Apakah itu Cryptography Kunci Simetris (Symmetric Key Cryptography)?

Symmetric Key Cryptography or symmetric encryption is a type of encryption scheme that uses the same key to encrypt and decrypt messages. This method of encoding information has been widely used in recent decades to facilitate secret communications between governments and the military. Today, symmetric key algorithms are widely used in many types of computerized systems to improve data security.

How does symmetric encryption work?

Symmetric encryption schemes rely on a key being shared among two or more users. The same key is used to encrypt and decrypt what is called plaintext (which represents the message or encoded piece of data). The encryption process involves running the plaintext (input) through an encryption algorithm called a cipher, which will produce a ciphertext (output).

If the encryption scheme is strong enough, the only way for someone to read or access the information contained in the ciphertext is to use the key to decrypt it. This decryption process usually converts the ciphertext back into plaintext.

The security of a symmetric encryption system is based on how difficult it is to randomly guess the key pair if you want to open it by force. For example, a 128-bit key would take a general computer billions of years to guess. The longer the encryption key, the more difficult it is to unlock. Keys with a length of 256-bits are generally considered to be highly secure and theoretically resistant to quantum computer brute force attacks.

Two symmetric encryption schemes commonly used today are block and stream ciphers. Block ciphers combine data into blocks of a predetermined size and each block is encrypted using a key pair and encryption algorithm (example: 128-bit plaintext is encrypted into 128-bit ciphertext). On the other hand, stream ciphers do not encrypt plaintext data into blocks, but in 1-bit increments (1-bit plaintext is encrypted into 1-bit ciphertext one by one).

Symmetric vs asymmetric encryption

Symmetric encryption is one of the two main methods of encrypting data in modern computer systems. Another asymmetric encryption, often referred to as public key cryptography. The main difference between these two methods is the fact that the asymmetric system uses two keys compared to what the symmetric scheme uses. One key can be shared publicly (public key), whereas the other key must be kept private (private key).

The use of two keys instead of just one provides a different functional variant between symmetric and asymmetric encryption. Asymmetric algorithms are more complex and slower than symmetric algorithms.

Its use in modern computerized systems

Symmetric encryption algorithms are used in many modern computing systems to increase data security and user privacy. Advanced Encryption Standard (AES) which is widely used in the security of messaging applications and cloud storage is a prime example of a symmetric cipher.

Moreover, apart from software implementation, AES can also be implemented directly on computer hardware. Hardware-based symmetric encryption schemes typically affect AES 256, which is a specific variant of the Advanced Encryption Standard that has a key size of 256 bits.

It's important to remember that the Bitcoin blockchain does not use encryption as many of its users believe. However, it uses a specific digital signature algorithm (DSA) known as the Elliptic Curve Digital Signature Algorithm (ECDSA) which generates digital signatures without using encryption.

A point of confusion in this regard is that ECDSA is based on an elliptic-curve cryptography (ECC), which in turn can be applied to several tasks, including encryption, digital signatures, and a pseudo-random generator. However, ECDSA itself is not used for encryption at all.

Advantages and disadvantages

Symmetric algorithms provide a fairly high level of security and at the same time allow a message to be encrypted and decrypted quickly. The simplicity of symmetric systems also provides convenience in terms of logistics, as they require less computing power compared to asymmetric ones. Moreover, the security provided by symmetric encryption can be scaled simply by increasing the key length. For each bit added to the length of the symmetric key, the difficulty of breaking the encryption with a brute force attack increases greatly.

Although asymmetric encryption offers many benefits, there is a major drawback associated with it: the way it transmits the keys used for data encryption and decryption. When such keys are shared over unsecured connections, they are highly vulnerable to interception by malicious third parties. If an unauthorized user gains access to a symmetric key, the security of data encrypted using that key will be compromised. To solve this problem, many website protocols use a combination of symmetric and asymmetric encryption to create a secure connection. The most important example of this hybrid system is the Transport Layer Security (TLS) cryptography protocol which is widely used on the modern internet.

It's also important to remember that any type of computer encryption can be vulnerable to attack if used improperly. Although a long enough key can make brute force attacks mathematically impossible, implementation errors made by programmers often make this weakness an entry point for cyber attacks.

Conclusion

Thanks to its speed, simplicity and security, symmetric encryption is widely used in applications ranging from monitoring internet traffic to securing data stored on cloud servers. While it is often used in pair with symmetric encryption to solve the problem of being able to transfer keys securely, symmetric encryption schemes remain an important component in modern computing security.