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mercoledì 20 novembre 2019

Ready for the Post-Quantum, a threat to the current cryptography

Although the end user should not worry about whether the technology is quantum resistant or not, it is the industry and blockchain experts who should prepare . . . before it gets too late!
A few weeks ago Google announced a turning point in quantum computing: the company in Mountain View would reach “quantum supremacy”, creating in fact a computer able to complete calculations, which even the fastest supercomputer in the world could not replicate.
Unlike normal computers, quantum computers use qubits: as the classic bit allows two states, state 0 and state 1, so qubits does, but thanks to the superposition principle, it is possible to combine linearly the two states, increasing exponentially the power and speed of these computers.
PREMISE
In Blockchain encryption it is rather difficult (not to say impossible) to calculate the value of a private key, having only the public one available.

To do this you should “simply”solve a problem called Elliptic Curve Discrete Logarithm, but you would need a supercomputer that would take a long time (millions of years) to process and solve it.
On the contrary, a quantum computer would be able to decipher the key in a very short time, making the cryptographic environment of the whole blockchain (and not only) obsolete, and performing the calculation in less than 10 minutes.
The problem of quantum computing is not a novelty for cryptography, we have been talking about it for a long time and the “competition” to develop a Post-Quantum technology continues to cause debate within companies and experts.
Some people venture that a quantitatively resistant computer technology could be available within 5 years, however in the blockchain field there are already some concrete examples of technologies, ready for Post — Quantum.
IOTA for example is among the most interesting projects regarding Post–Quantum. The foundation says that Tangle is safe and prepared against post-quantistic encryption, because its tangle is a “flow of interconnected and individual transactions”, structured in such a way as to make difficult even the crack by a quantum computer.
Through the module “Masked Authenticated Messaging”, the blockchain can get to “encrypt entire streams of data, fixing them not only securely in the IOTA tangle, but also in a quantum way”.
TAKAMAKA Post-Quantum
Being Post-Quantum does not simply mean that bits have increased in the algorithms used, on the contrary here it is adopted a totally different approach to the rule of the known attacks.
In the case of Takamaka, the block signature algorithm is qTesla, while for the transaction signature it is used ED25519 (High-speed high-security signatures): it is a public key system, carefully designed for different levels of verification and implementation, useful to achieve very high speeds without
compromising security.
Although this signature does not fall into the category of Post-Quantum, there is still no computer able to compromise it. However, when this occurs, a post-quantum is expected to be replaced immediately.
The change of encryption is already covered, supported and implemented in the Takamaka protocol. The problem does not arise for transactions that will already be included before this step, since they are covered by the “envelope qTesla” and by the hash sha3–512, both quantum-proof.
The reason why Takamaka does not immediately apply qTesla to transactions, is mainly due to the size that the signature generates (about 14kb), because it would affect rather significantly the size of the transaction: 600bytes.
CONCLUSION
Surely there is too much at stake: quantum computers may soon be able to decipher all encrypted information, including bank accounts and government databases. For cryptographers — the cryptocurrency - and the blockchain, time is of the essence.
Links and references
To view the white paper and technical documents, please visit www.takamaka.io Stay Tuned.
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