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constant time

Code whose running time doesn't depend on the secret values it handles, so timing reveals nothing.

If an operation on a secret key or password takes longer for some values than others, an attacker measuring the time can infer the secret. Constant-time code deliberately performs the same work regardless of the secret data, closing that leak. Being "constant time over secrets" is a core security discipline for cryptographic code.

See also

  • constant-timeA coding discipline where execution timing never varies based on secret data.
  • constant-time equalA comparison that checks whether two secret values match without stopping early on the first difference.
  • blindingA trick where a secret operation is scrambled with a random value first, so its timing or power use reveals nothing about the secret.

Referenced by

blinding · ChaCha20-Poly1305 · constant-time · constant-time equal · CSPRNG