Aug 2, 2018 · 6 min read

InterValue aims to provide a global value Internet infrastructure. In response to deal with various problems that existing in the present blockchain infrastructure, InterValue optimizes the protocol and mechanism of blockchain technology at all levels, which can achieve the support agreement of value transmission network. At present, the InterValue 2.0 testnet has been released, we designed and implemented a new HashNet consensus mechanism. Transaction speed within one single shard exceeds 280,000 TPS and 4 million TPS for the whole network. Security (anti-quantum attack characteristics) is undoubtedly the highlight of InterValue under the goal of establishing a low-level infrastructure for the whole field of ecology.

What is the quantum attack?

Quantum computing is a new way of building computers — using the quantum properties of particles to perform operations on data, it is probably the same way as traditional computers. In some cases, the amount of algorithmic acceleration is unusual. It is this characteristics that makes some difficult problems that exist in the electronic computer environment become easy to calculate in the quantum computer. This superior computing power of quantum computers has influenced the security of existing public key cryptography which based on computational complexity. This is the quantum attack.

What does anti-quantum attack mean?

Algorithms have always been the underlying core of blockchain technology. Most of the current algorithms are unable to withstand quantum attacks. It means that all the information of the user will be exposed to the quantum computer. If you have an anti-quantum attack algorithm, it means that the personal information is safe, at least with current technology, it cannot be cracked. Anti-quantum attack algorithms mean security. The impact of quantum attacks on digital currencies is devastating. Quantum attacks directly disrupt existing information security systems. Quantum attacks will expose the assets in the digital industry, including the benefits of mining; the keys to your wallet will be cracked and the wallet will no longer be secure. Totally, the existing security system will be disintegrated. Therefore, it is imperative to develop anti-quantum attack algorithms in advance. It is a necessary technical means to firmly protect the privacy of users.

InterValue uses a new anti-quantum attack cryptographic algorithm at the anti-quantum attack level. By replacing the ECDSA signature algorithm with the NTRUsign signature algorithm that based on the integer lattice, and replacing the existing SHA series algorithm with the Keccak-512 hash algorithm, the speed, and threats of the rapid quantum computation decrease.

Adopt NTRUsign digital signature algorithm

Current ECDSA signature algorithm

The current blockchain mainly uses the ECDSA digital signature algorithm based on elliptic curve. The signature algorithm: First, the public-private key pair needs to be generated, the private key user keeps it, the public key can be distributed to other people; secondly, the private key pair can be used and a specific message is signed; finally, the party that owns the signature public key is able to verify the signature. ECDSA has the advantages of small system parameters, fast processing speed, small key size, strong anti-attack and low bandwidth requirements. However, the quantum computer can implement a very efficient SHOR attack algorithm by ECDSA signature algorithm, and the ECDSA signature algorithm cannot resist the quantum attack.

Adopt new NTRUsign-251 signature algorithm

At present, the public key cryptosystem against quantum SHOR algorithm attacks mainly includes public key cryptography that based on lattice theory, code-based public key system represented by McEliece public key cryptosystem and multivariate polynomial represented by MQ public key cryptography. The security of McEliece public key cryptosystem is based on the error correction code problem, which is strong in security but low in computational efficiency. The MQ public key cryptosystem, that is, the multivariate quadratic polynomial public key cryptosystem, based on the intractability of the multivariate quadratic polynomial equations on the finite field, has obvious disadvantages in terms of security. In contrast, the public key encryption system based on lattice theory is simple, fast, and takes up less storage space. InterValue uses the signature algorithm based on the lattice theory NTRUSign-251. The specific implementation process of the algorithm is as follows:

It has been proved that the security of the NTRUSign-251 signature algorithm is ultimately equivalent to finding the shortest vector problem in a 502-dimensional integer lattice, but the SHOR attack algorithm for the shortest vector problem in the lattice is invalid, and there is no other fast solutions under the quantum computer. The best heuristic algorithm is also exponential, and the time complexity of attacking NTRUSign-251 signature algorithm is about 2168. Therefore, InterValue uses NTRUSign-251 algorithm that can resist SHOR algorithm attack under quantum computing.

Adopt Keccak512 hash algorithm

The common anti-quantum hash algorithm

The most effective attack methods for hash algorithm under quantum computer is GROVER algorithm, which can reduce the attack complexity of Hash algorithm from O (2^n) to O (2^n/2). Therefore, the current bit adopts the Hash algorithm PIREMD160 whose output length is only 160 bits, under this circumstance, quantum attacks algorithm used in the currency system is not safe. An effective way of resisting quantum attacks is to reduce the threat of the GROVER algorithm by increasing the output length of the Hash algorithm. It is generally believed that the Hash algorithm can effectively resist quantum attacks as long as the output length of the hash algorithm is not less than 256 bits. In addition to the threat of quantum attacks, a series of hash functions that are widely used in practice, such as MD4, MD5, SHA-1, and HAVAL, are attacked by traditional methods such as differential analysis, modulo difference, and message modification methods. Therefore, blockchains’ Hash algorithm also needs to consider the resistance of traditional attacks.

Winning the hash algorithm Keccak512

Early blockchain projects such as Bitcoin, Litecoin, and Ethereum used SHA series Hashing algorithms that exist design flaws (but not fatal). Recently, new blockchain projects have been adopted by the National Institute of Standards and Technology. The SHA-3 plan series algorithm is a new Hash algorithm.

InterValue adopts the SHA-3 plan’s winning algorithm Keccak512, which contains many latest design concepts and ideas of hash function and cryptographic algorithm. It is simple in design, which is convenient for hardware implementation. The algorithm was submitted by Guido Bertoni, Joan Daemen, Michael Peters, and Giles Van Assche in October 2008. The Keccak512 algorithm uses a standard sponge structure that maps input bits of arbitrary length into fixed-length output bits. The speed is fast, with an average speed of 12.5 cycles per byte under the Intel Core 2 processor.

As shown in the figure, in the absorption phase of the sponge structure, each message packet is XORed with the r bits inside the state, and then encapsulated into 1600 bits of data together with the fixed c bits to perform the round function f processing, and then into the squeeze. In the extrusion phase, a hash of n-bit fixed output length can be generated by iterating 24 cycles. Each loop R has only the last step round constant, but the round constant is often ignored in collision attacks. The algorithm proved to have good differential properties, and until now third-party cryptanalysis did not show that Keccak512 has security weaknesses. The first type of original image attack complexity for the Keccak512 algorithm under quantum computer is 2²⁵⁶, and the second type of original image attack complexity for the Keccak512 algorithm is 2¹²⁸, so InterValue combined with the Keccak512 algorithm can resist the GROVER algorithm attack under quantum computing.

Written in the end

Quantum computing has gone through 40 years from the theory to practice. From the emergence to the present, it has entered the stage of quantitative change to qualitative change in technology accumulation, business environment, and performance improvement. For the blockchain, the most deadly part is not investor’s doubt, but the accelerated development of quantum computers. In the future, quantum computers are most likely to subvert the traditional technical route of classical computing and have a larger field of development. We are sympathetic to its destructive power to the existing blockchain, and we look forward to helping the entire blockchain industry to shape a new ecosystem. On the occasion of entering the new “quantum era, trusting society”, the InterValue team believes that only by fully understanding the essence of quantum cryptography (quantum communication) and anti-quantum cryptography, can we calmly stand on a high level and arrange the outline.


World's first support million TPS practical blockchain 4.0 project, a highly practical decentralized distributed application development platform .


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World's first support million TPS practical blockchain 4.0 project, a highly practical decentralized distributed application development platform .

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