CuraChain: Decentralized Medical Crowdfunding Protocol

CuraChain is a blockchain-based medical crowdfunding platform built on the Solana network. It provides a transparent, secure, and efficient way to connect patients requiring medical funding with donors worldwide, ensuring that funds reach verified patients through a robust verification and escrow system.

Core Features

Patient Case Management

Case Submission: Patients can submit medical cases with detailed descriptions, treatment cost estimates, and supporting documentation links
Unique Identifiers: Each case receives a unique ID (e.g., "CASE0001") for easy reference and tracking
Case Lookup: Efficient on-chain mechanism to retrieve case details using unique identifiers

Advanced Verification System

Trusted Verifier Network: Platform administrators maintain a network of authorized medical verifiers
Quorum-based Verification: 70% of verifier votes required for case approval
Time-constrained Verification: Verifiers must complete verification within 10 days
Admin Override: Administrators can approve or reject cases after the 10-day verification window to prevent stalled cases
Rejection Management: Ability to close rejected cases to maintain system cleanliness

Secure Fund Management

Escrow System: All donations are held in secure program-derived address (PDA) escrows
Multi-signature Authorization: Fund release requires multiple authorizations (default: 3 signatures)
Dual-asset Support: Accept both SOL and SPL token donations
Token Vaults: Separate token vaults created for different SPL token donations
Treatment Facility Payments: Direct disbursement to verified treatment facilities

NFT Receipt System

Donation Verification: NFT receipts provide immutable proof of contribution
Metadata-rich Tokens: Includes details about donation amount, recipient case
Collection Hierarchy: Organized in a collection for easy verification and tracking
URI-based Metadata: Supports customizable metadata to enhance donor experience

Event Tracking

On-chain Event Logging: Comprehensive event system for tracking all actions
Transaction Verification: Ability to verify all operations through blockchain explorers
Audit Trail: Complete history of case verification, donations, and fund releases

Technical Architecture

Smart Contract Design

Built using the Anchor framework on Solana with a focus on security, efficiency, and scalability-

Account Structure

Administrator Account: Controls platform operations, verifier management
Verifier Accounts: Authorized entities that validate patient claims
Patient Case Accounts: Stores patient information, funding goals, and verification status
Case Counter & Lookup: Global counter and efficient lookup system for case ID management
Escrow Accounts: Secure holding for donated funds with multisig release
Donor Accounts: Tracks donations and enables NFT receipt issuance
Proposal Accounts: Manages fund release proposals and approvals

Security Design

Program Derived Addresses (PDAs): Used for secure, deterministic account derivation
Bump Seed Management: Properly manages PDA derivation to prevent collision attacks
Authority Checks: Strict checks on account authorities and signers
Time-based Controls: Enforces time windows for operations like verification

Core Features Implementation

Time-based Verification Window:

// Only allow admin override after 10 days from submission
let now = Clock::get()?.unix_timestamp;
require!(
    now >= patient_case.submission_time + ALLOWED_VERIFICATION_TIME as i64, 
    CuraChainError::VerifiersVerificationActive
);

Verifier Quorum System:

// Check if yes votes is 70% of total votes
let approval_threshold_70_scaled = total_votes_u32_scaled
    .checked_mul(70)
    .ok_or(CuraChainError::OverflowError)?
    .checked_div(100)
    .ok_or(CuraChainError::OverflowError)?;

Fund Management:

// Multisig requirement (default: 3 signers)
pub const MULTISIG_THRESHOLD: u8 = 3;

Verification System

CuraChain implements a sophisticated multi-level verification system:

Verifier Network

Verifier Registration: Administrators add trusted medical verifiers to the platform
Global Registry: All authorized verifiers are tracked in a global registry
Verifier Rotation: Administrators can add or remove verifiers as needed

Verification Process

Case Submission: Patient submits case with medical documentation
Verifier Review: Authorized verifiers review the case and vote (yes/no)
Quorum Check: System calculates if 70% of votes are positive
Automated Verification: Case automatically verified when quorum reached
Escrow Creation: Upon verification, system automatically creates donation escrow

Admin Override Functionality

The platform includes a time-sensitive admin override capability:

Time Window: Verifiers have 10 days (864,000 seconds) to vote
Verification Deadlock: If verifiers don't respond within timeframe
Admin Action: Administrator can override and approve/reject case
Escrow Management: If approved, escrow is automatically created

NFT System

CuraChain incorporates an innovative NFT-based donation receipt system:

NFT Collection

Master Collection: Platform maintains a master NFT collection
Collection Verification: All donation NFTs are verified members of the collection
Metadata Structure: Standardized metadata format for all donation receipts

Donor Experience

First Donation: First-time donors to a case receive an NFT receipt
Metadata Storage: NFT includes donation details and case information
URI-based Metadata: Supports rich metadata through customizable URIs
Metadata Updates: For repeat donors, metadata is updated with new donation information

Implementation Details

// Create Metadata Account For First-time Donations
let data_v2 = DataV2 {
    name: format!("Recognition NFT -- {}", case_id),
    symbol: "CURA".to_string(),
    uri: nft_uri,
    seller_fee_basis_points: 0,
    creators: None,
    collection: Some(Collection {
        verified: false,
        key: ctx.accounts.parent_recognition_collection_nft.key(),
    }),
    uses: None
};

Fund Management

Donation Process

Verified Cases Only: System only allows donations to verified cases
Multiple Asset Types: Support for both SOL and SPL token donations
Token Vaults: Creation of specific vaults for each token type
Donation Tracking: All donations tracked on-chain with donor information
Donation Limits: Prevents over-funding of cases with configurable buffer

Fund Release

Proposal Creation: Any multisig member can propose fund release
Approval Process: Requires approval from minimum threshold of members (default: 3)
Execution: Transfers funds directly to specified treatment facility
SPL Handling: Creates associated token accounts for treatment facility if needed
Tracking: All transfers are tracked with on-chain events

Multisig Implementation

// AUTHORIZED MULTISIG TRANSFERS ACCUMULATED FUNDS TO TREATMENT WALLET 
pub fn release_funds<'info>(ctx: Context<'_, '_, '_, 'info, ReleaseFunds<'info>>, 
    case_id: String, proposal_index: u64) -> Result<()> {
    instructions::release_funds(ctx, case_id, proposal_index)?;
    Ok(())
}

Use Cases

For Patients

Global Reach: Access donors worldwide without geographic limitations
Transparent Process: Clear verification system builds donor trust
Reduced Fraud Risk: Verified medical cases prevent fraudulent fund collection
Direct Payment: Funds transferred directly to treatment facilities

For Donors

Verified Recipients: Confidence that donations reach legitimate patients
Donation Proof: NFT receipts provide verifiable donation records
Multiple Assets: Flexibility to donate SOL or SPL tokens
Transparent Tracking: Full visibility into fund collection and disbursement

For Healthcare Providers

Reliable Funding: Direct access to verified funds for patient treatment
Administrative Efficiency: Reduced paperwork through blockchain automation
Global Patient Pool: Connect with patients seeking funding from anywhere
Automated Disbursement: Streamlined payment process with multisig security

Project Flow

Below are comprehensive Mermaid diagrams explaining the CuraChain protocol operations in detail:

1. Platform Initialization Flow

flowchart TD
    A[System Deployment] --> B[Initialize Administrator]
    B --> C[Setup Multisig Authority]
    C --> D[Initialize Global Verifiers Registry]
    C --> E[Initialize Case Counter]
    
    D --> F[Add Trusted Verifiers]
    F --> G[Update Verifiers Registry]
    
    E --> H[Case ID System Ready]
    G --> I[Platform Ready for Operations]
    H --> I

2. Patient Case Submission and Verification Flow

flowchart TD
    A[Patient Submits Case] --> B[Generate Unique Case ID]
    B --> C[Create Patient Case PDA]
    C --> D[Store Medical Records & Funding Amount]
    D --> E[Record Case Submission Time]
    E --> F[Enter Verification Queue]
    
    F --> G{Verifiers Review Case}
    G -->|Yes Vote| H[Increment Yes Counter]
    G -->|No Vote| I[Increment No Counter]
    
    H --> J{70% Yes Threshold Met?}
    I --> J
    
    J -->|Yes| K[Mark Case as Verified]
    J -->|No| L{All Verifiers Voted?}
    
    K --> M[Create Escrow Account]
    M --> N[Case Ready for Donations]
    
    L -->|Yes| O[Case Not Verified]
    L -->|No| P[Wait for More Votes]
    
    P --> Q{10 Days Passed?}
    Q -->|Yes| R[Admin Override Option]
    Q -->|No| G
    
    R -->|Approve| K
    R -->|Reject| O
    
    O --> S[Case Can Be Closed]

3. Donation Process and NFT Receipt System Flow

flowchart TD
    A[Donor Views Verified Cases] --> B{Select Case and Asset Type}
    B -->|SOL| C[SOL Donation Transaction]
    B -->|SPL Token| D[SPL Token Donation Transaction]
    
    C --> E[Verify Case Status]
    D --> E
    
    E -->|Not Verified| F[Reject Donation]
    E -->|Verified| G[Accept Donation]
    
    G -->|First Donation to Case| H[Create Donor Account PDA]
    G -->|Repeat Donation| I[Update Donor Account]
    
    H --> J[Transfer Funds to Escrow]
    I --> J
    
    J -->|SOL| K[Update SOL Balance in Case]
    J -->|SPL Token| L[Create/Update Token Vault]
    
    K --> M[Check for First-time Donation]
    L --> M
    
    M -->|First Time| N[Mint NFT Receipt]
    M -->|Repeat| O[Update NFT Metadata]
    
    N --> P[Create Metadata with Case Details]
    N --> Q[Add to CuraChain Collection]
    
    O --> R[Update Metadata URI]
    
    P --> S[Emit Donation Event]
    Q --> S
    R --> S
    
    S --> T[Donation Complete]

4. Fund Release and Multisig Approval Flow

flowchart TD
    A[Treatment Facility Identified] --> B[Multisig Member Proposes Transfer]
    B --> C[Create Proposal PDA]
    C --> D[Record Proposal Details]
    D --> E[Automatic First Approval from Proposer]
    
    E --> F[Other Multisig Members Review]
    F -->|Approve| G[Increment Approval Counter]
    F -->|Reject| H[Increment Rejection Counter]
    
    G --> I{Threshold Reached?}
    H --> J{Majority Rejected?}
    
    I -->|Yes - ≥3 Approvals| K[Mark Proposal as Approved]
    I -->|No| F
    
    J -->|Yes| L[Mark Proposal as Rejected]
    J -->|No| F
    
    K --> M[Execute Fund Transfer]
    
    M -->|SOL Transfer| N[Transfer SOL to Treatment Facility]
    M -->|SPL Transfer| O[Transfer Tokens to Facility ATAs]
    
    N --> P[Update Case Funding Status]
    O --> P
    
    P --> Q[Emit Fund Release Event]
    Q --> R[Mark Proposal as Executed]

5. Admin Override Process After 10-Day Period

flowchart TD
    A[Case in Verification for 10+ Days] --> B[Admin Reviews Case]
    B --> C{Verification Decision}
    
    C -->|Approve| D[Admin Signs Override Transaction]
    C -->|Reject| E[Admin Signs Rejection Transaction]
    
    D --> F[Check Time Requirements]
    E --> F
    
    F -->|<10 Days Passed| G[Reject: Verifiers Still Active]
    F -->|≥10 Days Passed| H[Allow Override]
    
    H -->|Approve Case| I[Set Case Verification to True]
    H -->|Reject Case| J[Leave Case Unverified]
    
    I --> K[Create Escrow Account]
    I --> L[Emit Verification Event]
    J --> M[Case Can Be Closed]
    
    K --> N[Case Ready for Donations]
    L --> N

6. Complete System Interaction Flow

flowchart TD
    subgraph Initialization
    A[Admin Setup] --> B[Verifier Network]
    end
    
    subgraph Case_Submission
    C[Patient Submits Case] --> D[Generate Case ID]
    D --> E[Enter Verification]
    end
    
    subgraph Verification_Process
    E --> F{Verifier Voting}
    F -->|70% Yes| G[Case Verified]
    F -->|<70% Yes| H{10 Days Passed?}
    H -->|Yes| I[Admin Override]
    H -->|No| F
    I -->|Approve| G
    I -->|Reject| J[Not Verified]
    end
    
    subgraph Funding_Phase
    G --> K[Escrow Created]
    K --> L[Accept Donations]
    L --> M[Generate NFT Receipts]
    L --> N[Track Funding Progress]
    end
    
    subgraph Fund_Release
    N --> O[Multisig Proposal]
    O --> P{Threshold Approvals?}
    P -->|Yes| Q[Transfer to Facility]
    P -->|No| O
    end
    
    J --> R[Case Closed]
    Q --> S[Case Completed]
    
    B --> C

Detailed Process Flow Description:

Platform Initialization:
- Administrator account is created with required permissions
- Multisig authority established with configurable threshold (default: 3)
- Global verifiers registry initialized to track authorized medical validators
- Case counter PDA setup to generate sequential case IDs
Patient Submission Flow:
- Patient submits medical case with documentation and funding goal
- System assigns unique identifier (e.g., "CASE0001") through case counter
- Patient case PDA created and linked to submitter's wallet
- Submission timestamp recorded for verification deadline tracking
Verification Process:
- Authorized verifiers review case documentation
- Each verifier casts a single vote (yes/no) with duplicate prevention
- System tracks verification statistics in patient case account
- If 70% of verifiers approve, case is automatically verified
- If insufficient votes after 10 days (864,000 seconds), admin can override
- Admin override creates escrow if approved, or leaves case unverified if rejected
Donation System:
- Donors can only contribute to verified cases
- Support for both SOL and SPL token donations
- First-time donors receive NFT receipts with case metadata
- Repeat donors get updated NFT metadata reflecting total contributions
- All NFTs are verified members of the CuraChain collection
- Donation limits prevent over-funding with configurable buffer
Fund Release Mechanism:
- Any multisig member can propose fund transfer to treatment facility
- Required number of approvals (default: 3) must be reached
- Proposal tracking ensures each member can only vote once
- Fund transfer executes automatically when threshold reached
- System handles both SOL and SPL token transfers to facility
- Creates associated token accounts for facility as needed

This comprehensive flow ensures secure, transparent fund management with appropriate checks and balances throughout the medical crowdfunding process.

Getting Started

Prerequisites

Solana CLI tools (v2.1.0+)
Anchor framework (v0.31.1+)
Node.js (v16+) and yarn/npm
Solana wallet

Installation

# Clone the repository
git clone https://github.com/yourusername/curachain.git
cd curachain

# Install dependencies
yarn install

# Build the program
anchor build

# Run tests
anchor test

Key Setup Commands

# Initialize administrator (first-time setup)
anchor run initialize-admin

# Add verifiers
anchor run add-verifier -- --keypair <VERIFIER_KEYPAIR_PATH>

# Deploy to devnet
anchor deploy --provider.cluster devnet

# Program ID on Devnet:
   Program Id: C6MLrHQCiBiTUXHgG5S1MJjz32mBpapSjoWHRG62sCVK
   Link: [Curachain Program on Solana Explorer](https://explorer.solana.com/address/C6MLrHQCiBiTUXHgG5S1MJjz32mBpapSjoWHRG62sCVK?cluster=devnet)

License

This project is licensed under the MIT License - see the LICENSE file for details.

MIT License

Copyright (c) 2025 CuraChain

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Name		Name	Last commit message	Last commit date
migrations		migrations
programs/curachain		programs/curachain
target		target
tests		tests
.gitignore		.gitignore
.prettierignore		.prettierignore
Anchor.toml		Anchor.toml
Cargo.lock		Cargo.lock
Cargo.toml		Cargo.toml
LICENSE		LICENSE
README.md		README.md
package.json		package.json
tsconfig.json		tsconfig.json
yarn.lock		yarn.lock

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