The emerging threat of quantum computing poses a significant challenge to blockchain security, as quantum algorithms like Shor's and Grover's could potentially break the cryptographic protections used by cryptocurrencies such as Bitcoin and Ethereum.

While quantum computers capable of decrypting blockchain data are not yet available, experts estimate that milestones in quantum power could be reached in the late 2020s and early 2030s, with some predicting a serious risk before 2030.

Implementing quantum-resistant cryptography in existing blockchain networks faces hurdles, including larger keys and signatures that could slow networks and increase costs, along with political and technical challenges in upgrading decentralized systems.

Some projects, like the Quantum Resistant Ledger (QRL), have already integrated quantum resistance, and Ethereum plans to utilize features like Account Abstraction to enable wallet upgrades without the need for hard forks.

The industry is actively developing Post-Quantum Cryptography algorithms such as CRYSTALS-Dilithium, Falcon, and SPHINCS+, which are being standardized by NIST to resist quantum attacks.

A successful quantum attack could cause systemic failures across the crypto ecosystem, including forging signatures, draining funds from DeFi protocols, and hijacking digital assets, thereby eroding trust in digital ownership.

Given these risks, transitioning to post-quantum cryptography is an urgent priority, and proactive upgrades are essential to safeguard the security and integrity of blockchain systems as quantum computing progresses.

There is ongoing debate about the immediacy of the threat, with some experts like Adam Back estimating a 20-year timeline before quantum computers pose a serious risk, citing current technological and economic barriers.