Crypto Stories: A Brief History From Symmetric Encryption To Bitcoin

Without public key cryptography, cryptocurrencies would fail.image description

16th century French cipher machine

People use the art and science of cryptography to encode (i.e. encrypt) information so that no one other than the intended audience can read it. Only the correct recipient can decode (i.e. decrypt) the message, which preserves privacy between communicators.

key forEncrypt and decrypt information. In asymmetric cryptography (another term for public-key cryptography), the key used to encrypt information is different from the key used to decrypt it.

Whereas in symmetric cryptography, the key used to decrypt the message is the same key used to encrypt it. This creates the problem of key exchange:The sender not only needs to send the message, but also find a secure way to send the key.If a bad guy intercepts both the key and the information, privacy will be violated.

Linguistics, language, and puzzle techniques have long dominated the history of cryptography.But from the mid-20th century onwards, mathematics dominated.

In the 1970s, Whitfield Diffie, Martin Hellman, and Ralph Merkle at Stanford University discovered a mathematical solution to the key exchange problem. In their solution, they used a modular algorithm and one-way functions. (Ralph Merkle is the inventor of the Merkle tree and has made great contributions to cryptocurrencies.)

Modular algorithms work with remainders and combine a set of numbers that, after reaching a certain point, begin to cycle. That is, 7 modulo 3 equals 1 because the remainder after dividing 7 by 3 is 1. The most common example of a modular algorithm loop is a 12-hour clock. If it is 8:00 in the morning, 6 hours later it will not be 14:00, but 2:00 in the afternoon. The point is that modular algorithms behave unintuitively and produce unexpected results.

In the field of mathematics,One-way functions are easy to implement, but also strongly resist reverse engineering.Take, for example, a bowl of soup in a restaurant. A chef can easily follow a recipe or improvise with ingredients on hand. You may be able to find that flavor and these spices, but without the recipe and the exact ingredients the chef used, its going to be hard to replicate that soup.

According to the Whitfield-Diffie algorithm,Correspondents share some public information about the key, but keep private information, preventing eavesdroppers from copying the key.The team presented their solution publicly at the National Computer Conference (USA) in June 1976.

Whitfield-Diffie solves the key exchange problem, but still uses symmetric encryption.

After learning about the Whitfield-Diffie solution, Ron Rivest, Adi Shamir, and Leonard Adelman at MITs Computer Science Laboratory began looking for a solution to asymmetric encryption based on these mathematical concepts. In April 1977, they succeeded in finding the RSA algorithm.

When using asymmetric encryption, you publish a public key.People can use the public key to encrypt information, but only you can decrypt it because you have the private key.In short, a public key is simply the number produced by multiplying two private keys together. If the numbers used are large enough, it would take a lot of computation and time for someone else to find those two numbers.

1923 patent application for an electric cipher machine

At the time, using RSA encryption was challenging with computer resources. Encryption belongs only to the powerful and wealthy - militaries, governments, large corporations, etc. Paul Zimmerman conceived,Anyone can encrypt by using a personal computer.In June 1991, he created Pretty Good Privacy (PGP) and released it to the public for free.

By using a hybrid algorithm, Zimmerman solved the problem that asymmetric encryption technology consumes a lot of resources and is slow to calculate. People use a symmetric key to encrypt the message itself, and then use asymmetric encryption to process the key and send it securely along with the message.

Secret Content Decoder Ring

The first employee Phil Zimmerman hired for PGP was Hal Finney.When an unknown man calling himself Satoshi Nakamoto showed up in 2008 and proposed so-called bitcoin, Hal Finney was the first to express interest.

In the 1990s, many attempts to create private electronic money using asymmetric encryption were unsuccessful.

David Chaum created DigiCash, but required all transactions to be verified by a centralized company. In 1998, Chaums company went bankrupt, and DigiCash went bankrupt with it.

In 1997, British researcher Adam Back created HashCash using the proof of work mechanism (Proof of Work). HashCash also failed in the end, because a coin can only be used once. Every time a user needs to buy something, they needmake new coins。

Hal Finney created the first Reusable Proof of Work (RPOW) system,Can solve the problem of HashCash. He tried to run the digital currency project with the so-called CRASH (short for Crypto cASH). (Lesson learned: If you name a computer program after CRASH, expect it to crash.)

Hal Finney was the first person since Satoshi Nakamoto to run a Bitcoin node and was the recipient of the first Bitcoin transaction on the network.

Hal Finney once encouraged Satoshi Nakamoto: Imagine that Bitcoin is successful and will become the payment system used globally. Then the total value of currency should be equal to the total value of all the wealth in the world... Even if Bitcoin is difficult With that level of success, are they really worth 100 million to one? Thats really something to think about.

Later, Hal Finney suffered from the fatal disease amyotrophic lateral sclerosis (ALS). He posted to the community on March 19, 2013farewell letterMentioned in:

A few days later, Bitcoin was running very stable, so I let it run by itself. At that time, the difficulty was only 1, and you could mine blocks with a CPU, and you didnt even need a GPU. I will spend the next few days Mined some blocks. But since it made my computer very hot and the fan noise was bothering, I turned it off... then heard about bitcoin in late 2010,I was amazed to learn that Bitcoin is not only still developing, but actually has monetary value.I opened my previous wallet and was relieved to find that the bitcoins were still there. As the price of bitcoin climbed, I transferred bitcoins to offline wallets, hoping they would hold some value to my heirs.

From Whitfield-Diffie to Bitcoin, the history of cryptography continues to progress.Math provides the foundation.Modern mathematics unlocks possibilities unheard of in the mid-20th century. Mathematical research continues, and when quantum computing becomes common, new mathematical possibilities will emerge.

Beyond mathematics, decentralization drives the development of modern cryptography.read more

In fact, many sources provide in-depth information on the history of cryptography and the emergence of cryptocurrencies:

A popular book on the history of cryptography is Simon Singhs Codebook: The Science of Secrecy from Ancient Egypt to Quantum Cryptography (The Code Book:The Science of Secrecy from Ancient Egypt to Quantum Cryptography）。

Nathaniel Popper in Digital Gold: The Inside Story of Bitcoin and the Marginals and Millionaires Trying to Reshape the Monetary System (Digital Gold:Bitcoin and the Inside Story of the Misfits and Millionaires Trying to Reinvent Money) covered the early history of cryptocurrencies.

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