image-verification

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name: image-verification description: Validates image file signatures using Magic Bytes and calculates SHA-256 cryptographic hash license: MIT compatibility: opencode metadata: audience: developers workflow: clinical-pipeline

What I do

I verify image authenticity before processing. I check file signatures (Magic Bytes) to confirm the file is a valid image type and calculate a SHA-256 hash for audit trails and duplicate detection.

When to use me

Use this when:

• An image is uploaded and needs validation
• You need to ensure the file is actually an image (not malicious content)
• You need a cryptographic hash for the image (audit/duplicate check)

Key Concepts

• Magic Bytes: File signature bytes that identify the format (e.g., FF D8 FF for JPEG)
• SHA-256 Hash: 256-bit cryptographic hash for integrity and identification
• Crypto Subtle: Browser Web Crypto API for cryptographic operations

Source Files

• services/crypto.ts: Cryptographic operations
• services/vision.ts: Image validation helpers

Code Patterns

• Use crypto.subtle.digest('SHA-256', ...) for hashing
• Check first bytes of ArrayBuffer for magic bytes
• Reject invalid files immediately with clear error messages

Operational Constraints

• Must reject non-image files before any processing
• Hash is used for deduplication and audit trail
• Always log verification results for traceability