and decrypt?

It uses the same secret key for encryption and decryption.

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  1. The same secret key ✔
  2. A public key only
  3. No keys at all

Why: Symmetric cryptography uses one shared secret for an operation and its inverse. Both communicating parties therefore need a secure way to obtain that secret.

Huh, didn't know that: AES is a widely used symmetric encryption algorithm.

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The symmetric key likes matching outfits for encryption and decryption.
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References

Answer: The same secret key. Symmetric cryptography uses one shared secret for an operation and its inverse. Both communicating parties therefore need a secure way to obtain that secret.

  1. NIST CSRC Symmetric Cryptography Glossary csrc.nist.gov/glossary/term/Symmetric_Cryptography
    A cryptographic algorithm that uses the same secret key for its operation and, if applicable, for reversing the effects
    Checked 2026-10-10.

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