How asymmetric encryption differs from symmetric encryption

Anton P. | November 30, 2021

Asymmetric encryption is one of the techniques users rely on for safe data transmissions over the internet. This type of modern cryptography revolves around two keys, one for encrypting and the other, secret key, for decrypting. Powered by complex mathematical principles, asymmetric encryption is not what most users fully grasp. Despite that, we use it regularly as it reassures security of procedures like signing digital documents. Let’s discuss the meaning and use of asymmetric cryptography and compare it to its counterpart, symmetric encryption.

What is asymmetric encryption?

Asymmetric encryption, also known as public-key encryption, is one of the most influential in modern cryptography. Essentially, it depends on two asymmetric keys, frequently referred to as public-private key pairs. The process uses one key to encrypt data and the second one to decrypt it.

Thus, the primary purpose of any cryptographic system is to protect data and prevent unauthorized access or use. This goal is precisely what asymmetric encryption works to achieve.

What exactly is a key?

You might be confused as to the meaning of key in asymmetric encryption or cryptography in general. It refers to strings of letters or numbers kept in a file. The file can either encrypt or decrypt data when processed via cryptographic algorithms.

Asymmetric encryption operates with a pair of keys:

  • Public key. This string is publicly available, and its purpose is to encrypt data. It can pass through the internet without much protection. However, it is essential to check that no external forces tamper with it. As a response, entities verify public keys via certificates. The process chains certificates with public key signatures signed by trusted authorities.
  • Private key. This piece of information finishes up the pair of asymmetric keys. It must stay private, and it is the only way to decrypt a message encrypted with the public key.

Rundown on how asymmetric encryption works

This cryptographic procedure follows clear-cut steps to secure data transmissions:

  1. Asymmetric encryption generates public and private keys randomly using an algorithm. The produced strings have mathematical relationships with each other.
  2. The key length can differ. For instance, the 2048-bit key size is the general recommendation for asymmetric encryption. The number of possible keys increases proportionally with the length. Thus, the longer the key, the more difficult it becomes to crack it.
  3. Say you start a data transmission online. The sender retrieves the receiver’s public key. As mentioned earlier, public keys are freely accessible to anyone.
  4. The sender uses the obtained public key to encrypt the message.
  5. The sender sends the encrypted message over the internet to the recipient.
  6. The receiver uses their private key to decrypt the message.

Where is asymmetric encryption used?

The impact of asymmetric encryption is tremendous as it safeguards many digital activities. It has a role in email security, web security, and many other encryption systems requiring key exchange over the public network. Here are several examples of where you might have encountered asymmetric cryptography:

  • Emails. Asymmetric encryption plays a role in encrypting and decrypting email messages. For instance, PGP (Pretty Good Privacy) uses both symmetric and public-key encryption.
  • Digital signatures. Public-key cryptography confirms the identity of someone signing a digital document.
  • Blockchain transactions. Asymmetric encryption validates actions taken using the private key with the related public key. In other words, blockchain uses it to authenticate transactions.
  • Internet infrastructure. SSL/TLS equips both asymmetric and symmetric encryption to safeguard the integrity and confidentiality of data in transit. Public-key cryptography aims to establish secure sessions between clients and servers.

Asymmetric encryption vs. symmetric encryption

Symmetric encryption is the opposite of asymmetric encryption. Here are some of the main factors revealing the differences between these two cryptographic techniques:

  • Symmetric cryptography relies on a single key, used both for encryption and decryption.
  • Asymmetric encryption is the newer cryptographic solution.
  • Systems frequently employ asymmetric encryption as a kind of handshake to create a secure channel to exchange symmetric keys.
  • Asymmetric cryptography is a more resource-demanding practice as the keys are typically longer. The use of two keys instead of one also contributes to the asymmetric process taking more time. Thus, symmetric encryption is much faster both in terms of encryption and decryption.
  • Asymmetric cryptography requires bigger key sizes to match the security of shorter keys in symmetric cryptography.
  • Usually, asymmetric encryption is the one labeled as more secure as it uses two keys for the process. However, it is slower and might not be suitable for performance-sensitive procedures.

Asymmetric encryption is, in theory, susceptible to brute force and man-in-the-middle attacks. For instance, the latter would mean that attackers intercept the exchange of keys and provide a different public key. However, both attacks are difficult, if not impossible, to implement due to the complexities of modern security mechanisms.

The biggest concern for symmetric encryption is the secure exchange of the key.

What cryptography does Atlas VPN use?

Both asymmetric and symmetric encryption can power Virtual Private Networks. However, Atlas VPN chooses ChaCha20Poly1305 and AES-256 to ensure the safest data transmissions online. These algorithms represent symmetric encryption, which works best with our goal to make each connection equally secure and fast.

Anton P.

Anton P.

Former chef and the head of Atlas VPN blog team. He's an experienced cybersecurity expert with a background of technical content writing.

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