SoK: The Constant Time Model

Billy Bob Brumley

Paper 2026/1242

SoK: The Constant Time Model

Billy Bob Brumley

, Rochester Institute of Technology

Abstract

Constant time programming patterns is the primary defense against timing attacks on cryptographic implementations, yet what "constant time" means varies across academia and industry. This work systematizes constant time models and their evolution, identifies a recurring gap between what models protect and what specifications assume, and distills an offensive methodology for discovering timing vulnerabilities that originate outside the cryptographic primitive boundary. Applying this methodology, we locate a specification-level vulnerability related to private key loading, and confirm the leak in both OpenSSL and BoringSSL. Counterintuitively, BoringSSL's per-observation signal is several orders of magnitude stronger than OpenSSL's, despite an explicitly stricter threat model.

Metadata

Available format(s): PDF
Category: Implementation
Publication info: Published elsewhere. WOOT 2026
Keywords: side channel analysis timing attacks leakage assessment elliptic curve cryptography OpenSSL BoringSSL
Contact author(s): bbbics @ rit edu
History: 2026-06-13: approved; 2026-06-11: received; See all versions
Short URL: https://ia.cr/2026/1242
License: CC BY-NC-SA

BibTeX

@misc{cryptoeprint:2026/1242,
      author = {Billy Bob Brumley},
      title = {{SoK}: The Constant Time Model},
      howpublished = {Cryptology {ePrint} Archive, Paper 2026/1242},
      year = {2026},
      url = {https://eprint.iacr.org/2026/1242}
}