the development of metaverse consists of threesuccessive phases from a macro perspective [6]: (i) digital twins,(ii) digital natives, and eventually (iii) surreality,

There are two main families of quantum algo-rithms that are relevant to the current discussion:subgroup-finding algorithms, and amplitude ampli-fication

Quantum computers work by exploiting quan-tum physical effects to decrease the time required tosolve (certain) computational problems by creatingand utilizing quantum superpositions

We finish with a com-parative analysis of these blockchain technologies,in terms of their relative vulnerability to quantumattacks.

Given the strong coupling between data andcryptosystems in blockchains, the potential vulner-ability of these cryptosystems to quantum attacks,the likely introduction of capable quantum com-puters in the mid-term future—not to mention theusual high monetary value of the assets secured byblockchains—it is important to more deeply under-stand their current level of vulnerability.

he US National Institute of Standards andTechnology (NIST) has begun the process of stan-dardizing and deploying quantum-safe public-keycryptography

Doing this, we can confidentlyconclude that by the year 2035 it is more likelythan not that quantum technology will have ad-vanced sufficiently to be able to break RSA2048efficiently. This conclusion is shared by well es-tablished researchers (see, e.g.[2, 3])

It is infeasible to predict the progress and devel-opment of future technology with perfect accuracy.

vulnerable toadvances in quantum technology

n blockchainsthe protected resources cannot easily be decoupledfrom the encryption system being used

If the key, or the de-vice on which it is stored is compromised, or if avulnerability can be exploited, then the data assetcan be irrevocably stolen

If akey is lost, this invariably means that the secureddata asset is irrevocably lost

an always onlinecryptographic system,

s considered the resource—or at least the authoritative description of i

Revoking the key in a timelymanne

Theowner of a resource is by definition the one hold-ing the private encryption keys.

here is nocentral authority to manage users’ access keys

echanisms∗Corresponding authorEmail addresses: jjk30@kent.ac.uk (Joseph J.Kearney ), c.perez@kent.ac.uk (Carlos A. Perez-Delgado)exist to allow the legitimate owner to recover thisaccount.

associated security relies on thedifficulty of factoring, when using RSA, or of thediscrete logarithm problem with EC

Notably, asymmetric encryp-tion schemes such as RSA or Elliptic Curve (EC)cryptography are used to generate private/publickey pairs that protect data assets stored onblockchains