Blockchain has been heralded in terms of security — especially as a way to bring together people who may not trust each other all that much in the first place. For example, blockchain has been described as nearly impenetrable technology, which can be used to protect data from cyberattacks and improve cybersecurity across industries. Designers of blockchain state how three factors deliver the desired level of security: decentralization, cryptography and consensus. More specifically it is the complex interplay of these characteristics that secure blockchain transactions and discourage attack.
The security feature of blockchain is based on a combination of public and private keys. These keys are formed by various combinations of random numbers and letters, and these codes are not directly associated with users’ identity. Through the keys the need for weak and easily compromised passwords and online identities is avoided.
However, blockchain may not be as secure as proponents think, according to Aleksey K. Fedorov, Evgeniy O. Kiktenko and Alexander I. Lvovsky, writing in the science journal Nature. The authors predict that in less than ten years the emerging generation of quantum computers will be able to break a blockchain’s cryptographic codes. Quantum computers leverage different physical phenomena — superposition, entanglement, and interference — to manipulate information.
The vulnerability with blockchain arises because the technology relies on ‘one-way’ mathematical functions. These functions are relatively straightforward to run on a conventional computer and they are difficult to calculate in reverse. However, quantum computers will be able to calculate the one-way functions easily and this will render one-way functions obsolete.
In fact, the researchers argue, a blockchain with its single digital signature will be easier to crack by a quantum computer than a user with a bank account who has multi-layer processes like plastic cards, security questions, identity checks and the involvement by human cashiers.
To avoid the crash of the expanding cryptocurrency market, the researchers recommend, quantum-safe encryption needs to be developed instead – using quantum computers. This arises because quantum states cannot be copied or measured without being altered, and any alteration will immediately alert the user.
