The Difference Between Symmetric and Asymmetric Encryption

The Difference Between Symmetric and Asymmetric Encryption

Symmetric encryption uses a single key for encryption and decryption, while asymmetric encryption uses different keys for each process. Asymmetric encryption is slower and requires more computing power, but it provides better security. Symmetric encryption is faster, but it is vulnerable to interception and requires key distribution. Both encryption techniques have their advantages and disadvantages and are used together in many applications to provide secure communication on the Internet.


The study of cryptographic systems is divided into two primary fields, symmetric cryptography, and asymmetric cryptography. Symmetric encryption is frequently used interchangeably with symmetric cryptography. In contrast, asymmetric cryptography consists of two primary use cases, namely asymmetric encryption and digital signatures.

These groups can be categorized as follows:

  • Symmetric key cryptography, which includes symmetric encryption.
  • Asymmetric cryptography, also known as public-key cryptography, encompasses the following:
    • Asymmetric encryption, or public-key encryption.
    • Digital signatures, which may or may not involve encryption.

Now, let us delve deeper into this topic.

Symmetric vs. Asymmetric Encryption

The two primary categories of encryption algorithms are symmetric encryption and asymmetric encryption. These methods differ fundamentally because symmetric encryption employs a single key, whereas asymmetric encryption utilizes two related but distinct keys. This seemingly minor difference results in functional dissimilarities between the two encryption techniques and how they are employed.

Encryption Keys

Encryption algorithms generate keys to encrypt and decrypt data, and the way those keys are used distinguishes symmetric and asymmetric encryption. Symmetric algorithms use the same key for encryption and decryption, while asymmetric algorithms use different keys for each process. In asymmetric systems, the public key is shared and used for encryption, and the private key is kept secret and used for decryption. In a symmetric encryption scenario, Alice would share the key with Bob to decrypt her message, making it vulnerable to interception. In an asymmetric encryption scenario, Alice would use Bob's public key to encrypt her message, providing an extra layer of security against interception.

Encryption Key Length

Symmetric and asymmetric encryption algorithms have a functional difference regarding key length. The length of keys is measured in bits and correlates with the level of security provided by the algorithm. Symmetric keys are randomly selected, with lengths set at either 128 or 256 bits, while asymmetric keys require a mathematical relationship between the public and private keys. Attackers can exploit this relationship, making it necessary to use much longer asymmetric keys to maintain an equivalent level of security. A 128-bit symmetric key and a 2,048-bit asymmetric key provide comparable security.

Pros and Cons

Encryption algorithms can be classified into two categories: symmetric and asymmetric. While symmetric encryption algorithms are faster and require less computational power, their main disadvantage is key distribution since the same key is used for both encryption and decryption, and it must be distributed to anyone who needs to access the data.

On the other hand, asymmetric encryption algorithms use public keys for encryption and private keys for decryption, which solves the problem of key distribution. However, the disadvantage of asymmetric encryption systems is their slowness and the need for much more computing power due to their vastly longer key lengths.

Use Cases

Modern computer systems widely use symmetric encryption for its speed, with the Advanced Encryption Standard (AES) being an example. AES replaced the Data Encryption Standard (DES), a previous symmetric encryption standard developed in the 1970s.

Asymmetric encryption is suitable for systems in which multiple users need to encrypt and decrypt data when speed and computing power are not primary concerns. Encrypted email is one such system, using a public key to encrypt a message and a private key to decrypt it.

Symmetric and asymmetric encryption are used together in many applications, such as the Security Sockets Layer (SSL) and Transport Layer Security (TLS) cryptographic protocols, which provide secure communication within the internet. The SSL protocols are no longer secure and should not be used, while the TLS protocols are widely used by all major web browsers and are considered safe.

Using Encryption in Crypto

Cryptocurrency wallets often utilize encryption techniques to provide a higher level of security to users, such as when a password is set up. However, there is a common misconception that blockchain systems rely solely on asymmetric encryption algorithms, which is not entirely true. While digital signatures and asymmetric cryptography can be related, not all systems utilize encryption, and a message can be digitally signed without encryption. For example, Bitcoin's digital signature algorithm, named ECDSA, does not use encryption at all, while RSA can be used for signing encrypted messages.


The relevance of symmetric and asymmetric encryption techniques cannot be overstated in the present-day world where the protection of sensitive information and communications is critical. The suitability of each of these techniques depends on their respective advantages and disadvantages, and how they are applied. As the science of cryptography continues to evolve to defend against the increasing level of sophistication of security threats, both symmetric and asymmetric encryption will remain pertinent to computer security.

Asymmetric Keys
Symmetric Keys
Cryptographic Keys