Asymmetric Key Encryption

Hello friends! Today we are going to look at asymmetric key encryption. So far we were talking about many security topics. If you are newbie for cryptography please go through our introduction to cryptography concepts post. You can learn the basics of encryption.

What is symmetric key encryption

What is asymmetric key encryption?

asymmetric encryption is also known as the public key encryption. The meaning of asymmetric means two things, not same. In asymmetric key encryption we use two keys for the encryption. They are public key and private key. Everyone who are doing the communication through a media will have both private and public keys. Public key is not a secret. Private key is a secret key. It is only known by the it owns party only.

How asymmetric key encryption works?

Now we know some brief information related to asymmetric key encryption like what is asymmetric key encryption. Let’s now look at the mechanism of the asymmetric key encryption. How asymmetric key encryption works?. Since two keys use in asymmetric key encryption both keys have to use for encryption. So if a message encrypt by private key it should decrypt from using public key. If not if a message encrypt by public key it has to decrypt by private key. Now we know we have to use both keys but the question is what is the order? What keys will use for encryption and decryption? So far I hope you aware about that sender does the encryption and receiver does the decryption. In the beginning I told you private key is a secret one. Let’s look at the possible encryption and decryption patterns and let’s see what is the pattern we use for asymmetric key encryption.

If we do the encryption using sender’s public key it can decrypt only by sender’s private key. Sender’s private key only knows by sender so there is no chance receiver can decrypt it. If we are going to share the private key to receiver it won’t be secure anyway. What you have to keep remember is if we use one’s public or private key to encryption that one’s private or public key has to use for decryption as well. We can’t use sender’s public key for encryption and receiver’s private key for decryption. The key pairs has to be same person either sender or receiver.

Mechanism behind asymmetric key encryption

So in asymmetric key encryption we use receiver’s pubic key for encryption. because everyone in the communication channel knows the public key of every node. It is not a secret. When the message encrypt by one’s public key it can decrypt only by that one’s private key which only knows by them. So receiver will decrypt the message with it’s private key. In asymmetric key encryption we use receiver’s public key to encrypt the message and decrypt it by receiver’s private key.

Formula of asymmetric key encryption

Encrypt(Receiver public key, Message) | Decrypt (Receiver private key, Cipher Text)

Algorithms for asymmetric key encryption

There are so many public key algorithms we use. They are RSA, DSA. Apart from that we have Diffie Helman and ecliptic curve algorithms. We use them for key exchange. DSA algorithm is not using to encryption only RSA is using. Digital signatures ensures the integrity and non-repudiation. Yet it is also a application where public key encryption uses. Diffie Helman use to the key exchange. They are also not using as a encryption algorithms. We are writing separate posts for those algorithms also therefore read those articles as well.


Hope you have understand what is asymmetric key encryption. If you like this post please share and comment. We are writing more contents regarding this topics. Keep reading us. Thank you. We will meet soon with another post soon.

Audy Ranathunga

Audy Ranathunga, Author of myexamnote is our most experienced author. She has been working as a blog post writer for 4 years. She joined with myexamnote before 1 year ago and she has contribute lots of valuable posts for readers.

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