pqcstatus
Algorithm

RC4: quantum risk, deadlines and replacements

Weakened by quantum

Broken stream cipher, prohibited in TLS.

At a glance

Quantum riskWeakened by quantum
Used forSymmetric encryption
Post-quantum algorithmNo

Positions and deadlines by authority

AuthorityPositionEffectiveScopeDetails
IETFDisallowedin forceall variants

Recommended replacements

Sources

  1. RFC 7465 — Prohibiting RC4 Cipher Suites · IETF

Catalog version 2026-09-28. Every position links to its primary source; draft documents are labelled as such.

Frequently Asked Questions

Is RC4 quantum-safe?

Partially. Grover’s algorithm reduces its effective security; larger variants remain adequate, while broken legacy variants must be retired now.

What should replace RC4?

AES.