Quantum Blockchain: Opening the Door to New Risks and Opportunities

Quantum blockchain is a growing area in quantum cryptography that has recently seen significant progress in academic and open source communities. The primary goal of quantum blockchain is to achieve an advancement of the quantum networking primitives — that have been theorized, designed and experimentally demonstrated in academic and national labs — to a scalable network scheme that will be adaptable to the public networking environment, which is primarily classical.

The classical blockchain was introduced as a step in a progression from the earlier, less peer-oriented and more centralized network schemes to the more peer-oriented grids and cloud architectures. As the classical networking schemes progressed, and higher degrees of access and control became available to more and more users, a series of simplifications of the access and control mechanisms took place, so as to make the cloud more user-friendly for its broad audience. The user-friendliness that was introduced was synonymous with a lack of visibility into network mechanisms.

Classical blockchain is largely a reaction to this effect, which is why it first became popular among a relatively tech-savvy demographic. This demographic also has a particular desire for sovereignty over their information, including over their identifying information.

Quantum blockchain’s origins are different than the classical blockchain’s in that quantum blockchain is being introduced when its preceding quantum network technology is largely in a pre-implementation and pre-commercialization phase. Quantum blockchain is assumed to be a natural direction for the quantum internet, since the quantum internet is primarily inspired by the historical progression of the classical internet. Quantum blockchain does not need to be designed in a reactionary fashion, however, since the problems that the classical blockchain reacted to do not yet exist in the quantum internet.

An effect that the designers and implementers of quantum networking technology ought to be sensitive to is the inadvertent re-creation of the issues with the classical internet, as a sort of back-reaction on the underlying quantum networking technology. Information-theoretic security is an ideal that most quantum communication researchers strive to achieve in their designs. Many practical considerations are however often either taken for granted or ignored in this theoretical work.

Complete information-theoretic security may be impossible to implement in any practical setting. So, the quantum internet should be designed with a focus on the users and their particular context, with all its particular risks and opportunities. Users should not be peripheral considerations which fit into a framework that is primarily designed for information-theoretic beauty, or don’t. Users should also not be babied or hand-held in the way that they were by the classical internet. This defines a challenge for us: to find a balance between accommodating all of a users’ particular needs and contexts, and enabling them to communicate with a broader community in a way that is always sufficiently secure for their purposes.

A phenomenon that has enabled the fantastic and rapid advancement of classical cloud computing is the infrastructure-as-code mentality. This was effectively a shift in the way that networks are maintained, introduced by automation. Network automation, like the classical blockchain, arrived “late to the game” in the sense that it evolved out of an existing classical internet’s limitations. The designers of quantum networks should be aware that the same automation will inevitably be applied to anything and everything that is released from their labs, and plan ahead for this. What humans refuse to do on their own, software will inevitably do for them in an automatic fashion. Who do we want to define the topology of the network? Humans, code, or both? In the case of the classical internet, the abstract interfaces for defining network topology gives the impression that users have their own locally configurable networks, when in fact the nodes in each of these networks are not “local” to any given user, but are sitting side-by-side in any and every permutation in the large centralized data centers of hosting companies. This messy reality is actually a clever resolution of the set of codes that define each user’s desired network architectures. This is not necessarily a bad thing, but these details are what inspired classical blockchain.

Classical blockchain reacts to this by distributing data to all its nodes, which may actually be local to a user if they so desire. Rather than affording users a nice software description of infrastructure, they are afforded the assurance that their data is their own (with certain computational assumptions). The user’s software is no longer hiding a messy reality, but equivalently the user no longer has the ability to control network topology through software. The network topology is also entirely flat, meaning that each user is a peer, which leads to the duplication of data and irresponsible inefficiency in the design of most blockchains.

A balance exists between duplicating and localizing the information of the entire network redundantly at each node, and singularly localizing the information in a centralizing location. Overall, the classical internet currently embodies a tug-of-war between those companies which offer centralized services and wage war for users’ trust, and the reaction to that entire trust-based framework which is “trustless” blockchain technology.

Within this tug-of-war, users decide where and when each victory is had. They decide this much in the way that consumers decide which companies prevail among market forces in the economy. In the increasingly virtual world, users are becoming more and more dependent on the convenient abstractions of software that the internet presents them. From researchers, to developers, to consumers, the trend is that people are following signifiers more than utilizing affordances. This means that users are deciding on what bodies they will and will not trust with their information, loyalty, etc. without any truly relevant information. Many people recognize this and flee to the trustless world of the blockchain. Is this healthy?

Communication technology is not just technology. It is both an outcome of and a shaper of people’s desires and livelihoods, more-so now than ever. Designers of network technology must ask themselves: is this a healthy mode of communication? Who will be the early adopters? Why? When performing security analyses, don’t just ask how much information will quantitatively be leaked, but ask what social implications there are for this interaction topology.

Many people have expressed discontent with the lack of substance that there is in the requests that services make for users’ trust in our age. Blockchain technology generally starts from the opposite extreme, of a trust vacuum. It must be acknowledged by any communication technology that trust needs to be earned authentically. Technologists should look to the social sciences, and attempt to emulate the characteristics or healthy, thriving communities. This requires that researchers become generalists. This is a lot more work than any given course of study, or employer, will typically require of a researcher, designer or implementer of technology. It is however one of the most important issues currently facing our world, and it is within our reach to participate in solving it in a meaningful way. Rather than emulating the classical internet with the quantum internet, we should learn from our mistakes by making intentional and meaningful improvements. We will succeed when individuals take personal responsibility for themselves and their work at every level. There is nothing more worthwhile to do than that, and that is how trust is truly earned.