# Demystifying Symmetric and Asymmetric Methods of Encryption

We use unsecured media such as the Internet to communicate on a daily basis. While at it, how many of us pause to take into consideration the confidentiality of the information that we are sharing with each other? The most commonly applied method for securing information during the communication process is known as encryption, which is a major concept of cryptography. Encryption can simply be defined as the process through which a sender of information encodes a message to a format that is difficult for an eavesdropper to decipher.

Encryption is actually an age-old practice dating back to the times of the famous Roman king Caesar, who encrypted his messages using a Caesar cipher. The practice can be viewed as a transformation of information whereby the sender uses plain text, which is then encoded into cipher text to ensure that no eavesdropper interferes with the original plain text. On receiving the encoded message, the intended receiver decrypts it to obtain the original plain text message.

There are two main types of encryption:

- Symmetric
- Asymmetric

The glaring difference between the two main types of encryption is that while **Symmetric Encryption** also called as Secret Key Cryptography, it employs the same secret key for both encryption and decryption, that is used to exchange information during a secure session between client’s browser and web server with an **SSL Certificate** installed.

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**Asymmetric Encryption** also called as Public Key Cryptography and it uses two different keys – a public key used for encryption and a private key used for decryption, that is used in SSL handshake process. Unbeknownst to many, encryption is applied to some extent in almost all communication networks. Though it used to be limited to government communications and military installations, the advent of the widely used Internet made the urgency of securing information channels a priority, hence making encryption the mainstream solution.

## The Main Differences between Symmetric and Asymmetric Encryption

We can compare the two types of encryption using the following four major points:

**The Basics** – While Symmetric encryption makes use of a single key for both encryption and decryption, Asymmetric encryption uses different keys for encryption and decryption. It applies a public key for encryption, while a private key is used for decryption.

**Algorithms** – Symmetric encryption using algorithms like 3DES, DES, RC4, AES and QUAD. Whereas, Asymmetric encryption uses **RSA and ECC algorithms** to create the public and private keys.

**Performance** – While Symmetric encryption is fast in its execution, Asymmetric encryption tends to be slower in execution as a result of more complex algorithms which come with a high computation burden.

**Purpose** – Symmetric encryption is utilized for bulk data transmission. Whereas, Asymmetric encryption is mostly used for securely exchanging secret keys.

### Symmetric Encryption

This is a type of encryption whose technique allows the application of only one key for both encryption and decryption of a message that is being shared through a communication channel. Also known as the conventional encryption method, Symmetric encryption happens to be the oldest known method of encryption with the Caesar cipher falling in this category.

In this method, the plain text gets encrypted and then converted to the cipher text using an encryption algorithm and a key. On reaching the intended receiver, the ciphertext gets converted back to plain text utilizing the same key that was applied for encryption, and a decryption algorithm. The key used can be as easy as a secret number or just a string of letters.

We can use a shift cipher, which is a simple Symmetric Encryption technique, to demonstrate this. If your plain-text is, “COME TOMORROW” and your secret key is to shift each letter by three positions, then for instance letter “C” in the text becomes letter “F” in the cipher-text. This is precisely what is referred to as the Caesar cipher. Your plain text above will, therefore, look like “FRPH VRPRUURZ” after encryption. At first glance, the cipher message will be incomprehensible to any eavesdropper. However, once it is decoded using the secret key, it reverts to plain text once more.

Examples of modern Symmetric key encryption algorithms include block ciphers such as Blowfish, AES, DES, Camellia, and Serpent, or stream ciphers such as FISH, RC4, QUAD, Py, and SNOW.

### Asymmetric Encryption

This is an encryption technique that utilizes a pair of keys (a public key and a private key) for the encryption and decryption processes. The public key is normally used for encryption while the private key is applied for decryption of the message. Whereas the public key can be made freely available to any person who might be interested in sending a message, the private key remains a secret well kept by the receiver of the message. A message encrypted using a public key and an algorithm will be decrypted using the same algorithm plus a matching private key that corresponds to the public key used.

Asymmetric is also known as public key cryptography, Asymmetric encryption is a relatively new area when compared to the age-old symmetric encryption. The use of two keys in Asymmetric encryption came into the scene to fix an inherent weakness with the symmetric cipher. If an eavesdropper gets hold of the secret key in Symmetric encryption, then the whole point of encryption becomes useless. The probability of this happening is quite high since the secret key might have to be sent through unsecured channels of communication. Asymmetric encryption offers a security solution by applying two keys whereby one is public and the other one is Private key. Asymmetric key-pairs used in SSL Handshake (as a sort of verification method) – In this Handshake process, SSL/TLS connection is established between Server and Client’s browser before beginning of data transmission.

If a message is encrypted with a public key, then it can only be decrypted using a private key and vice versa. As a matter of fact, Asymmetric encryption is commonly used in our daily communication channels, particularly over the internet. Some of the modern Asymmetric key encryption algorithms include RSA, WELGamal, PGP, Elliptic curve techniques, SSH, and many others.

#### CONCLUSION

As a faster technique, Symmetric encryption is mostly used for bulk data transmission. On the other hand, the Asymmetric encryption being a complex and slower encryption technique comes in handy for exchanging keys. Therefore, the kind of encryption algorithm to be used in any given circumstance depends on the task at hand.

With the rampant cases of hacking communication systems, encryption experts must always ensure that they stay a step ahead of the hackers. For instance, the Asymmetric key cryptosystems’ security depends on a small set of number theory problems that are deemed difficult to decipher, though they were never mathematically proven as so. This means that any advances made in the number theory might one day make factoring a very easy problem hence compromising the security of the Asymmetric key cryptosystems.