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Utilavo

Symmetric Cipher Security Guide 2026: NIST Status by Algorithm

By Utilavo Editorial · Reviewed

A consolidated reference for the symmetric ciphers exposed by Utilavo's encryption tools. Status, key and block sizes, and deprecation dates are sourced directly from NIST SP 800-131A Rev 2 and SP 800-57 Part 1 Rev 5 so the recommendation column is auditable.

Methodology

Each algorithm row is populated from its current entry in NIST's transition guidance documents. The recommended column reflects the 2026 NIST guidance for new systems; deprecated_year reflects the year the algorithm was first formally disallowed for the relevant federal use case. No measurements are taken — this is a reference matrix, not a benchmark.

See the site-wide research methodology for shared test conditions and tooling.

Dataset

AlgorithmKey size (bits)Block size (bits)NIST statusDeprecated (year)Recommended for new systems
AES-128128128Approved (FIPS 197)—Yes
AES-192192128Approved (FIPS 197)—Yes
AES-256256128Approved (FIPS 197)—Yes (recommended for long-term confidentiality per SP 800-131A Rev 2)
Triple-DES (3-key TDEA)16864Disallowed for federal use after 2023 (SP 800-131A Rev 2)2023No
Triple-DES (2-key TDEA)11264Disallowed since 2015 (SP 800-131A Rev 1)2015No
DES5664Withdrawn — FIPS 46-3 withdrawn in 20052005No
RC440-2048N/A (stream)Never approved by NIST; prohibited in TLS by RFC 7465 (2015)2015No

Download raw data

The raw CSV contains every row in the table above plus any columns omitted from the rendered view.

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Citations

  1. NIST SP 800-131A Rev 2 — Transitioning the Use of Cryptographic Algorithms and Key Lengths (accessed )
  2. NIST SP 800-57 Part 1 Rev 5 — Recommendation for Key Management (accessed )
  3. FIPS 197 — Advanced Encryption Standard (AES) (accessed )
  4. RFC 7465 — Prohibiting RC4 Cipher Suites (accessed )