digital_sig.rs

digital_sig.rs

/*
[dependencies]
k256 = "0.13.2"
rand = "0.8.5"
*/

#![allow(unused)]
use k256::ecdsa::{SigningKey, VerifyingKey};
use k256::ecdsa::signature::{Signer, Verifier};
use rand::rngs::OsRng;

fn generate_key_pair() -> (SigningKey, VerifyingKey) {
    let private_key = SigningKey::random(&mut OsRng);
    let public_key = VerifyingKey::from(&private_key);
    (private_key, public_key)
}

fn sign_message(private_key: &SigningKey, message: &str) -> Vec<u8> {
    let signature: k256::ecdsa::Signature = private_key.sign(message.as_bytes()); // explicitly specify as_bytes
    let der_signature = signature.to_der();
    der_signature.as_bytes().to_vec()
}

fn verify_signature(public_key: &VerifyingKey, message: &str, signature: &[u8]) -> bool {
    if let Ok(signature) = k256::ecdsa::Signature::from_der(signature) {
        return public_key.verify(message.as_bytes(), &signature).is_ok();
    }
    false
}

fn main() {
    // Example usage
    let (private_key, public_key) = generate_key_pair();
    let message = "Hello, OP_CHECKSIG!";

    // Signing the message
    let signature = sign_message(&private_key, message);
    println!("Signature: {:x?}\n", signature);

    // Bad message will not verify, only the good message
    let bad_message = "Hello, OP_CHECKSIG bad sig!";

    // Verifying the signature
    let is_valid = verify_signature(&public_key, bad_message, &signature);
    println!("Signature {} is valid: {}",bad_message, is_valid);
    
    // Verifying the signature
    let is_valid = verify_signature(&public_key, message, &signature);
    println!("Signature {} is valid: {}",message, is_valid);
}