# PR: Audit and Document Off-Chain Data in Soroban Contracts

[gelluisaac]

Summary

This PR adds comprehensive documentation identifying all on-chain data structures and fields in the SkillCert Soroban smart contracts that are candidates for migration to off-chain storage.

Type of Change

• Documentation
• Bug fix
• New feature
• Breaking change
• Refactoring

Description

Currently, the Soroban smart contracts store extensive application data (user profiles, course metadata, etc.) directly on-chain, which is not optimal for blockchain technology due to high storage costs and gas inefficiency.

This audit formally documents:

• All data structures storing non-essential string data
• A field-by-field analysis with on-chain necessity assessment
• Complete off-chain database schema mapping
• Recommended minimal on-chain struct definitions

Changes

• Added docs/OFF_CHAIN_DATA_AUDIT.md containing the full audit report

Key Findings

Metric	Count
Structs with off-chain candidates	16
Total string fields to move off-chain	47
Database tables required	6

Structs Analyzed

Contract	Struct	Off-Chain Fields
user_profile	UserProfile	name, email, country, profession, goals
course_access	UserProfile	name, email, profession, goals, country
user_management	UserProfile	full_name, contact_email, profession, country, purpose, profile_picture_url
user_management	LightProfile	full_name, profession, country
course_registry	Course	title, description, category, language, thumbnail_url, level, duration_hours
course_registry	CourseModule	title, position
course_registry	CourseGoal	content
course_registry	CourseCategory	name, description

Off-Chain Database Tables Proposed

1. users — User profile information
2. courses — Course metadata
3. course_modules — Module titles and positions
4. course_goals — Goal content
5. course_categories — Category names and descriptions
6. contract_metadata — Contract schema export data

Files Analyzed

• contracts/user_profile/src/schema.rs
• contracts/course/course_access/src/schema.rs
• contracts/course/course_registry/src/schema.rs
• contracts/user_management/src/schema.rs
• contracts/user_management/src/models/user.rs
• contracts/schema_export/src/lib.rs

Testing

• No code changes — documentation only
• All existing tests pass (no modifications to Rust files)

Checklist

• Documentation follows project standards
• All fields documented verbatim (no assumptions about database size)
• No changes made to Rust source files
• Mapping document provides clear schema for off-chain database

Related Issues

Closes #235 Audit and Identify Off-Chain Data in Contracts

Next Steps

This audit serves as the foundation for:

1. Implementing the off-chain database schema
2. Refactoring on-chain structs to minimal versions
3. Building synchronization mechanisms between on-chain and off-chain data