Transaction.js

const { Wallet } = require("./Wallet");
const Transaction = (exports.Transaction = class Transaction {
  constructor(opts = {}) {
    Object.assign(
      this,
      {
        from: null,
        to: null,
        value: 0,
        nonce: 0,
        signature: null,
      },
      opts
    );
  }

  hash() {
    const head = JSON.stringify(this, ["from", "to", "value", "nonce"]);
    return createHash("SHA256").update(head).digest("hex");
  }

  sign(privateKey) {
    const cert = Wallet.getNodePrivateKey(this.from, privateKey);
    const signature = createSign("SHA256")
      .update(this.hash())
      .sign(cert, "hex");
    return new Transaction({ ...this, signature });
  }

  test() {
    const cert = Wallet.getNodePublicKey(this.from);
    const signature = createVerify("SHA256").update(this.hash());
    if (!this.from || !this.signature) return false;
    return signature.verify(cert, this.signature, "hex");
  }
});