Threat Modeling for Ephemeral Sharing: Understanding Capabilities and Limitations
A pragmatic threat model for ephemeral media sharing: identifying adversary capabilities, trust assumptions, encryption boundaries, and what ephemerality can and cannot prevent.
Why Honest Threat Modeling Matters
In security software, claiming '100% unbreakable privacy' is a sign of snake oil. Rigorous engineering requires defining an explicit threat model: who is the adversary, what are their capabilities, and what guarantees does the system provide?
Ephemeral file sharing provides powerful protections against specific attack vectors, while acknowledging inherent limitations.
Key Architectural Takeaways
- Protects against: accidental link leakage, search engine indexing, long-term cloud compromise.
- Does not protect against: malicious recipients who take screenshots with external cameras.
- Zero-knowledge architecture shields content from server operators and ISP surveillance.
Adversaries We Defend Against
1. Casual snoops: Individuals who find old chat links months later cannot access expired content.
2. Automated crawlers: Search engine bots and scrapers are barred via robots.txt and PIN authentication.
3. Server-side breaches: Because Locky uses a zero-database architecture with salted scrypt derivation, compromised servers hold no plaintext passwords or master file directories.
Adversaries Outside the Scope
If an adversary compromises the recipient's physical device while they are viewing the photo, or if the recipient uses screen recording software, ephemerality cannot prevent local capture. Ephemeral sharing safeguards transmission and retention, not untrusted human recipients.
Try Zero-Knowledge Ephemeral Sharing
Need to share a photo or video privately without permanent digital footprint? Locky strips location metadata client-side in your browser, locks media behind a 4-digit numeric PIN, and guarantees automatic self-destruction in 24 hours.
Related Knowledge Base Guides
EXIF Metadata & Geotags: What Photos Reveal About Your Location
A deep dive into Exchangeable Image File Format (EXIF) data, GPS latitude and longitude tracking, and why client-side metadata sanitization is critical before sharing photos online.
Ephemeral StorageThe Dangers of Permanent Cloud Links: Why 24-Hour Self-Destruct Protects You
Why traditional cloud drives like Google Drive and Dropbox create persistent security vulnerabilities, and how automated ephemeral lifecycles eliminate link-rot and data leaks.