In this blog post, we will learn how public key encryption works and how secure it really is for protecting your information.

Public key encryption: The key to secure shopping

When shopping online, many people worry that someone might read the information sent between their computer and the online store’s computer and steal their credit card information.
However, with public key encryption, only the parties involved in the exchange can view the information. In public key encryption, each computer prepares a pair of keys that are unique and cannot be duplicated by any other computer. Let’s call the keys prepared by my computer the public key A and the private key a.
The public key A is shared with other computers, while the private key a is kept only on my computer. Information encrypted with public key A can only be decrypted and restored to its original form using the private key a. Even if someone obtains public key A, they cannot decrypt the information. Therefore, as long as the private key a remains on my computer, it is safe to share public key A with other computers.

How public key encryption works

Now, let’s consider the case of purchasing a book from an online bookstore called ‘Book Village.’ Suppose that the Book Village computer has a public key B and a private key b. When my computer connects to the Book Village computer, the two computers automatically exchange their public keys. In other words, my computer learns B, and the Book Village computer learns A. Now, when I enter my credit card information on my computer to place an order, my computer encrypts this information using Book Village’s public key B and sends it. Book Village’s computer decrypts the encrypted information using its private key b to obtain the original credit card information. Since the information encrypted with public key B can only be decrypted by Book Village’s computer, which possesses private key b, it is impossible for others to decrypt my credit card information.
Since my computer’s public key A is known to other computers, if someone else pretends to be me and shares their public key A from their computer to order a book, a problematic situation could arise. To prevent this, the Book Village computer must verify that the sender of the information it receives is indeed my computer. To do this, the Book Village computer sends an arbitrary word such as “Long live Book Village” to my computer, encrypts this word using my computer’s secret key a, and requests that the original word and the encrypted word be sent together. In public-key encryption, information encrypted with the secret key a can only be decrypted using the public key A. Therefore, my computer sends the original word and the encrypted word together. The Book Village computer, upon receiving these two pieces of information, decrypts the encrypted word using the public key A and checks if it matches the original word received. If they match, it is certain that the information was sent by the computer with the public key A (my computer).

Security of public-key encryption

Some people may worry that if someone figures out the secret key a from the public key A that their computer provided, they could access the encrypted information. However, from a technical standpoint, this is virtually impossible. The public key A can be derived from the secret key a through a simple calculation.
However, to derive the private key a from the public key A, even the fastest supercomputers available today would require decades of computation. The reason such an enormous amount of time and resources is required is that the mathematical foundation of public-key encryption is extremely robust. This method is based on mathematical problems such as integer factorization, which are designed to take an extremely long time to solve.
Additionally, public-key encryption continues to improve in security as computers evolve. By using new algorithms and longer key lengths, the strength of encryption can be enhanced, ensuring more secure communication. As a result, public-key encryption remains a reliable and trusted security technology.

Applications of public key encryption

Public key encryption is used in various fields, including online shopping, email security, database access control, and digital signatures. In email security, public key encryption is used to ensure that the contents of an email are not exposed to anyone other than the sender and recipient.
In database access control, public-key cryptography is used to verify that users accessing the database are authorized and to maintain data integrity. In digital signatures, public-key cryptography is used to verify the identity of the document’s creator and to prove that the document has not been altered since it was created.
With this technology, we can build a more secure Internet environment and effectively maintain personal information protection and data security.
In conclusion, public key encryption plays a very important role in online transactions such as Internet shopping malls. With this technology, we can securely protect credit card information and use the Internet with peace of mind. In the future, public key encryption will continue to evolve and be applied in more ways to make our digital lives even safer.