# What Is Asymmetric Encryption?

### Learn what asymmetric encryption is, how it works, and what it does.

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When it comes to the word encryption, we think of it as a technique that protects data using a cryptographic key, and there’s nothing wrong with this. However, what most people don’t realize is that there are certain types of encryption methods. Asymmetric encryption, also known as Public-Key cryptography, is an example of one type.

Unlike “normal” (symmetric) encryption, asymmetric encryption encrypts and decrypts the data using two separate yet mathematically-connected cryptographic keys. These keys are known as a ‘Public Key’ and a ‘Private Key.’ Together, they’re called a ‘Public and Private Key Pair.’

Let’s see how these two keys work together to create the formidable force that is asymmetric encryption.

## How Does Asymmetric Encryption Work?

Asymmetricencryption uses two distinct, yet related, keys. One key, the Public Key, is used for encryption, and the other, the Private Key, is for decryption. As implied in the name, the Private Key is intended to be private so that only the authenticated recipient can decrypt the message.

Let’s understand this with a simple example.

Pretend you’re a spy agency and you need to devise a mechanism for your agents to report in securely. You don’t need two-way communication; they have their orders; you just need regular, detailed reports coming in from them. Asymmetric encryption would allow you to create public keys for the agents to encrypt their information, with a private key back at headquarters that is the only way to decrypt it all. This provides an impenetrable form of one-way communication.

## How Are the Two Keys Generated?

At the heart of asymmetric encryption lies a cryptographic algorithm. This algorithm uses a key generation protocol (a kind of mathematical function) to generate a key pair. Both the keys are mathematically connected with each other. This relationship between the keys differs from one algorithm to another.

The algorithm is basically a combination of two functions – encryption function and decryption function. To state the obvious, the encryption function encrypts the data and decryption function decrypts it.

## Asymmetric Encryption in SSL/TLS Certificates

In SSL/TLS and other digital certificates, both methods – symmetric and asymmetric – are employed. Now, you might be wondering, ‘Why both? Shouldn’t asymmetric cryptography be used as it’s more secure?’ Granted, it is more secure, but it comes with a pitfall. A major drawback, when it comes to Public-Key cryptography, is the computational time. As the verification and functions are applied from both the sides, it slows down the process significantly. That’s where symmetric encryption saves the day.

First, when two parties (browser and server in the case of SSL) come across each other, they validate each other’s private and public key through asymmetric encryption. Once the verification is successful and both know whom they’re talking to, the encryption of the data starts — through symmetric encryption, thereby saving significant time and serving the purposes of confidentiality and data-protection. This entire process is called an SSL/TLS handshake. If you want to learn more about this handshake, here’s an excellent post for you.

## Using Asymmetric Encryption Without Even Realizing It

When you visit any HTTPS website/webpage, your browser establishes an asymmetrically-encrypted connection with that website. Your browser automatically derives the public key of the SSL/TLS certificate installed on the website (that’s why it’s called ‘Public Key’). Do you want to see what it looks like? Click the green padlock you see in front of our URL and go to certificate details. This is what it’ll look like:

30 82 01 0a 02 82 01 01 00 c2 d8 be ec a4 e1 52 20 7f 7f 7d 1a 17 38 99 17 ef 6a 9e af 66 89 67 5a 58 e2 b8 7c 76 f2 b8 c6 8f 98 e4 06 eb 3c 1c 04 34 1e 10 a9 42 c2 34 be 99 3b 98 7b 35 60 3a d5 41 bb 96 19 1a 3c 66 a0 75 77 64 2a 2e 19 42 5a b1 d0 1f 4d ac 32 2e af 4e 20 b8 89 07 83 51 21 e4 35 02 4b 10 45 03 37 ce 26 87 e0 b8 4d dc ba c5 e7 ae 60 68 b3 0c a3 5c 4f dd 30 1f 95 96 a5 2e e5 6f ae e8 e2 dc df 3a ab 51 74 82 f5 9e 15 3a ab 7c 99 3c 07 5b ad f2 88 a2 23 1c cd 41 d8 66 a4 90 0d 4a 23 05 5c de aa e3 82 13 f4 08 87 b3 34 08 6f 38 fb f8 84 ec 06 99 e0 ab 8a ab 1b 7c 99 fd 57 94 67 17 15 b7 27 67 c1 bc d1 a7 f6 c6 7e 01 63 02 0c 03 c4 bb 1f 70 0d db 27 ab 79 57 d9 92 35 f3 92 3c ad f4 fb f0 36 82 33 5a a0 f9 82 78 04 a6 e7 d6 ee 01 23 68 36 68 3b 41 fe 68 56 0b 6b 36 3b 83 b1 02 03 01 00 01

Amazing, isn’t it?

So, this key encrypts any information you send to our website during the initial handshake, and our Private Key will decrypt it. Do you want to see what our Private Key looks like? Here it is:

Oh wait, that’s the key to our office. Did we tell you that the Private Key is supposed to be “Private?” Yes, you should NEVER EVER give it to anyone, and keep it close to your chest (not literally). We recommend storing it at a location where only authorized people have access to it. If possible, you should try and save it on a hardware device that’s not connected to your system all the time.

## Conclusion

Still here? Good. We believe that now you (hopefully) know what asymmetric encryption is and how it protects you from the wrath of cybercriminals.

Topics:
web security, Security, assymetric encryption, encryption, public key, private key, symmetric encryption, cybercrime

Published at DZone with permission of Jake Adley.

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