Encryption is the principal application of cryptography; it makes data incomprehensible in order to ensure its confidentiality. Encryption uses an algorithm called a cipher and a secret value called the key; if you don’t know the secret key, you can’t decrypt, nor can you learn any bit of information on the encrypted message—and neither can any attacker.

A cipher (or cypher) is an algorithm for performing encryption or decryption which is a series of well-defined steps that can be followed as a procedure. Modern ciphers are used by symmetric & asymmetric encryption, which are further classified depending on whether the same key or a key pair being used to encrypt or decrypt data.

### Symmetric Encryption

Symmetric encryption is a conventional method of Encryption and is the simplest of two techniques. Symmetric encryption is executed by means of only one secret key known as ‘Symmetric Key’ which is possessed by both sender and receiver. This key is applied to encode and decode the information. The sender uses this key before sending the message and the receiver uses it to decipher the encoded message.

This is a pretty straightforward technique and as a result, it doesn’t take much time. When it comes to transferring huge data, symmetrical keys are preferred.

### Asymmetric Encryption

Asymmetric Encryption, also known as Public Key Cryptography, requires users to create a matching key pair. In the key pair, one key is made public while keeping the other secret. The generation of key pair depends on the type of cryptographic algorithm used. The robustness of the asymmetric encryption depends on key management, number of bits used for generating the keys and public key infrastructure (PKI).

In asymmetric encryption, a message encrypted with the public key can be decrypted only with the corresponding private key pair. The public key and the private key are related mathematically, but it is computationally impractical to derive the private key from the public key. So, a recipient could distribute his/her public key widely. Anyone can use the public key to encrypt messages for the recipient and only the recipient can decrypt them with his/her own private key.

### Finally..

Symmetric encryption should be used when you want to send a quick encrypted message. Asymmetric encryption should be used when you have a verified public key infrastructure of your recipient. We should use a combination of asymmetric encryption with digital signatures to make our data more secure.

Further reading: Wikipedia, Tutorialspoint

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