Lightweight keys: Making cryptography sustainable

The fundamental task of cryptography is to take sensitive information and transform it into an unintelligible sequence of characters known as cyphertext. This way it can be transported from one agent to another, and if an intermediate party intercepts it, at least in theory they will not be able to understand it. The transformation must be such that it can later inverted and the information can be recovered. This is an intrinsic weakness: it must be possible to break the cypher. Otherwise it would be no use.


How does encryption work?


The normal way perform encryption is using a combination of a signature algorithm and at least one key: the algorithm takes the key and information to be obscured as input, and produces cyphertext as output after a series of mathematical operations. The receiver must know how to invert the algorithm. This task usually requires the use of a decryption key, which compliments the original encryption key. When asymmetric public-key algorithms are used, the public key is used for encryption and transmitted from the sender to the receiver of encrypted information. This is used by the sender to perform the encryption, and the private key, never shared, is then used to undo the encryption.

Public-key encryption is widely spread, with one of the most used systems being RSA. However it is not without caveats. For example, in many cases it is possible, in theory, to calculate the private key from the public key. Usually it is incredibly hard, and gets exponentially harder with the size of the key used. This is enough to keep things safe under ordinary circumstances (at least while quantum computers are not involved). A simple solution to keep hackers at bay is to use incredibly large encryption keys, to make the mathematics involved in cracking the encryption incredibly hard. How large can must keys be made though?


How big can keys get?


Scientists from the University of Illinois in Chicago, Technische Universiteit Eindhoven and the University of Pennsylvania found that terabyte-sized RSA keys would grant safety even against the most sophisticated quantum computers imaginable. The heavier the keys, the safer the cypher, but the mathematics involved in the encryption and decryption processes become much more complicated. Obviously, computers will be performing these calculations, and they require power to do so. If the calculations are harder and longer, they consume much more energy (this is obvious, for example, when you play a graphics-heavy video game and your computer heats up). Energy consumption has two problems. It can become expensive and has environmental impact. There is also a time cost involved: using larger keys will make the full encryption plus decryption process slower, which can be an impediment to swift communications when necessary. Using larger and larger keys is therefore not viable. In the case of the quantum-proof RSA keys mentioned above, encryption and decryption would take several days, more than most parties can afford to wait for important information.

Therefore, the needs of the user, economic cost and environmental impact must be leveraged when considering the size of an encryption key. They cannot be made indefinitely heavier before becoming unusable for all practical purposes. However, as quantum computing rises, and human ingenuity continues to find ways to challenge cryptography, was alternative is there? RSA and others will fall under quantum computing. Currently, there are some algorithms which are thought to be quantum-proof, but this remains to be proven.


Q1N and sustainable keys


It would be ideal if a safe encryption method could be found which requires only lightweight keys while still offering a secure system for transporting information, or a more efficient way of maintaining a blockchain. Quantum1Net’s quantum encryption key generation (QEKG) system is an example of such a system. The QEKG can generate encryption keys with a single laser assisted by a set of photon detectors and minimal computing power. The encryption keys are randomly generated with little computational overhead. Because of this, they can be discarded after a single use, never to be used again. Even if a key was hacked during its short use-life, this would be wasted effort, as the next communication would be encrypted using a new one.

Vitalik Buterin was recently cited as saying “I would personally feel very unhappy if my main contribution to the world was adding Cyprus’s worth of electricity consumption to global warming”. This is a problem which cryptocurrency is currently facing, and which general cryptography needs to consider. The future of safe, but efficient cryptography depends on creating the most cost-effective encryption system possible. Quantum1Net’s proposal is a step forward in this regard. It promises to revolutionize the world of cryptography as we know it allowing for safe communications with lightweight, and hence eco-friendly encryption keys, minimizing the economic, time and ecological cost of keeping information safe.