Preventing Signature Replay on Solana with Ed25519 Native Programs

When using the Native Ed25519 Program on Solana to verify a message signature, it’s essential to implement measures to prevent replay attacks. One common technique is to add a pre-instruction that contains the signature, message, and public key of the sender. In this article, we’ll explore how to achieve this security feature in your custom program.

Why Prevent Signature Replay?

Signature replay attacks occur when an attacker intercepts and reuses a previously verified signature. This can be devastating for Solana-based systems, as it allows attackers to impersonate legitimate users and execute malicious transactions without consequence.

Implementing Ed25519 Native Programs on Solana

To prevent signature replay, we’ll use the Solana-program library, which provides an implementation of native programs on the Solana blockchain. We’ll focus on creating a pre-instruction that contains the signature, message, and public key of the sender.

Here’s an example of how to create a pre-instruction using TypeScript:

import { Program } from '@solana-program/spl-program';

import { solanaProgram } from '../src';


const programId = 'your_program_id'; // Replace with your program ID


class SignatureReplayPreInstruction extends Program {

  async getProgramData(programId: string): Promise {

    const signature = 'your_signature_here'; // Replace with the actual signature

    const message = 'your_message_here'; // Replace with the actual message

    const publicKey = 'your_public_key_here'; // Replace with the actual public key


    return JSON.stringify({

      signature,

      message,

      publicKey,

    });

  }


  async execute(programId: string, data: string): Promise {

    if (data.startsWith('pre_instruction')) {

      const preInstruction = JSON.parse(data.substring(9));

      console.log(Received pre-instruction with signature ${preInstruction.signature}, message ${preInstruction.message}, and public key ${preInstruction.publicKey});

    }

  }

}


// Initialize the program

const program = new solanaProgram(programId, SignatureReplayPreInstruction);

In this example, we define a SignatureReplayPreInstruction class that extends the Program class. The getProgramData method returns a string containing the signature, message, and public key of the sender.

The execute method checks if the received data starts with ‘pre_instruction’. If it does, it parses the data as JSON and logs the contents to the console.

Using the Pre-Instruction in Ed25519 Native Programs

To use the pre-instruction in an Ed25519 native program, you’ll need to modify the nativeScript function to extract the signature, message, and public key from the received data. Here’s an example of how to do this:

“`typescript

import { Program } from ‘@solana-program/spl-program’;

import { ed25519NativeScript } from ‘../src’;

const programId = ‘your_program_id’; // Replace with your program ID

class SignatureReplayPreInstruction extends Program {

async getProgramData(programId: string): Promise {

const signature = ‘your_signature_here’; // Replace with the actual signature

const message = ‘your_message_here’; // Replace with the actual message

const publicKey = ‘your_public_key_here’; // Replace with the actual public key

return JSON.stringify({

signature,

message,

publicKey,

});

}

async execute(programId: string, data: string): Promise {

if (data.startsWith(‘pre_instruction’)) {

const preInstructionData = data.substring(9);

const [signature, message, publicKey] = preInstructionData.split(‘,’);

console.