Fix: Private Key Exposure in Web3 Authentication

[grich88]

🔧 Fix Implementation

This PR addresses the critical private key exposure vulnerability identified in issue #345.

Changes Made

• Remove client-side private key access entirely
• Implement secure server-side signing with authentication
• Add secure key management with encryption
• Prevent wallet compromise through XSS attacks
• Add audit logging for all key operations

Security Improvements

1. Eliminates client-side private key exposure
2. Implements server-side signing with proper authentication
3. Uses secure key management with encryption
4. Adds audit logging for all key operations
5. Implements proper error handling

Files Modified

• rontend/src/web3AuthContext.tsx - Remove vulnerable getPrivateKey method
• rontend/src/solanaRPC.ts - Replace with secure wallet connection
• �ackend/api/src/routes/signing.ts - Add server-side signing endpoint
• �ackend/api/src/services/keyManagement.ts - Add secure key management

Code Changes

1. Remove Vulnerable Method

` ypescript
// REMOVE this vulnerable method entirely
// export const getPrivateKey = async (): Promise => {
// return await solanaRPCInstance.getPrivateKey();
// };

// REPLACE with secure server-side signing
export const signTransaction = async (transaction: Transaction): Promise => {
const response = await fetch('/api/sign-transaction', {
method: 'POST',
body: JSON.stringify({ transaction }),
headers: {
'Content-Type': 'application/json',
'Authorization': Bearer
}
});

if (!response.ok) {
throw new Error('Transaction signing failed');
}

return response.json();
};
`

Impact

• Eliminates client-side private key exposure
• Prevents wallet compromise through XSS
• Implements secure server-side signing
• Adds proper authentication and authorization
• Follows security best practices for key management

Researcher: grich88 ([email protected])

Closes #345