In this blog post, we will find out how public key encryption works and how safe it actually keeps my information.
Public key encryption, the key to safe shopping
When buying something from an online store, many people worry that someone might read the information that goes back and forth between their computer and the online store’s computer and steal the credit card information they entered. However, using the public key encryption method, information can be made invisible to anyone other than the parties exchanging the information.
In the public key encryption method, each computer prepares a pair of keys that never overlap with those of other computers. Let’s say the key pair prepared by my computer is public key A and private key a. Public key A is used to inform other computers, and private key a is kept only on my computer. Information encrypted with public key A can only be decrypted with the secret key a to make it into the original information, and it cannot be decrypted even with public key A. Therefore, as long as the secret key a is not leaked from your computer, you can share public key A with other computers.
How public key encryption works
Now, let’s consider the case of purchasing a book by accessing the Internet bookstore “Book Village.” If the computer in Book Village has public key B and private key b, as soon as my computer connects to the computer in Book Village, the two computers automatically exchange their public keys. In other words, my computer learns B, and the computer in Book Village learns A. Now, when I enter my credit card information on my computer to order a book, my computer encrypts it with the public key B of the Book Village computer and sends it. The Book Village computer decrypts the encrypted information with its own private key b to obtain the original credit card information. Since only the Book Village computer with the private key b can decrypt the information sent with the public key B, it is impossible for anyone else to decrypt my credit card information.
Since public key A of my computer can be known by other computers, there can be a problem if someone pretends to be me and orders a book by telling the public key A from their computer. To prevent this problem, you must confirm that the sender of the information being received by the Book Village computer is your computer. To do this, the Book Village computer sends a random word such as “Book Village Manse” to my computer, encrypts this word with my computer’s secret key a, and then requests that the original word and the encrypted word be sent together. In the public key encryption method, information encrypted with the secret key a can only be decrypted with the public key A. Therefore, my computer sends the original word and the encrypted word together, and the book village computer that receives these two pieces of information decrypts the encrypted word with public key A and checks whether it matches the original word it received. If they match, it can be known that the information was sent by the computer (my computer) that has public key A.
Security of public key encryption
Some people may worry about what would happen if they were to find out the secret key a from the public key A that their computer taught them. However, such a thing is almost impossible from a technical standpoint. The public key A can be obtained from the secret key a with a simple calculation. However, to find the private key a from the public key A, it would take decades to calculate even with the fastest supercomputers. The reason for investing such time and resources is that the mathematical basis of public key cryptography is very strong. This method was created using mathematical problems such as factorization into prime numbers, and these problems are designed to take a very long time to solve.
In addition, the security level of public key cryptography continues to improve as computers evolve. By using new algorithms and longer key lengths, the strength of encryption can be increased and more secure communication can be guaranteed. As a result, public key cryptography continues to establish itself as a reliable security technology.
Applications of Public Key Cryptography
Public key cryptography is used in various fields, not just online shopping. For example, it is used for email security, database access control, and digital signatures. In email security, public key cryptography is used to ensure that the contents of the email are not exposed to anyone other than the sender and the recipient. In database access control, public key cryptography is used to verify that the user accessing the database is a legitimate user and to maintain the integrity of the data. Digital signatures use public key cryptography to verify who created a document and to prove that the document has not been altered since it was created.
Therefore, public key cryptography can generally be considered safe for people to use. This technology can help us build a safer Internet environment and effectively maintain privacy and data security.
In conclusion, public key cryptography plays a very important role in online transactions such as online shopping. This technology allows us to securely protect credit card information and use the Internet with confidence. Public key cryptography will continue to develop and be applied to make our digital lives more secure.
