Appendix: Feed Identity vs Content Integrity

This appendix complements my article on Podcast Security.

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Podcast security can be thought of in two complementary layers:

1. Content Integrity

• Guarantees that the audio file delivered to a listener is exactly the same as the one published.
• Traditionally involves cryptographic hashes, signatures, and immutability.
• Challenges in podcasting:
• Dynamic ad insertion (different regions get different audio)
• CDN variations and caching
• Personalized content or regional versions
• Result: A canonical audio artifact often does not exist, making episode-level integrity hard to enforce.

2. Feed Identity / Provenance

• Ensures that a listener or app discovers the authoritative feed for a given show.
• Focuses on trusting the source, rather than each audio file:
• Prevents copied or fake feeds from masquerading as the original show
• Reduces the risk of monetization or ad tampering on duplicate feeds
• Feeds act as the primary security anchor, while content may vary dynamically.
• Key insight: In today’s ecosystem, establishing feed identity may provide more practical security guarantees than attempting per-episode integrity. Feed-level trust enables listeners and apps to rely on the original publisher, even when audio content is personalized or region-specific.
• Platform-agnostic: This concept applies regardless of hosting or playback platform.

Visual Diagram

                 +--------------------------+           +--------------------------+
                 |      Podcast Feed        |           |      Podcast Feed        |
                 |      (Original)          |           |      (Original)          |
                 +-----------+--------------+           +-----------+--------------+
                             |                                      |
                -------------------------------          ------------------------------
                |  Listener / App receives    |          | Listener / App receives    |
                |  audio with integrity?      |          | audio may vary per region, |
                |  (same file for everyone)   |          | dynamic ads, CDN, etc.     |
                -------------------------------          ------------------------------
                    Content Integrity                          Feed Identity

Takeaway:

• Content Integrity: Audio may differ per listener due to ads, CDN, region, or personalization.
• Feed Identity: Ensures the listener reaches the correct authoritative feed, even if the audio varies dynamically.