Method isChainValid

src/blockchain.js:300–329

* Loops over all the blocks in the chain and verify if they are properly * linked together and nobody has tampered with the hashes. By checking * the blocks it also verifies the (signed) transactions inside of them. * * @returns {boolean}

()

   * @returns {boolean}
   */
  isChainValid() {
    // Check if the Genesis block hasn't been tampered with by comparing
    // the output of createGenesisBlock with the first block on our chain
    const realGenesis = JSON.stringify(this.createGenesisBlock());

    if (realGenesis !== JSON.stringify(this.chain[0])) {
      return false;
    }

    // Check the remaining blocks on the chain to see if there hashes and
    // signatures are correct
    for (let i = 1; i < this.chain.length; i++) {
      const currentBlock = this.chain[i];
      const previousBlock = this.chain[i - 1];

      if (previousBlock.hash !== currentBlock.previousHash) {
        return false;
      }

      if (!currentBlock.hasValidTransactions()) {
        return false;
      }

      if (currentBlock.hash !== currentBlock.calculateHash()) {
        return false;
      }
    }

    return true;
  }
}

module.exports.Blockchain = Blockchain;