Symmetric key encryption (or symmetric encryption) refers to a cryptographic scheme that uses the same key for encryption and decryption. Over the past few decades, this method of encrypting information has been widely used in government and military secret communications. Nowadays, symmetric key algorithms are also widely used in various types of computer systems to enhance data security.

How does symmetric encryption work?

Symmetric encryption schemes rely on the same key being shared between two or more users. The same key is used to encrypt and decrypt the so-called plaintext, which represents the message or data segment being encoded. The encryption process can be roughly summarized as follows: plaintext (as input) is encrypted using an encryption algorithm, which then generates ciphertext (output) from the plaintext.

If the encryption scheme is strong enough, the only way for people to read or access the ciphertext information is to decrypt it using the corresponding encryption key. The decryption process basically converts the ciphertext back into plaintext.

The security of symmetric encryption systems is based on the difficulty of randomly guessing the corresponding keys to break them. For example, it would take at least billions of years to crack a 128-bit key using ordinary computer hardware. The longer the encryption key, the harder it is to crack it. The 256-bit key is generally considered extremely secure and theoretically resistant to brute force attacks by quantum computers.

The two most common symmetric encryption schemes in use today are based on block ciphers and stream ciphers. Block ciphers group data into blocks of predetermined size and encrypt each block using a corresponding key and encryption algorithm (for example, 128-bit plaintext is encrypted into 128-bit ciphertext). On the other hand, stream ciphers do not encrypt plaintext data in blocks, but in stream increments of 1 bit (that is, 1 bit of plaintext is encrypted into 1 bit of ciphertext at a time).

Symmetric and asymmetric encryption

Symmetric encryption is the two methods of encrypting data in modern computer systems. One of the main methods. The other is what is called asymmetric encryption, sometimes also called public key encryption. The main difference between the above two methods is that asymmetric encryption systems use two different keys for encryption and decryption, unlike the same key used in symmetric encryption. In asymmetric encryption, one of the keys is shared (the public key), while the other key must be kept secret (the private key).

The use of two different keys by the asymmetric encryption algorithm is also the reason why it has functional differences from the symmetric key. Asymmetric algorithms are more complex and slower than symmetric algorithms. Because the public and private keys used in asymmetric encryption are arithmetically related to some extent, the keys themselves must be long enough to achieve the same level of security as symmetric encryption algorithms (which use shorter encryption keys) .

Applications in modern computer systems

Symmetric encryption algorithms are used in many modern computer systems to enhance data security sex and user privacy. Advanced Encryption Standard (AES), widely used in secure messaging applications and cloud storage, is a common use case for symmetric ciphers.

In addition to software implementation, AES can also be implemented directly in computer hardware. Hardware-based symmetric encryption schemes typically utilize AES 256, a specific variant of the Advanced Encryption Standard with a key length of 256 bits.

It is worth noting that Bitcoin’s blockchain does not use encryption as most people think. Instead, it uses a special digital signature algorithm (DSA) called the Elliptic Curve Digital Signature Algorithm (ECDSA), which generates digital signatures without the use of encryption algorithms.

A common point of confusion is that ECDSA is based on elliptic curve cryptography (ECC), which can also be applied to a variety of different tasks, including encryption, digital signatures, and pseudo-random generators. However, ECDSA itself cannot be used for encryption at all.

Analysis of advantages and disadvantages

Symmetric encryption algorithm can provide relatively high Security level, supporting both fast encryption and decryption of messages. The relative ease of symmetric cryptographic systems is also a logical advantage, since they consume fewer computing resources than asymmetric systems. Additionally, the security provided by symmetric encryption can be achieved by increasing the key length. As the length of the symmetric key increases, the difficulty of a brute force attack to break the encryption increases exponentially.

While symmetric encryption offers many advantages, it also has a serious drawback: the keys used to encrypt and decrypt data are the same. When these keys are shared across unsecured network connections, they can easily be intercepted by malicious third parties. If an unauthorized user gains access to a specific key, the security of data encrypted using that key is compromised. To solve this problem, many web protocols use a combination of symmetric and asymmetric encryption to establish secure connections. The most common example of such a hybrid protocol is Transport Layer Security (TLS), which is used to secure most network connections on the modern Internet.

It should also be noted that all types of computer encryption can be affected by vulnerabilities due to improper implementation. Although a long enough key mathematically renders a brute force attack ineffective, programmers' misconfigurations often create vulnerabilities, opening up new avenues for network attackers.

Summary ideas

Due to the relatively fast operation speed of symmetric encryption, it is easy to use and safe. Highly reliable, symmetric encryption is widely used in various applications such as Internet traffic protection and data protection on cloud servers. In order to solve the security problem of transmitting keys, it is often used in conjunction with asymmetric encryption, but symmetric encryption schemes remain a key component of modern computer security.