By exploiting its higher processing capacity to defeat the encryption that safeguards private keys and transactions on the Bitcoin network, a quantum computer could theoretically hack Bitcoin. However, the current state of quantum technology is not yet advanced enough to pose a significant threat to Bitcoin’s security.

Quantum computers might make public-key cryptography less secure because of their capacity to answer some mathematical problems far more quickly than classical computers. For example, Shor’s algorithm — a quantum algorithm — can factor large integers exponentially faster than classical algorithms. Factoring large integers is the basis of many public key encryption schemes, including the one used in Bitcoin.

The public-key cryptography employed in Bitcoin and other cryptocurrencies might hypothetically be cracked if a quantum computer had the processing capability to carry out Shor’s algorithm. An attacker with a quantum computer could potentially steal BTC by computing the private key corresponding to a public key used to receive Bitcoin. The big prime numbers used to generate the public-private key combination could be factored in to achieve this.

However, it is crucial to remember that quantum computing is still in its infancy and lacks the power to carry out Shor’s algorithm at the scale necessary to decrypt Bitcoin. Although small-scale quantum computers have been shown to factor in small numbers, there is still a long way to go before a large-scale quantum computer that breaks Bitcoin’s encryption can be built.

In addition, the Bitcoin network is constantly developing to counter possible security risks, such as the risk presented by quantum computers. For instance, a hash-based signature system like the Lamport signature method might make Bitcoin more resilient against quantum attacks. Researchers are also investigating the use of post-quantum cryptography, which was created to be resistant to quantum computers.

The Lamport signature method is considered one of the post-quantum cryptographic methods that can be used to secure digital signatures from potential threats from quantum computers. This technique generates several pairs of public and private keys to verify digital signatures using a one-time hash function. 

The communication is protected against efforts at quantum hacking since each pair is used to sign a distinct section of the message. Due to the one-time nature of the hash function, even if an attacker gets hold of one of the private keys, they cannot use it to forge other signatures or find the other private keys.