Ulord public chain pioneered the CryptoHello algorithm to prevent ASIC

Why ASIC makes everyone love and hate it? This has to start with the several innovations of Bitcoin mining equipment and the original intention of blockchain. The development of accounting equipment has gone through three generations, CPU, GPU, FPGA and ASIC. Before introducing the CryptoHello algorithm, let's briefly familiarize ourselves with some basic information of each generation of equipment, so that everyone can have a clearer understanding of the development and evolution of the entire mining ecosystem. (Text: Cyber ​​Kuber)

Introduction to the development of mining equipment

The first generation of equipment, CPU, the Bitcoin system released by Satoshi Nakamoto in 2009 uses the CPU of an ordinary desktop computer for accounting. Satoshi Nakamoto designed Bitcoin mining with the original intention that everyone can participate in accounting, and set the accounting threshold to a very low level. The idea of ​​decentralized computing power also started at that time. If we compare the decentralized thinking of Bitcoin with the implementation process of accounting, they are completely unified. However, as the influence of Bitcoin continues to increase and the price continues to rise, the market began to think about how to gain more benefits in the process of this competitive accounting process, so the accounting equipment is quietly upgraded.

The second generation is equipped with GPU. GPU is not unfamiliar to many people. It is a necessary graphics card for computers. Driven by huge demand, it began to appear in 2011 and replaced CPU for mining. Compared with CPU, GPU speed is much higher. In the development of GPU mining, Bitcoin has gradually shown signs of inequality. With the continuous increase in demand for GPU, the price of GPU has also risen. Compared with the fairness of the CPU era, the threshold has been raised too much.

The third generation equipment is FPGA and ASIC. FPGA is field programmable gate array. Its advantage lies in programmability, which provides a feasible solution for reducing design costs. Compared with computer CPU and GPU, the era of FPGA mining is particularly short, only about half a year. Because it appears as a semi-custom circuit in the field of application-specific integrated circuits (ASIC), it can be regarded as an ASIC chip testing solution. Compared with GPUs of the same period, FPGA has similar performance and price, but its relatively low power consumption is one of its advantages.

In 2012, FPGA was popular for about half a year. In the second half of the year, ASIC chips based on FPGA began to be trial-produced, such as Pumpkin Zhang, Shenzhen Baked Cat, etc. ASIC is a dedicated integrated circuit with faster execution speed than FPGA. It is tailor-made and can save the redundant logic implementation of FPGA, so the cost is lower than FPGA. There are many similarities between the implementation forms of FPGA and ASIC mining equipment. FPGA is more general, while ASIC is more customized. The picture below is the first generation Avalon chip of Pumpkin Zhang 110nm process.

Some explorations into anti-ASIC in the industry

As we can see, with the continuous improvement of production technology, Bitcoin mining has gradually entered a terrifying arms race, mining has become more and more professional, and it is difficult for the general public to participate. This situation has led to the increasing centralization of the mining industry, which is contrary to the original concept of Satoshi Nakamoto's design of Bitcoin.

Of course, in the process of mining centralization, some teams advocating universal participation have also made their own efforts and explorations to prevent the situation from getting worse. In the first half of 2013, Litecoin exploded the market with its scrypt algorithm that resisted professional ASIC mining machines. But in fact, the scrypt algorithm (similar to Memorycoin, Litecoin, Yacoin) did not meet market expectations by using large memory requirements to resist ASICization. With the increase in LTC unit prices, LTC's ASIC chip was designed at the end of the year. Another example is Dash's X11 algorithm, etc. The serial algorithm design idea attempts to prevent ASICization but is powerless. As long as the currency value reaches the investment in supporting mining hardware, technically feasible solutions will be proposed and put into production.

Introduction to CryptoHello Algorithm

Does the blockchain that advocates decentralization really need to appear in another centralized way? Just when we were confused, an algorithm came into our view, that is today's protagonist CryptoHello algorithm. Theoretically speaking, the cost of manufacturing ASIC of this algorithm is very high. Its appearance has brought a glimmer of hope to the mining industry shrouded in the haze of centralization.

The CryptoHello algorithm draws on the design ideas of the memory-hard proof-of-work algorithm, combines the characteristics of CPU, GPU, ASIC and other architectures, and optimizes it for the CPU architecture. The method is divided into three stages: initializing the working memory with a pseudo-random sequence, modifying the working memory, and generating the final result based on the content of the working memory. As shown in the following figure:

1. Initialize the working memory

Use the SHA3 function to calculate the input and initialize the linear congruential pseudo-random number generator seed. Fill the working memory continuously in units of K blocks (32 bytes per block), where the first K-1 blocks are generated by the pseudo-random number generator, and the last block is filled by randomly selecting one of the hash function families (16 different hash functions) based on the previously filled content, and the random number generator seed is updated. As shown in the following figure:

2. Modify the memory

First, the SHA3 function is used to generate the seed of the random number generator based on the last block of the working memory, and the state variable with a length of L bytes is initialized. Then C main loops are performed, and 64L sub-loops will be performed in each main loop. In each sub-loop, a pair of addresses will be generated by the random number generator, and the byte data of the two addresses in the working memory and the byte data in the state vector will be merged and exchanged using the XOR method to update the contents of the memory and the state vector. After the sub-loop ends, the function of the hash function family will be used to update the state vector and reinitialize the random number generator seed. According to the existing parameter design, one quarter of the content of the working memory will be modified.

3. Results

The main purpose of this step is to quickly generate the final result based on the content of memory M. The content of d blocks in the continuous XOR random memory (d depends on the result of the last one-way function) is updated using the hash function family, and d is recalculated until the last block of the working memory. Finally, the SHA3 function is used to form the final result. The second and third steps are shown in the figure below:

The design of the CryptoHello algorithm is obviously "unfriendly" to GPUs and ASICs. First, the working memory capacity is optimized for the CPU's cache capacity, but it is difficult for GPUs or ASICs to meet the memory capacity requirements of executing a large number of proof-of-work algorithms at the same time. Second, the algorithm limits parallel efficiency in two ways. One is to use a hash function family consisting of 16 hash functions and randomly select execution from them. The other is to use a strictly serial execution sequence in the working memory modification stage, and access in bytes. Finally, the control logic of the entire scheme is complex, the required memory capacity is large, and the memory access address is irregular, making it difficult to implement ASIC using the traditional method of stacking a large number of acceleration component modules.

The CryptoHello algorithm was first adopted by the Ulord team in the Ulord peer-to-peer value transfer public chain. The purpose is to limit the centralization of mining through algorithms, which reflects the value concept of the R&D team of openness and freedom, advocacy of fairness, and respect for creation. Although the CryptoHello algorithm has "taken great pains" to limit algorithm ASICs, the development of hardware is closely related to market demand. With the continuous increase in the market value of Ulord, whether the CryptoHello algorithm can stand the test, let us wait and see!

On May 22, 2018, the Ulord public chain launch conference with the theme of "Technology Craftsmanship, U-You Co-creation" was grandly held at the Diaoyutai State Guesthouse in Beijing. Hou Yunchun, former deputy director of the Development Research Center of the State Council, Pan Zhenzhou, former vice minister of the Ministry of Culture, Liu Yunjie, academician of the Chinese Academy of Engineering, Liu Qiaoyi, former political commissar of the School of Computer Science of the National University of Defense Technology, Chang Limin, member of the Party Working Committee of the National Changsha Economic and Technological Development Zone, Yi Lihua, founder of Lede Capital, and Nam Taek-hyun, CEO of South Korean comprehensive entertainment media company THE E&M, and other scholars, investors, partners and guests attended and delivered speeches.

Dr. Tan Lin, CEO of Ulord, said that the Ulord public chain is an open, shared, secure and reliable underlying operating system in the content field, and a set of blockchain underlying architecture and digital resource distribution protocols. Based on Ulord, third-party developers can create various blockchain applications, such as social tools, live video, original content platforms and even e-commerce services. In this way, a complete ecosystem of blockchain technology and applications can be jointly built, and the value sharing of blockchain technology can be truly realized.

(Author: Cyber ​​Kuber)

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