UUID support

CPIX Key Identifier UUID Requirements

Key Identifiers (kid) in CPIX must use valid UUIDs of version 1, 3, 4, or 5 as defined by RFC 4122. This requirement comes from the CPIX standard (DASH-IF Implementation Guidelines), which references the MPEG Common Encryption (CENC) specification for Key ID formatting.

What this means in practice:

Version 1: Time-based UUIDs (includes timestamp and MAC address)
Version 3: Name-based UUIDs using MD5 hashing
Version 4: Randomly generated UUIDs (most common)
Version 5: Name-based UUIDs using SHA-1 hashing (recommended over v3)

All standard UUID generation libraries automatically produce compliant UUIDs. Version 2 is excluded as it's reserved for DCE Security and rarely used in practice.