RFC 2617

RFC 2617
Title	RFC 2617
Type	Request for Comments
Status	Informational
Authors	"R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee"
Published	"June 1999"
Relates	"HTTP/1.1, RFC 2068, RFC 2616"

RFC 2617

Background and Purpose

RFC 2617 specifies authentication schemes for the Hypertext Transfer Protocol and updates prior work in the context of the Internet Engineering Task Force. It formalizes mechanisms that integrate with Hypertext Transfer Protocol implementations and aligns with contemporaneous standards from the IETF and working groups associated with Internet Engineering Task Force activities. The document situates HTTP authentication alongside other Internet protocols developed at institutions such as MIT, CERN, and organizations like the World Wide Web Consortium and addresses interoperability concerns encountered during the evolution of HTTP deployments.

Authentication Schemes (Basic and Digest)

RFC 2617 defines two primary authentication schemes: "Basic" and "Digest". The Basic scheme uses a straightforward credential encoding compatible with implementations referenced in RFC 2068 and other IETF specifications, while the Digest scheme builds on challenge–response ideas similar to earlier work in Kerberos and challenge-response systems used by projects at Stanford University and Xerox PARC. Digest incorporates concepts influenced by message-digest algorithms standardized by bodies such as the National Institute of Standards and Technology and formal hash functions like those designed under initiatives involving Ronald Rivest and the RSA Data Security, Inc. community. Both schemes were designed to interoperate with HTTP infrastructure deployed at entities including Netscape Communications Corporation and server implementations from vendors like Microsoft and open-source projects coordinated in communities such as the Apache Software Foundation.

Protocol Details and Syntax

The document specifies header fields, challenge formats, and response formatting that integrate with HTTP status codes standardized in contemporaneous RFCs. Syntax rules reference augmented BNF styles used in IETF documents and align with character encoding concerns addressed by standards bodies like ISO/IEC and the Internet Architecture Board. The Basic scheme encodes user credentials using an octet sequence mechanism similar to encodings described in specifications from IETF registries, while Digest details nonce handling, quality-of-protection directives, and the use of MD5-like digest calculations influenced by algorithm specifications authored by figures associated with RSA Laboratories and cryptographic research groups at institutions such as MIT Lincoln Laboratory. The specification provides examples demonstrating interoperability with servers and clients originating from projects at University of California, Berkeley and industry products from IBM.

Security Considerations and Vulnerabilities

RFC 2617 discusses known security limitations of Basic and Digest authentication in the face of active adversaries and replay attacks studied in academic work at institutions like Carnegie Mellon University and University of Cambridge. The Basic scheme is explicitly weak without transport-layer confidentiality and is often recommended to be combined with secure channels such as those defined by Transport Layer Security standards developed by the IETF and the Internet Engineering Task Force TLS working group. Digest mitigates some threats by avoiding plaintext password transmission, but the RFC acknowledges vulnerabilities related to MD5-style digests pointed out by researchers associated with Bell Labs and cryptanalysis efforts from teams at Ecole Polytechnique and other cryptography research centers. The document's security guidance influenced subsequent security engineering work at organizations including NIST and informed later protocol evolution in standards like those emerging from the IETF Security Area.

Implementations and Interoperability

Implementers across a range of products and projects incorporated the schemes into web servers, browsers, and HTTP libraries. Notable implementations and testbeds came from open-source communities such as the Apache HTTP Server Project and browser vendors including teams at Netscape and Microsoft Internet Explorer. Interoperability tests involved client libraries in programming environments like Python (programming language), Perl, and systems maintained by contributors at GNU Project repositories. The RFC's examples and interoperability notes were used in deployment scenarios at major institutions such as NASA and research networks at CERN, influencing best practices adopted by commercial providers and academic sites.

History and Standardization Context

RFC 2617 was published in June 1999 during a period of active revision of HTTP specifications, following earlier RFCs and contemporary updates culminating in later HTTP/1.1 clarifications. Its authors were participants in IETF working groups engaged with HTTP and web architecture, and its issuance reflects consensus processes common to IETF document progression alongside milestones like the publication of RFCs on HTTP and security. The specification both codified prevailing practice and provided a foundation for subsequent work addressing authentication, contributing to discussions in standards forums and influencing later documents developed by the IETF HTTP Working Group and security-oriented groups within the IETF.

Category:Internet standards