Certified Bitcoin Professional Practice Exam

Why is the Bitcoin network considered more secure when more hash power is added?

1. It decreases the transaction speed

2. It makes it easier for miners to find blocks

3. It increases the cost for an attacker to reach over 50% of the global hash rate

4. It simplifies the mining process

The correct answer is: It increases the cost for an attacker to reach over 50% of the global hash rate

The security of the Bitcoin network is heavily tied to its hashing power—measured in hashes per second—which reflects the total computational power being used to mine and process transactions. When more hash power is added, the overall strength of the network increases significantly. This increase in hash power enhances security because it raises the difficulty for potential attackers who might seek to gain control over more than 50% of the network's hash rate, often referred to as a "51% attack." Achieving such control would allow an attacker to double-spend coins and potentially halt transactions, undermining trust in the network. As more miners contribute their computational resources, the cost of securing enough hash power to overpower the majority becomes prohibitively expensive and technologically challenging. Thus, the more hash power there is in circulation within the network, the more secure it is against malicious attempts to manipulate or control the blockchain. In contrast, while effects like the transaction speed or the mining process may change with varying hash power, these do not directly correlate to increased security in the way that the proportional dynamics of hash rate distribution do. Therefore, while other options may touch on impacts related to the network’s operations, they do not address the core issue of how increased hash power makes it more difficult for