Important points to remember about asymmetric encryption

Following are some of the most important points related to asymmetric encryption for passing exams and for general understanding.

• Asymmetric Encryption uses two mathematically related but different keys known as a key pair.

• The key pair within an asymmetric encryption is commonly referred to as a private key and a public key. 

• In Asymmetric encryption, we can encrypt with one of the keys in the key pair and then decrypt with the other key in the key pair.

• Some of the popular algorithms used in asymmetric encryption includes RSA, Diffie-Hellman, Elliptic Curve Cryptosystem (ECC) and El Gamal.

• Asymmetric encryption takes more time to process than symmetric encryption as it is more computationally intensive than symmetric encryption.

• Asymmetric encryption works on small block sizes as compared to larger block sizes with symmetric encryption.

• Symmetric encryption is less scalable compared to asymmetric encryption due to the single shared key with symmetric encryption.

• While symmetric encryption is used for encrypting large blocks of data, asymmetric encryption is used to encrypt digital signatures and keys during key exchanges.

• Asymmetric encryption can be explained with the use case of two parties A and B where A want to send a message that only B can read, which is usually referred to as confidentiality. A will encrypt data using an asymmetric cypher (e.g. RSA) and B's public key. B will then decrypt that message with same asymmetric cypher and B's private key. 

• Since asymmetric encryption is computationally intensive, in most practical cases a hybrid approach of symmetric and asymmetric encryption is used. Consider the same use case of two parties A and B where A want to send a message that only B can read. A will encrypt the message using a symmetric cypher and a session key. The session key alone is then encrypted using an asymmetric cypher (e.g. RSA) and B's public key. Both the encrypted message and key is passed to B. B first uses the same asymmetric cypher and B's private key to decrypt the session key and then use that session key to decrypt the actual message.