Anonymity of Past and Present: From Parchment to Blockchain Cryptography

Anonymity: Cryptography technology designed to protect personal privacy

1. Definition

Anonymous, as the name suggests, is to hide some information during the transaction, usually including partial anonymity and complete anonymity. Anonymous currency is a popular type of pass in the blockchain industry. It refers to a special blockchain pass that hides the transaction amount and current account information during the transaction process.

2, type

● Partially anonymous

Partially anonymous, that is, hiding part of the transaction information. There are two main categories: anonymous restrictions and partial information anonymity.

Anonymous restrictions mean that for a given organization, part of the transaction is displayed, while for other users, all transaction information is hidden.

Partial information anonymity refers to hiding part of the transaction information, which may be one or more of an account, a transaction process, and a transaction account.

● completely anonymous

That is to say, all data, transaction amounts and processes in the process before and during the transaction are not disclosed, and have almost completely anonymous digital asset characteristics.

3, the main purpose

Anonymous transactions are currently mainly used for commercial applications, including competitive bidding, large money transfers, and other high-privacy business activities.

4, the main technical principles

5. The necessity of anonymous currency

A long time ago, as a password punk community that included most of the world's IT elites, it has been trying to develop anonymous currency. The reason is that traditional money and payment methods rely on third-party governments and banks for credit endorsement, and each user involved in the payment requires real-name system, including authentication by bank card and ID, especially with the era of big data. When it comes, everyone is transparent in front of the data, which makes many people feel that their privacy has been violated. This is also the reason why digital assets such as Bitcoin are gradually appearing in the public's field of vision, because their addresses do not bind user identity information, nor do they require real-name authentication, so they can protect part of personal privacy.

But with the deepening of Bitcoin's openness, its anonymity began to show some limitations of its existence . Including the traceability of the online transaction address, the transaction address and transaction record associated with an address will be exposed; and the offline transaction will associate the wallet address with the real identity to query all transaction records of both addresses. In addition, although there are many third-party providers that provide a coin service to help anonymity, it is equivalent to anonymity restrictions and has limited effectiveness.

Second, the evolution of development: from parchment to password machine

1. Overview of cryptography

Cryptography, as the name implies, protects the content and information. According to Wikipedia's interpretation, the term cryptography originated in Greek and was produced as early as 400 BC. It is a discipline that specializes in confidential communications and protects the transmission of information to prevent third parties from stealing information, including cryptography. Learning and cryptanalysis are mainly divided into classical cryptography and modern cryptography. Of course, if you look at the time period of intensive use of cryptography during the war, you can also use modern cryptography as a time division in modern cryptography.

2. The development of cryptography

● Classical cryptography

Classical cryptography mainly uses text substitution to achieve confidentiality. The earliest practical application can be traced back to the Caesar cipher in Roman times in 60 BC. At that time, Caesar, as the Roman consul, knew the importance of the confidentiality of the core military information to a battle. Caesar designed a conversion text specifically for military use, mainly using a single-table replacement encryption technology, namely in plain text. All letters move forward or backward several times in the alphabet, so even if the information is obtained by the enemy, it is not necessarily understandable. This is the earliest password case used for practice, and is also the famous Caesar password .

Although Caesar's enemies did not realize this encryption at the time, but later there were certain restrictions on the letter shift, and the improved random shift alphabet was easier to crack in a certain background, and later turned around with Scotland. The Queen’s tragedy came to an end.

In addition to the famous Caesars password, there are five other classical encryption methods, including:

● Modern cryptography

Modern cryptography can be seen as part of modern cryptography, but it is divided in time to separate the wars from the use of cryptography.

When talking about modern cryptography, I have to talk about the Vigenal password . Although the Vienner code was designed in 1586, it was not until 200 years later that Morse code became popular, and the password began to enter people's field of vision. Therefore, it is understandable to incorporate it into modern cryptography according to the period of its application. Once, Vigenal's "Password Theory" was also called the "unbreakable" code, and was deciphered by Charles Babbage, who was founded in 1854 by the modern computer theory framework.

It’s also thanks to a dentist who was lucky enough to get a patent. If he didn’t repackage the Vienner password at the time, and it’s difficult to crack the password, then the Vienner password might take about 10 years. Can be deciphered by Cassisky. During the American Civil War, the Southern Coalition had been using the Vienner code. Although it had already been deciphered, the Northern Government had always occupied the advantage of intelligence acquisition because it was not published on a large scale. The Genar password was not deciphered at the time, and maybe the time between the North and the South will be longer.

Modern cryptography is frequently used or during World War II. In 1918, at the end of World War I, the German Arthur Shelbyus designed a cryptographic machine with reference to Koch's idea, which was later known as Enigma. Enigma is a multi-table replacement encryption practice with an encryption core of 3 wheels. The outer edge of each wheel is written with 26 German letters to indicate 26 different positions, and the connection between the different wires inside the wheel changes the position of the input and output to encrypt. A 3-wheel Enigma machine that can perform different encryption changes in 17576. Enigma was the most advanced cipher machine of the German Army, Air, and Air Forces in World War II. It was once unstoppable in the early period of World War II. At that time, Enigma made some changes to the original form that was just designed. It used three regular wheels and one reflection wheel, which greatly improved the security of military information.

But in 1939, when World War II was just kicked off, Polish cryptographers Marian Reyevsky, Gerz Rozowski and Henrik Zogarski shared the results of Deigma's research to British allies. Helped a lot. However, in the cryptographic wars between Germany and Poland and the United Kingdom, there are two people we can't ignore. One is the British code-breaking expert Knox, and the other is Turing. If Poland's interpretation of Enigma laid the foundation for the deciphering of World War II passwords, then Turing, Knox and their team were the core forces of World War II to decipher the German code. In Germany, Enigma continued to change and improve the coding process. The Turing team continued to research, imitate and decipher the German cryptograph, and finally produced a cipher that could decipher German intelligence and named it "bomb." Since then, with the help of "bombs", most of the German actions in World War II have been continuously transmitted from the Turing team to the British military command center to help the British army win and reduce war losses. It can be said that the turn of World War II has a lot to do with the deciphering of the cipher machine, but as for why the cipher machine has been deciphered for a long time, but the war lasted for six years, which is related to the policies and military strategies of the Allies at the time. It's a big deal, after all, cryptography is just a boost.

● Modern cryptography

Modern cryptography is based on cryptography to establish a theoretical basis and become a science to judge. In 1949, Shannon published a paper entitled "Information Theory of Confidential Systems", introducing information theory, proposing two major design principles of confusion and diffusion, and laid the theoretical foundation for the relative system of cryptography. Shannon's cryptography theory favors symmetric cryptography and is divided into block ciphers and stream ciphers. Packet encryption is to divide the plaintext into modules of equal length, each group is encrypted separately using a certain algorithm and a symmetric key, and is applied to software class encryption, such as email encryption and bank transaction transfer encryption; and the stream password is encrypted and Both sides of the decryption use the same pseudo-random encrypted data stream as the key, usually a cryptographic operation on one bit, which is usually used for hardware encryption because the actual operation is relatively more difficult.

Although in 1949, cryptography began to have a certain theoretical prototype, but due to the limitations of historical and realistic conditions, it is mainly used by government agencies and military command posts. And cryptography really began to enter the development period or from the mid-1970s. In 1976, American cryptographers Diffie and Herman published a new book called "The New Direction of Cryptography", which opened a new chapter in the public key cryptosystem and is contemporary. It mainly adopts the operation of encrypting and decrypting two related keys separately. The encryption key is public, called “public key”. Not only can the algorithm be disclosed, but the key can also be disclosed, and the decryption key is exclusive to the user. For the "private key", the two keys are related and different. Based on a special one-way trapdoor function, it is no longer a simple form substitution and replacement, which increases the level of confidentiality. In 1977, the United States officially promulgated the data encryption standard DES for non-state security agencies, forming the initial specification of the cryptography industry, and pushing cryptography to a wider range of applications. The most classic public key encryption algorithm is the RSA algorithm constructed by the number theory method of Rivest, Shamir and Adelman from the United States in 1978. It is more asymmetric asymmetric encryption. A high encryption algorithm is by far the most mature public key cryptosystem.

Speaking of this, we can see that cryptography has finally begun to show a certain correlation with the blockchain encryption technology. Because the most commonly used encryption technology in the blockchain is the asymmetric encryption technology that utilizes RSA, the receiving address of each user is the public key, and the private key is also used for signature, and the information is asymmetrically encrypted to ensure its protection. safety.

With the development of time and people's pursuit of privacy and freedom, geeks composed of geeks began to explore anonymous communication, anonymous transactions, blind signature technology and digital assets, pursuing privacy exposure based on personal wishes. As a result, David Cham, a digital asset pioneer who created anonymous digital cash eCash and blind signature technology, and bitcoin, time stamps, distributed storage, etc., which are widely used in the blockchain industry, are known to us. technology. Of course, here are some of the technologies that are currently used in the main application of anonymous currency. We will elaborate on the main technical principles and the comparison of mainstream anonymous coins.

Third, technology application: the main data comparison of anonymous coins

1. Existing anonymous coins

2. Analysis of current mainstream anonymous currency

1) Comparison of technical advantages and disadvantages

2) Comparison of key data

Reference materials:

[1]. Wikipedia: Cryptography

[2]. Qin Yiji, "The History of Cryptography and the Technical Milestones of People in the Past 40 Years"

[3]. Sun Xue, "The History of the Development of Cryptography"

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