Ed25519 Digital Signatures

/**
 * Generates Ed25519 keypair from seed
 * @param seed - 32-byte seed as Uint8Array
 * @returns 64-byte keypair as Uint8Array (32-byte secret key + 32-byte public key)
 */
function ed25519KeypairFromSeed(seed: Uint8Array): Uint8Array;

import { waitReady, ed25519KeypairFromSeed } from "@polkadot/wasm-crypto";

await waitReady();

const seed = new Uint8Array(32).fill(1); // Example seed
const keypair = ed25519KeypairFromSeed(seed);

const secretKey = keypair.slice(0, 32);
const publicKey = keypair.slice(32, 64);

console.log("Secret key length:", secretKey.length); // 32
console.log("Public key length:", publicKey.length); // 32

/**
 * Signs a message using Ed25519
 * @param pubkey - 32-byte public key as Uint8Array
 * @param seckey - 32-byte secret key as Uint8Array
 * @param message - Message to sign as Uint8Array
 * @returns 64-byte signature as Uint8Array
 */
function ed25519Sign(pubkey: Uint8Array, seckey: Uint8Array, message: Uint8Array): Uint8Array;

import { waitReady, ed25519KeypairFromSeed, ed25519Sign } from "@polkadot/wasm-crypto";

await waitReady();

const seed = new Uint8Array(32).fill(1);
const keypair = ed25519KeypairFromSeed(seed);
const secretKey = keypair.slice(0, 32);
const publicKey = keypair.slice(32, 64);

const message = new TextEncoder().encode("Hello, Ed25519!");
const signature = ed25519Sign(publicKey, secretKey, message);

console.log("Signature length:", signature.length); // 64

/**
 * Verifies Ed25519 signature
 * @param signature - 64-byte signature as Uint8Array
 * @param message - Original message as Uint8Array
 * @param pubkey - 32-byte public key as Uint8Array
 * @returns true if signature is valid, false otherwise
 */
function ed25519Verify(signature: Uint8Array, message: Uint8Array, pubkey: Uint8Array): boolean;

import { 
  waitReady, 
  ed25519KeypairFromSeed, 
  ed25519Sign, 
  ed25519Verify 
} from "@polkadot/wasm-crypto";

await waitReady();

const seed = new Uint8Array(32).fill(1);
const keypair = ed25519KeypairFromSeed(seed);
const secretKey = keypair.slice(0, 32);
const publicKey = keypair.slice(32, 64);

const message = new TextEncoder().encode("Hello, Ed25519!");
const signature = ed25519Sign(publicKey, secretKey, message);

const isValid = ed25519Verify(signature, message, publicKey);
console.log("Signature is valid:", isValid); // true

// Test with wrong message
const wrongMessage = new TextEncoder().encode("Wrong message");
const isInvalid = ed25519Verify(signature, wrongMessage, publicKey);
console.log("Wrong message signature is valid:", isInvalid); // false

import { 
  waitReady, 
  ed25519KeypairFromSeed, 
  ed25519Sign, 
  ed25519Verify 
} from "@polkadot/wasm-crypto";

async function demonstrateEd25519() {
  await waitReady();
  
  // Generate keypair from seed
  const seed = new Uint8Array(32);
  crypto.getRandomValues(seed); // Use random seed in production
  
  const keypair = ed25519KeypairFromSeed(seed);
  const secretKey = keypair.slice(0, 32);
  const publicKey = keypair.slice(32, 64);
  
  // Sign multiple messages
  const messages = [
    "First message",
    "Second message",
    "Third message"
  ];
  
  const signatures = messages.map(msg => {
    const msgBytes = new TextEncoder().encode(msg);
    return ed25519Sign(publicKey, secretKey, msgBytes);
  });
  
  // Verify all signatures
  const verifications = messages.map((msg, index) => {
    const msgBytes = new TextEncoder().encode(msg);
    return ed25519Verify(signatures[index], msgBytes, publicKey);
  });
  
  console.log("All signatures valid:", verifications.every(v => v)); // true
  
  return { keypair, signatures, verifications };
}

demonstrateEd25519();