The cryptography system is currently divided into two main research areas: symmetric cryptography and asymmetric cryptography. Symmetric cryptography is often synonymous with symmetric encryption, and asymmetric cryptography includes two main use cases: asymmetric encryption and digital signatures.

Thus, we can group these concepts as follows:

• Symmetric key cryptography 
  • Symmetric encryption
• Asymmetric cryptography (or public key encryption)
  • Asymmetric encryption (or public key encryption)
  • Digital signatures (may include also May not include encryption)

This article will focus on symmetric and asymmetric encryption algorithms.

Symmetric encryption vs asymmetric encryption

Encryption algorithms are usually divided into two categories, called Symmetric and asymmetric encryption. The fundamental difference between these two encryption algorithms is that symmetric encryption algorithms use a single key, while asymmetric encryption uses two different but related keys. This description of the difference, although very simple, clearly explains the differences in functionality and use between the two encryption technologies. .

Understanding encryption keys

In cryptography, an encryption algorithm generates a number of bits Character keys are used to encrypt and decrypt a piece of information. The way these keys are used also illustrates the difference between symmetric and asymmetric encryption.

While symmetric encryption algorithms use the same key to perform encryption and decryption, conversely, asymmetric encryption algorithms use one key to encrypt data and another key to decrypt it . In an asymmetric encryption system, the key used for encryption is called the public key and can be shared with others. On the other hand, the key used for decryption is a private key and should be remembered and kept secret.

For example, if Alice sends Bob a message encrypted using a symmetric algorithm, she needs to share the encryption key she used for encryption with Bob so that he can decrypt the message. This means that if a malicious actor intercepts the key, they can easily access the encrypted information.

However, if Alice uses an asymmetric encryption algorithm, she will use Bob's public key to encrypt the message, and Bob can use his private key to decrypt the message. Therefore, asymmetric encryption provides a higher level of security because even if someone intercepts their message and obtains Bob's public key, they cannot decrypt the message.

Key length

Another functional difference between symmetric and asymmetric encryption is the The length of the key is measured in bits and is directly related to the level of security provided by each encryption algorithm.

In symmetric encryption, the key is randomly selected and its length is usually set to 128 or 256 bits, depending on the desired level of security. However, in asymmetric encryption, the public and private keys are mathematically related, meaning there is an arithmetical connection between the two. An attacker could exploit this pattern to crack the ciphertext, so asymmetric keys require longer key lengths to provide the same level of security. The difference in key length is so significant that a 128-bit symmetric key and a 2,048-bit asymmetric key provide roughly the same level of security.

Comparison of advantages and disadvantages

One of these two different types of encryption algorithms time, with different advantages and disadvantages. Symmetric encryption algorithms operate quickly and require less computing resources, but their main disadvantage is the distribution of keys. Because the same key is used when encrypting and decrypting information, that key must be distributed to those who need to access the data, which creates a security risk (as mentioned earlier).

In contrast, asymmetric encryption uses the public key for encryption and the private key for decryption to solve the problem of key distribution. The trade-off, however, is that asymmetric encryption systems run very slowly compared to symmetric encryption and require more computing resources due to their very long key lengths.

Application cases

Symmetric encryption

Symmetric encryption is widely used in modern computer systems to protect information due to its faster computing speed. For example, the U.S. government uses the Advanced Encryption Standard (AES) to encrypt and classify security information. AES replaces the previous Data Encryption Standard (DES), which was developed in the 1970s and has been the standard for symmetric encryption.

Asymmetric encryption

Asymmetric encryption is usually used for a large number of users who need to encrypt and decrypt at the same time In systems with messages or data, especially when the computing speed and computing resources are sufficient. A common use case for this system is encrypted email, where the public key can be used to encrypt the message and the private key can be used to decrypt it.

Hybrid encryption system

In many applications, symmetric and asymmetric encryption are used together . Typical examples of such hybrid systems are the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) encryption protocols, which are used to provide secure communications within the Internet. The SSL protocol is now considered insecure and should be discontinued. In contrast, the TLS protocol is currently considered secure and is widely used by major web browsers.

Do cryptocurrencies use cryptography?

The encryption technology used in many cryptocurrencies provides a higher level of security to end users. For example, when a user sets a password for their crypto wallet, an encryption algorithm is used to cryptographically encrypt the files used to access the software.

However, since Bitcoin and other cryptocurrencies use public and private keys, there is a common misconception that blockchain systems use asymmetric cryptography algorithms. As mentioned before, asymmetric encryption and digital signatures are the two main use cases of asymmetric cryptography (public key encryption).

Therefore, not all digital signature systems use encryption technology, even if they use public and private keys. In fact, it is possible to just digitally sign a message without encrypting it. RSA is an example algorithm for signing encrypted messages, but the digital signature algorithm used by Bitcoin (called ECDSA) does not use encryption at all.

Summary ideas

In today's digital age, symmetric and asymmetric encryption are It plays an important role in protecting sensitive information and network communications. While both are useful, they each have their own pros and cons, making them suitable for different use cases. With the continuous development of cryptography, cryptography can be used to better resist various new and complex threats. Symmetric and asymmetric encryption are also closely related to computer security.