Lesson 2: Understanding Public Key Cryptography

Public key cryptography, the mechanism for cryptocurrency

While common-key cryptography uses the same key for encryption and decryption, public-key cryptography uses a public key for encryption and a private key for decryption.

In this case, the public key used for encryption and the private key used for decryption must be paired.

Public key cryptography is suitable for situations where you want to grant access to data to a specific person.

For example, public key cryptography is most suitable to realize the basic mechanism of cryptocurrency, such as transferring cryptocurrency to a specific person and making it available only to that person.

Combination of common-key and public-key cryptography

Public key cryptography is slower than symmetric key cryptography because it uses different keys for encryption and decryption.

For this reason, public key cryptography is seldom used for large data transmissions.

In modern Internet communication, it is common to send not only images but also video files, and the opportunities to send large data are increasing rapidly.

In such modern times, public key cryptography is generally used to enhance the security of symmetric key cryptography.

Since symmetric key cryptography uses a common key for encryption and decryption, if the key is leaked, the data will be exposed.

In fact, most of the cryptographic techniques used in SSL/TLS (encrypted Internet communication) are based on a combination of symmetric key cryptography and public key cryptography.

Specifically, instead of using public key cryptography to encrypt and decrypt data, public key cryptography is often used to encrypt and decrypt the common key used to encrypt and decrypt data.