What is public key cryptography?

Public key cryptography (PKC), also known as asymmetric cryptography, is a mechanism that uses both public and private keys, corresponding to symmetric cryptography that uses a single key. . The use of key pairs gives PKC unique functions and properties to solve the inherent challenges present in other cryptography technologies. This form of cryptography has become an important principle in modern computer security and is a key component of the growing cryptocurrency ecosystem.

How public key cryptography works

In the PKC system, the sender The public key is used to encrypt the message, and the recipient uses the private key to decrypt the message. Since the two keys are completely different, the public key can be shared safely without worrying about compromising the security of the private key. Each set of asymmetric key pairs is unique, thus ensuring that information encrypted using the public key can only be read by the person holding the corresponding private key.

And, because the key pairs generated by asymmetric encryption algorithms are mathematically related, their key lengths are longer than those used in symmetric cryptography. many. Its length is usually 1024 or 2048 bits, so it becomes extremely difficult to use the public key to calculate the corresponding private key. Today, the most common asymmetric encryption algorithm is called RSA. In the RSA scheme, the key is generated by multiplying two numbers (usually two larger prime numbers) and taking the common modulus. The modulus will generate two keys, one is a public key that can be shared, and the other is a private key that needs to be kept secret. The RSA algorithm was first proposed by Rivest, Shamir and Adleman (so called RSA) in 1977, and it is still an important part of the public key cryptography system.

Use PKC as an encryption tool

Public key cryptography solves the symmetric algorithm A mid- to long-term problem is the communication problem between encryption keys and decryption keys. Sending a symmetric key over an unsecured connection risks exposing it to a third party, who can then read any information encrypted by the shared key. While cryptography techniques such as the Diffie-Hellman key exchange protocol exist to solve this problem, these keys are still vulnerable. In public-key cryptography, you don't have to worry about this problem at all, and the keys used for encryption can be shared across any network connection. At this point, the asymmetric algorithm provides a higher level of protection than the symmetric algorithm.

Use cases in digital signatures

Another application of asymmetric cryptography algorithms That is to use digital signatures to verify data. Essentially, a digital signature is a hash created using the data in the message. After a message is sent, the recipient can verify the signature using the sender's public key to verify the message's origin and ensure that the message has not been tampered with. In some cases, digital signatures and encryption techniques are applied simultaneously because the hash itself may be encrypted. However, it should be noted that not all digital signature systems use encryption technology.

Limitations

Indeed, PKC can be used to improve computer security And verify the integrity of the information, but it also has certain limitations. Since encryption and decryption involve complex mathematical operations, asymmetric algorithms can also be slightly slow when processing large amounts of data. And this type of cryptography also relies heavily on the assumption of private key confidentiality. If a private key is accidentally shared or disclosed, the security of information encrypted using its corresponding public key will be compromised. Sometimes a user's private key may also be accidentally lost, in which case the user will lose access to the encrypted data.

Application of public key cryptography

This type of password It is used by many modern computer systems to provide security for sensitive information. For example, public key cryptography can be used to encrypt emails to ensure the confidentiality of their contents. The Secure Sockets Layer (SSL) protocol that allows secure connections to websites also uses asymmetric cryptography. PKC systems are also being used to explore secure electronic voting environments that would allow voters to participate in elections on their home computers.

PKC’s characteristics are also outstanding in blockchain and cryptocurrency technology. When a new cryptocurrency wallet is created, a pair of keys (public and private) are generated. Public addresses are generated using the public key and can be shared securely with others. Private keys, on the other hand, are used to create digital signatures and verify transactions, so they must be kept secret. When a transaction is verified by the certified hash in the digital signature, it can be added to the blockchain ledger. This digital signature system ensures that only users with the corresponding private key to the cryptocurrency wallet can access funds from the wallet. But it's worth noting that asymmetric ciphers used in cryptocurrency applications are different from those used for computer security purposes. For example, Bitcoin and Ethereum use the Elliptic Curve Digital Signature Algorithm (ECDSA) to verify transactions.

From computer security to verifying cryptocurrency transactions, public key cryptography plays a key role in securing modern digital systems. By using pairs of public and private keys, asymmetric cryptography algorithms solve the security problems inherent in symmetric cryptography. The use of PKC has been experienced for many years, and its applications in emerging fields are constantly being developed, especially in the field of blockchain and cryptocurrency.