Overview
ISO 26430-6:2009 specifies the Auditorium Security Message (ASM) protocol for secure, interoperable communication of security-critical information across an intra-theater D‑Cinema (digital cinema) network. Part of the ISO 26430 family, this standard defines a request–response messaging model (RRP) for exchanging commands and responses between a Security Manager and remote Secure Processing Blocks (SPBs). The specification mandates Transport Layer Security (TLS) for authentication and confidentiality and Key-Length-Value (KLV) encoding for message format, enabling consistent link encryption keying and other auditorium-level security operations.
Key Topics and Requirements
- Message security: ASMs are carried over TLS. The standard constrains TLS to ensure interoperability:
- TLS 1.0 protocol
- RSA 2048-bit public keys with exponent 65537
- AES‑128‑CBC symmetric cipher
- SHA‑1 hash algorithm
- CipherSuite TLS_RSA_WITH_AES_128_CBC_SHA
- TLS record size set to 512 bytes and null compression
- Message encoding: KLV encoding per SMPTE 336M using fixed-length pack encoding. The KLV length field uses a 4‑byte long-form BER value.
- Request–Response Pair (RRP) model: Each ASM is a Request from an Initiator followed by a Response from a Responder. Messages include a Request_ID echoed in the response; multi-byte integers are big-endian.
- General command set: Defines general-purpose ASMs (e.g., GetTime, GetEventList, GetEventID, QuerySPB) and a dedicated set for Link Encryption (LE) keying (e.g., LEKeyLoad, LEKeyQuery, LEKeyPurge).
- Batches and data structures: Supports fixed-size batches (xxxBatch) with explicit counts and item lengths for efficient processing in secure silicon.
- Conformance and interoperability: Normative conformance language (shall/should/may) guides implementers; the spec was adopted from SMPTE 430‑6.
Applications and Users
ISO 26430-6 is intended for:
- Cinema system integrators deploying secure intra-theater networks
- Hardware manufacturers of Image Media Blocks (IMBs), Secure Processing Blocks (SPBs), and Link Decryptor Blocks (LDBs)
- Software developers implementing D‑Cinema security managers, key management agents, and network protocol stacks
- Exhibition operators requiring standardized link encryption keying, auditability, and secure content delivery within a multiplex
Practical uses include secure delivery and rotation of link encryption keys, remote querying of SPB status, event synchronization, and audit-ready security event communications across a theater’s internal network.
Related Standards
- ISO 26430 (other parts): Part 1 (Key delivery), Part 2 (Digital certificate), Part 3 (Extra-theater message format), Part 4 (Log record format), Part 5 (Security log event), Part 9 (Key delivery bundle)
- SMPTE 336M (KLV encoding), SMPTE 430‑1/2/5 (D‑Cinema operations), RFC 2246 (TLS 1.0), RFC 3268 (AES in TLS)
Keywords: ISO 26430-6, digital cinema, D-cinema, auditorium security message, ASM, intra-theater communications, TLS, KLV, link encryption, SPB, cinema security standard.
Open preview (PDF)Digital cinema (D-cinema) operations — Part 6: Auditorium security messages for intra-theater communications
