Blockchain Public Lecture Series #2: The Core Technology of Bitcoin - Private Keys, Public Keys, Addresses, and Wallets in Depth."
Table of Contents
- Introduction:
- RELATED:
Introduction:
Hello, I am a student of the Blockchain Innovation Endowed Chair at the University of Tokyo. I am currently participating in a public course offered by the Blockchain Innovation Endowed Chair at the University of Tokyo. This course has been a very exciting experience for me as I have learned a wide range of topics from the basics to the latest trends in blockchain technology.
I have written this blog post to organize the contents of the second lecture for my own understanding and at the same time to share this knowledge with others. This article is the result of my learning and at the same time part of my review. I hope it will be of some help to those who are interested in blockchain technology.
Let me explain what I understand about the core technology of Bitcoin.
Basic Components of Bitcoin
2.1 Private Key: Signature of the Digital World
The private key is one of the most important elements in the Bitcoin system. It is a 256-bit number, randomly chosen from an astronomical number of about 10^77. To understand the magnitude of this number, consider that the total number of protons in the universe (Eddington number) is about 10^80.
A cryptographically secure pseudo-random number generator (CSPRNG) is used to generate the secret key. This is important because it reduces the predictability of the key to an absolute minimum.
2.2 Public key: public version of private key
The public key is generated from the private key, and the process uses advanced mathematics called elliptic curve cryptography. Specifically, it is represented as a point on a particular elliptic curve called secp256k1.
Interestingly, public keys come in two formats: "compressed" and "uncompressed. The compressed format is represented as 33 bytes of data, while the uncompressed format is 65 bytes. The use of the compressed format reduces transaction size, resulting in fee savings.
2.3 Bitcoin address: Transaction destination
The bitcoin address is generated by further processing the public key. Specifically, two hash functions, SHA256 and RIPEMD160, are applied and the result is encoded with Base58Check. This process produces a 26-35 character string beginning with 1.
Wallet: the key to key management
3.1 Non-Deterministic Wallet
Non-deterministic wallets randomly generate a new private key for each address. While this is intuitive, it is currently discouraged because it is difficult to back up.
3.2 Deterministic Wallet
Deterministic wallets generate many keys from a single seed. This approach allows all keys to be recovered as long as one seed is backed up.
3.3 HD Wallet: Innovative Key Management System
The HD (Hierarchical Deterministic) wallet is an evolution of the deterministic wallet. It is an innovative system that allows hierarchical key generation from a parent key to a child key to a grandchild key. Notably, the use of an "extended public key" makes it possible to generate a new public key without having a private key. This makes it possible to securely generate a new address for each transaction in an online store, for example.
Cryptographic Applications: Elliptic Curve Cryptography and Hash Functions
The elliptic curve cryptography and hash functions used in Bitcoin represent the best of modern cryptography theory. Elliptic curve cryptography has the advantage over traditional RSA cryptography of providing equivalent security with a shorter key length and greater computational efficiency.
Hash functions, on the other hand, are used in various aspects of the bitcoin system, including data integrity verification and address generation. The right combination of these cryptographic techniques underpins the security and efficiency of bitcoin.
Security and Privacy Considerations
Bitcoin security relies primarily on cryptography, but the responsibility of the user is also important. In particular, control of the private key is critical, as its loss or theft can lead to the complete loss of the asset.
On the other hand, from a privacy perspective, bitcoin transactions are public and therefore not completely anonymous. However, some privacy protection is possible by changing addresses frequently.
Conclusion: The Future and Potential of Bitcoin
Understanding the basic technology of Bitcoin is important not only for understanding digital currency, but also for the future of digital society. The basic elements - private key, public key, address, and wallet - symbolize the sovereignty and responsibility of individuals in the digital world.
In the future, these technologies will continue to evolve and more user-friendly and safer systems will be developed. At the same time, the impact of these technologies on society must be continuously discussed and examined.
The Blockchain Public Lecture provides an opportunity for everyone to learn about this cutting-edge technology and its social impact. Through the democratization of technology and the sharing of knowledge, it is hoped that more people will be able to play a part in the digital revolution.
Bitcoin Basics
- Bitcoin.org
Official Bitcoin website. Provides a basic overview, how to choose a bitcoin wallet, and a guide to security. - Bitcoin Japanese Wiki
A bitcoin wiki written in Japanese, covering how bitcoin works, technical details, and explanations of related terms.
English 
日本語