Solana Fellowship Assignment – Rust HTTP Server

Overview

Build a Rust-based HTTP server exposing Solana-related endpoints. The server provides functionality to generate keypairs, handle SPL tokens, sign/verify messages, and construct valid on-chain instructions.

HTTP-URL

https://your-url

Response Format

All endpoints return JSON responses in the following format:

Success Response (Status 200)

{
  "success": true,
  "data": { /* endpoint-specific result */ }
}

Error Response ( Status: 400)

{
  "success": false,
  "error": "Description of error"
}

Endpoints Specification

1. Generate Keypair

Generate a new Solana keypair.

Endpoint: POST /keypair

Response:

{
  "success": true,
  "data": {
    "pubkey": "base58-encoded-public-key",
    "secret": "base58-encoded-secret-key"
  }
}

2. Create Token

Create a new SPL token initialise mint instruction.

Endpoint: POST /token/create

Request:

{
  "mintAuthority": "base58-encoded-public-key",
  "mint": "base58-encoded-public-key"
  "decimals": 6
}

Response:

{
  "success": true,
  "data": {
    "program_id": "string",
    "accounts": [{
	    pubkey: "pubkey", 
	    is_signer: boolean, 
	    is_writable: boolean
    }...],
    "instruction_data": "base64-encoded-data"
  }
}

3. Mint Token

Create a mint-to instruction for SPL tokens.

Endpoint: POST /token/mint

Request:

{
  "mint": "mint-address",
  "destination": "destination-user-address",
  "authority": "authority-address",
  "amount": 1000000,
}

Response:

{
  "success": true,
  "data": {
    "program_id": "string",
    "accounts": [
      {
        "pubkey": "pubkey",
        "is_signer": false,
        "is_writable": true
      }...,
    ],
    "instruction_data": "base64-encoded-data"
  }
}

4. Sign Message

Sign a message using a private key.

Endpoint: POST /message/sign

Request:

{
  "message": "Hello, Solana!",
  "secret": "base58-encoded-secret-key"
}

Response:

{
  "success": true,
  "data": {
    "signature": "base64-encoded-signature",
    "public_key": "base58-encoded-public-key",
    "message": "Hello, Solana!"
  }
}

Error Response (Missing Fields):

{
  "success": false,
  "error": "Missing required fields"
}

5. Verify Message

Verify a signed message.

Endpoint: POST /message/verify

Request:

{
  "message": "Hello, Solana!",
  "signature": "base64-encoded-signature",
  "pubkey": "base58-encoded-public-key"
}

Response:

{
  "success": true,
  "data": {
    "valid": true,
    "message": "Hello, Solana!",
    "pubkey": "base58-encoded-public-key"
  }
}

6. Send SOL

Create a SOL transfer instruction. Should only process valid inputs, figure out what we mean when we say valid inputs

Endpoint: POST /send/sol

Request:

{
  "from": "sender-address",
  "to": "recipient-address",
  "lamports": 100000,
}

Response:

{
  "success": true,
  "data": {
    "program_id": "respective program id",
    "accounts": [
      "address of first account",
      "address of second account"
    ],
    "instruction_data": "instruction_data"
  }
}

7. Send Token

Create an SPL token transfer instruction.

Endpoint: POST /send/token

Request:

{
  "destination": "destination-user-address",
  "mint": "mint-address",
  "owner": "owner-address",
  "amount": 100000,
}

Response:

{
  "success": true,
  "data": {
    "program_id": "respective program id",
    "accounts": [
	    {
		    pubkey: "pubkey", 
		    isSigner: boolean,
	    }
    ],
    "instruction_data": "instruction_data"
  }
}

Technical Details

Signature Implementation

• Uses Ed25519 for signing/verification
• Base58 encoding for public/private keys
• Base64 encoding for signatures

Error Handling

• Detailed error messages in response
• Proper validation of all input fields
• Consistent error message format

Security Considerations

• No private keys stored on server
• All cryptographic operations use standard libraries
• Input validation for all endpoints
• Proper error handling to avoid information leakage