Doc. A/96 3 February 2004 ATSC Standard: ATSC Interaction Channel Protocols Advanced Television Systems Committee 1750 K Street, N.W. Suite 1200 Washington, D.C. 20006 www.atsc.org ATSC ATSC Interaction Channel Protocols 3 February 2004 The Advanced Television Systems Committee, Inc., is an international, non-profit organization developing voluntary standards for digital television. The ATSC member organizations represent the broadcast, broadcast equipment, motion picture, consumer electronics, computer, cable, satellite, and semiconductor industries. Specifically, ATSC is working to coordinate television standards among different communications media focusing on digital television, interactive systems, and broadband multimedia communications. ATSC is also developing digital television implementation strategies and presenting educational seminars on the ATSC standards. ATSC was formed in 1982 by the member organizations of the Joint Committee on InterSociety Coordination (JCIC): the Electronic Industries Association (EIA), the Institute of Electrical and Electronic Engineers (IEEE), the National Association of Broadcasters (NAB), the National Cable Television Association (NCTA), and the Society of Motion Picture and Television Engineers (SMPTE). Currently, there are approximately 140 members representing the broadcast, broadcast equipment, motion picture, consumer electronics, computer, cable, satellite, and semiconductor industries. ATSC Digital TV Standards include digital high definition television (HDTV), standard definition television (SDTV), data broadcasting, multichannel surround-sound audio, and satellite direct-to-home broadcasting. 2 ATSC ATSC Interaction Channel Protocols 3 February 2004 Table of Contents 1. SCOPE........................................................................................................................................................7 1.1 Purpose 7 1.2 Organization 7 2. REFERENCES............................................................................................................................................7 2.1 Normative References 7 2.2 Informative References 8 2.3 Reference Acquisition 8 2.3.1 ATSC Standards 8 2.3.2 IETF Standards 8 2.3.3 ISO Standards 9 2.3.4 ITU Standards 9 2.3.5 SMPTE Standards 9 2.3.6 W3C Standards 9 3. DEFINITIONS AND STRUCTURE..............................................................................................................9 3.1 Compliance Notation 9 3.2 Acronyms and Abbreviations 9 3.3 Global Terms 11 4. SYSTEM OVERVIEW AND INTRODUCTION ..........................................................................................11 4.1 Architecture 11 4.2 Remote Interactivity 13 4.3 Service and Channel Providers 13 4.4 ITV Clients 13 4.5 Protocol Layered Architecture 14 4.6 Relation with other ATSC Standards 14 5. PHYSICAL AND DATA-LINK LAYER PROTOCOLS ..............................................................................15 6. NETWORK AND TRANSPORT-LAYER PROTOCOLS...........................................................................15 6.1 Network-Layer Support 15 6.1.1 IP 16 6.1.2 ICMP 16 6.2 Transport-Layer Support 16 6.2.1 UDP 16 6.2.2 TCP 16 7. APPLICATION LAYER PROTOCOLS .....................................................................................................16 7.1 HTTP 16 7.1.1 Role definitions 16 3 ATSC ATSC Interaction Channel Protocols 3 February 2004 7.1.1.1 Client 17 7.1.1.2 Server 17 7.1.1.3 Proxy Server 17 7.1.2 HTTP Profiles 17 7.1.2.1 Client Profile 17 7.1.2.1.1 Mandatory features 17 7.1.2.1.1.1 Closing Connections 17 7.1.2.1.1.2 User Agent identification 17 7.1.2.1.2 Recommendations 17 7.1.2.1.2.1 Cache control and time source 17 7.1.2.1.2.2 Support for HTTP/1.0 responses 18 7.1.2.1.2.3 Use of Referrer request header 18 7.1.2.1.2.4 From request header 18 7.1.2.1.2.5 GET and POST usage in form submissions 18 7.1.2.1.2.6 HTTP Basic Authentication use 18 7.1.2.1.2.7 Use of Accept Request headers 18 7.1.2.2 Server Profile 18 7.1.2.2.1 HTTP version requirement 18 7.1.2.2.2 Mandatory features 18 7.1.2.2.2.1 Entity Body and Content-Type 18 7.1.2.2.3 Recommendations 19 7.1.2.2.3.1 Range Requests 19 7.1.2.3 Proxy Server Profile 19 7.1.2.3.1 HTTP version requirement 19 7.1.3 HTTP State Management 19 7.1.3.1 Sending Cookies 19 7.1.3.2 Receiving Cookies 19 7.2 DNS 19 7.3 Configuration Services 19 8. CERTIFICATES AND CERTIFICATE REVOCATION LISTS...................................................................20 8.1 Generalities 20 8.2 Minimal Implementation Profile for Certificates 20 8.2.1 Constraints on Certificate Fields 21 8.2.1.1 Constraints on Version 22 8.2.1.2 Constraints on Issuer and Subject 22 8.2.1.3 Supported Cryptographic Algorithms for Signature and Subject Public Key Info 22 8.2.2 Constraints on Extension Fields 23 8.2.2.1 Constraints on the Subject Alternative Name 23 8.2.2.2 Constraints on the Issuer Alternative Name 23 8.2.2.3 Constraints on CRL Distribution Points 23 8.2.2.4 Constraints on the Authority Information Access 23 8.3 Minimal Implementation Profile for CRLs 23 8.3.1 Constraints on CRL fields 24 8.3.1.1 Constraints on Version 24 4 ATSC ATSC Interaction Channel Protocols 3 February 2004 8.3.1.2 Constraints on Signature and Signature Algorithm 24 8.3.1.3 Constraints on Issuer 24 8.3.2 Constraints on CRL Entry Extension Fields 24 8.3.3 Constraints on CRL Extension Fields 25 8.3.3.1 Constraints on Issuer Alternative Name 25 8.4 Certificate Processing and Operations 25 8.4.1 Certificate Status Validation 25 8.4.2 Certificate Path Build-Up and Validation 25 8.4.2.1 Trust Association 25 8.4.2.2 Path Validation 25 8.4.2.3 Name Matching 25 9. SECURE CHANNEL PROTOCOLS .........................................................................................................26 9.1 TLS 26 9.1.1 Protocol Version Support 26 9.1.2 TLS Cipher Suites 26 9.1.3 Other Cipher Suites 27 9.2 HTTPS 27 9.2.1 Protocol Identifier 27 9.2.2 Port Number 27 Annex A: Informative Notes on Access Technologies for Physical and Data-Link Layer Protocols 28 5 ATSC ATSC Interaction Channel Protocols 3 February 2004 Listing of Figures and Tables Figure 4.1 Architecture to provide ITV services over the interactive channel. 12 Figure 4.2 Architecture where the ITV client constitutes an element of a home LAN. 12 Figure 4.3 Local interactivity (a) compared to remote interactivity (b). 13 Figure 4.4 The five-layer model for client/server communication protocols. 14 Figure 4.5 Relation of Interaction Channel Protocols and other ATSC standards. 15 Table 8.1 MIP Support of PKIX Certificate Fields and Extensions 21 Table 8.2 Algorithms for Digital Signatures 22 Table 8.3 Algorithms for Key Agreement 22 Table 8.4 MIP support of PKIX CRL Fields and Extensions 24 Table 9.1 TLS Cipher Suites 26 6 ATSC ATSC Interaction Channel Protocols 3 February 2004 ATSC Standard: ATSC Interaction Channel Protocols 1. SCOPE 1.1 Purpose This standard defines a core suite of protocols to enable remote interactivity in television environments. Remote interactivity requires the use of a two-way interaction channel that enables communications between the client device and remote servers. Examples of remote interactivity include E-commerce transactions during commercials, electronic banking, polling, email services, or other services yet to be defined. 1.2 Organization The document is organized as follows: Section 1: Describes the purpose and the organization of the document. Section 2: Lists references and applicable documents. Section 3: Provides definitions of terms, acronyms, abbreviations, syntax format, and code points. Section 4: Provides an architectural overview and an introduction to the Interaction Channel Protocols. Section 5: Describes the physical and data-link layer of the Interaction Channel Protocols. Section 6: Specifies the network and transport layers of the Interaction Channel Protocols. Section 7: Specifies the application layer of the Interaction Channel Protocols. Section 8: Specifies a profile for certificates and certificate revocation lists. Section 9: Specifies a protocol suite for establishing secure channels. Annex A: Provides additional information on access technologies. 2. REFERENCES 2.1 Normative References [RFC 791] Internet Protocol , RFC 791, IETF [RFC 768] User Datagram Protocol, RFC 768, IETF [RFC 793] Transmission Control Protocol, RFC 793, IETF [RFC 2246] The TLS Protocol Version 1.0, RFC 2246, IETF [HTTP1.1] Hypertext Transfer Protocol – HTTP/1.1, RFC 2616, IETF [HTTP-AUTH] HTTP Authentication: Basic and Digest Access Authentication, RFC 2617, IETF [HTTP-STATE] HTTP State Management Mechanism, RFC 2965, IETF [RFC 2818] HTTP over TLS, RFC 2818, IETF [RFC 1034] Domain Names – Concepts and Facilities, RFC 1034, IETF 7 ATSC ATSC Interaction Channel Protocols 3 February 2004 [RFC 1035] Domain Names – Implementation and Specifications, RFC 1035, IETF [RFC 2535] Domain Name System Security Extensions, RFC 2535, IETF [RFC 2560] X.509 Internet Public Key Infrastructure Online Certificate Status Protocol, RFC 2560, IETF. [RFC 2929] Domain Name System (DNS) IANA Considerations, RFC 2929, IETF [PKIX] Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile, RFC 3280, IETF [PKIXALGS] Algorithms and Identifiers for the Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile, RFC 3279, IETF [URI] IETF RFC 2396, Uniform Resource Identifiers (URI). Generic Syntax. 1998. [URI-LID] Declarative Data Essence - The Local Identifier (lid:) URI Scheme, SMPTE 343M, SMPTE [UTF-8] UTF-8, A Transformation Format of ISO 10646, RFC 2279, IETF. 2.2 Informative References [DBCAST] ATSC Standard A/90 (2000), Data Broadcast Standard. [PSIP] ATSC Standard A/65 (1997), Program and System Information Protocol for Terrestrial Broadcast and Cable. [FIPS 180-1] FIPS PUB 180-1, Secure Hash Standard, Federal Information Processing Standards [PKCS#1] PKCS #1: RSA Encryption Version 1.5, RFC 2313, IETF. [TRANSP] ATSC Standard A/53 (1995), ATSC Digital Television Standard. [PPP] RFC 1662 “PPP in HDLC-like Framing”, W. Simpson, 21.07.1994. [NTP] Network Time Protocol (Version 3) Specification, RFC 1305, IETF.