RFC 6101

RFC 6101
Title	RFC 6101
Type	Request for Comments
Number	6101
Author	The IETF TLS Working Group
Published	February 2011
Status	Historic
Pages	101

RFC 6101

RFC 6101 is a standards-track document from the Internet Engineering Task Force that specifies version 1.0 of the Transport Layer Security protocol. It defines protocol elements, record formats, and negotiated cryptographic algorithms used to provide privacy and data integrity between communicating applications. The document served as a snapshot of the TLS 1.0 specification and was later obsoleted by subsequent standards.

Introduction

RFC 6101 codifies the TLS 1.0 protocol originally derived from the Secure Sockets Layer work at Netscape Communications Corporation, with contributions by engineers participating in Internet Engineering Task Force, IETF TLS Working Group, University of California, Berkeley, MIT, and vendors such as Microsoft, IBM, and Cisco Systems. It describes handshake procedures, cipher suite negotiation, and record layer encapsulation that underpinned secure sessions for HTTP, SMTP, IMAP, and POP3 deployments. The specification captures interoperability agreements used by implementations from organizations like Mozilla Foundation, Apple Inc., and Oracle Corporation.

Background and Purpose

The background to RFC 6101 includes lineage from early protocol work at Netscape Communications Corporation that produced SSL 2.0 and SSL 3.0, with standards maturation occurring via the Internet Engineering Task Force where the IETF TLS Working Group formalized the protocol to support wide interoperability across vendors including Sun Microsystems and Juniper Networks. The purpose of RFC 6101 was to provide a definitive text for TLS 1.0 so implementers at institutions such as National Institute of Standards and Technology, European Organization for Nuclear Research, and commercial entities like Intel Corporation could build interoperable stacks. It also aimed to clarify ambiguities from earlier drafts produced by contributors affiliated with RSA Security, Ericsson, Siemens, and academic groups at Stanford University and Carnegie Mellon University.

Key Specifications and Changes

RFC 6101 specifies the TLS record protocol, handshake protocol, and change cipher spec messages, building on mechanisms first implemented by Netscape Communications Corporation and analyzed in work at MIT Laboratory for Computer Science. The key elements include cipher suite identifiers, PRF construction combining MD5 and SHA-1 as specified by contributors from RSA Security and algorithm choices influenced by standards bodies such as ISO and IETF. The document also codified negotiation behavior used by server and client implementations from vendors like Microsoft, Mozilla Foundation, and Apple Inc., addressing interoperability with stacks developed at University of California, Berkeley and University of Cambridge. RFC 6101 documented record layer fragmentation, MAC computation, and padding rules, reflecting cryptographic practices studied by researchers at Bell Labs and AT&T Labs Research. Changes compared to earlier drafts clarified version negotiation and downgrade signaling that implementers in companies such as Cisco Systems and Juniper Networks had found necessary for multi-vendor environments.

Security Considerations

Security considerations in RFC 6101 address threats recognized by researchers at Carnegie Mellon University, Stanford University, and security firms including Symantec Corporation and Checkpoint Software Technologies. The specification discusses protection against eavesdropping and tampering, relying on cipher suites from RSA Security patents-era algorithms and hashes studied at MIT and NIST. It acknowledges limitations of the MD5 and SHA-1 hash functions, critiques raised in cryptanalysis by teams at Ecole Normale Supérieure and Shandong University, and operational concerns highlighted by practitioners at Google and Facebook. The document also touches on key management interactions with certificate infrastructures operated by vendors like DigiCert, Entrust, and research on protocol downgrade attacks published by groups from University of California, Berkeley and ETH Zurich.

Implementation and Deployment

Implementations of the protocol described in RFC 6101 were produced by major software vendors and open-source projects including Mozilla Foundation (via NSS), OpenSSL Project contributors, Microsoft in its operating systems and servers, and Apple Inc. in platform libraries. Deployments occurred across services such as Apache HTTP Server, nginx, Microsoft Exchange Server, and mail servers at institutions like CERN and NASA. Interoperability testing involved testbeds maintained by IETF task forces and vendor labs at IBM and Intel Corporation. Real-world deployment experiences influenced guidance from NIST and large platform operators such as Google and Amazon.com regarding configuration, cipher selection, and migration strategies.

Reception and Updates

RFC 6101 was received as a consolidation of TLS 1.0 text useful for implementers across academia and industry, with discussion in forums hosted by IETF and analysis by researchers at CMU and Stanford University. Subsequent cryptographic advances and discovered vulnerabilities prompted newer specifications produced by the IETF TLS Working Group—notably TLS 1.1, TLS 1.2, and TLS 1.3—with contributions from organizations including Google, Mozilla Foundation, Microsoft, and Cloudflare. Standards bodies such as IETF and ISO and national agencies like NIST recommended migration away from older constructions codified in RFC 6101 toward designs addressing issues identified by researchers at ETH Zurich and Ecole Polytechnique Fédérale de Lausanne.

Category:Internet standards