RFC 5116

RFC 5116
Title	RFC 5116
Status	Informational
Published	January 2008
Authors	Hugo Krawczyk, John Viega
Pages	24
Category	Cryptography, API

RFC 5116 RFC 5116 is an informational specification that standardizes an Application Programming Interface for symmetric key encryption, designed to facilitate interoperable implementations among cryptographic libraries and applications. The document provides definitions and a minimal, well-specified API to support authenticated encryption with associated data across diverse platforms and runtimes. It was published by the Internet Engineering Task Force and authored by notable contributors in the field of cryptography.

Overview

RFC 5116 situates itself within the corpus of IETF work alongside other milestones such as Request for Comments, coordination by the Internet Engineering Task Force, and influences from standards developed by the National Institute of Standards and Technology, European Telecommunications Standards Institute, and the Internet Architecture Board. The API addresses needs raised in contexts like Transport Layer Security, IPsec, and protocols used by Mozilla Project, OpenSSL Project, and GnuPG developers. It intersects with research and deployments from institutions such as RSA Security, Google LLC, Microsoft Corporation, Apple Inc., Cisco Systems, and academia including Massachusetts Institute of Technology, Stanford University, and University of California, Berkeley. The RFC’s release followed contemporary discussions in venues like the USENIX, ACM Conference on Computer and Communications Security, and IEEE Symposium on Security and Privacy.

Terminology and Concepts

The document defines terms that echo work by authorities such as Claude Shannon, Whitfield Diffie, Martin Hellman, and Ron Rivest. It formalizes notions comparable to constructions in AES modes referenced by NIST Special Publication 800-38A, and authenticated encryption modes used in RFC 4309 and later in RFC 5116-adjacent deployments. The spec clarifies parameters including key sizes influenced by Federal Information Processing Standards, nonce and initialization vector usage discussed in IETF Working Group threads, and associated data patterns seen in S/MIME, Pretty Good Privacy, and OAuth flows. Concepts relate to ciphersuites employed in TLS 1.2 and influenced designs later used in TLS 1.3 implementations.

API Specification

RFC 5116 prescribes an API model that influenced libraries like OpenSSL Project, LibreSSL, BoringSSL, and language bindings for Python (programming language), Java (programming language), C (programming language), C++, Go (programming language), and Rust (programming language). The specification outlines functions for key creation, context initialization, encryption, decryption, and cleanup, analogous to interfaces in PKCS#11 and APIs from Microsoft Windows CryptoAPI and Apple Developer security frameworks. It specifies parameter semantics comparable to those used in IEEE 802.11 cryptographic modules and interoperable with token-based systems like Smart card, EMV, and HSMs from vendors such as Thales Group and Gemalto. The API design draws on engineering best practices evident in projects overseen by Apache Software Foundation and Linux Foundation communities, and patterns used in GitHub hosted repositories.

Security Considerations

The security guidance in RFC 5116 echoes warnings from seminal discussions involving Adrian Perrig, Ronald Rivest, and groups at Bell Labs and Xerox PARC. It emphasizes nonce misuse resistance, key management recommendations reflected in NIST SP 800-57, and authenticated encryption error handling consistent with advice from OWASP and incident analyses by CERT Coordination Center. Threat models reference attacks studied in papers presented at CRYPTO, Eurocrypt, ACM CCS, and NDSS. Guidance covers side-channel concerns highlighted by researchers from École Normale Supérieure, University of Cambridge, and ETH Zurich, and recommends integration practices compatible with FIPS 140-2 validated modules. It also reflects operational lessons from deployments by PayPal, Amazon Web Services, Facebook, and Stripe.

Implementation and Examples

Implementations and examples influenced by RFC 5116 appear in code bases maintained by OpenSSL Project, GnuTLS, LibreSSL, BoringSSL, and cryptographic libraries such as libsodium and Botan (software). Language-specific wrappers and examples were published in forums like Stack Overflow, educational materials from Coursera, edX, and tutorials by O’Reilly Media. Example integrations target protocols and software including SSH, DNSSEC, DANE, Signal Protocol, Matrix (protocol), and applications developed by Red Hat, Canonical (company), and Debian. Hardware-accelerated implementations take advantage of instructions from Intel Corporation and Advanced Micro Devices, and platforms such as ARM TrustZone and Intel SGX.

Adoption and Impact

RFC 5116 influenced API convergence across projects within ecosystems led by IETF, W3C, OWASP, and Cloud Security Alliance. Its principles can be traced in specifications and implementations adopted by Mozilla Foundation for Firefox, Google LLC for Chrome (web browser), and enterprise stacks from Oracle Corporation and IBM. The RFC’s role is visible in standards harmonization efforts with NIST, ETSI, and initiatives by ISO/IEC JTC 1. Academic citations appear in publications from Cornell University, Princeton University, and University of Oxford. The API contributed to interoperability improvements affecting secure messaging, online payments, and cloud services managed by Salesforce, Alibaba Group, and Tencent.

Category:Cryptography standards