Asymmetric Encryption Explained in 5 Minutes or Less

Data is precious, and in the wrong hands, it can cause harm to an individual, third party, or organization.

That’s why we have encryption, a way to secure the data for storing or during data transfers across the internet. 

And in this article, we’ll take a look at Asymmetric encryption.

Let’s get started.

What is Encryption?

Encryption is the computational process of converting data to a hard-to-decode format (also known as cipher text). It relies on a robust computation encryption algorithm.

So, you ask computers to scramble data for secure storage or transfer. It also means that only authorized parties can access the data.

At the core of encryption, you have cryptographic keys. They have mathematically generated keys, calculated based on other encryption parameters and based on sender and receiver agreement.

Let’s take an example of simple encryption.

So, you (let’s name it Bob) want to send a message to John, your internet buddy, who likes cipher texts.

Bob writes the message and then runs the data through “encryption.” The encryption algorithm they’re using is simple. First, Bob shifts the ASCII value by 4 points and creates the cipher text. 

So, “A” ASCII values become 65 to 69, which returns a matter of “E.” In ASCII, E has a value of 69. Following this simple method, Bob creates a message and sends it to John.

As John and Bob have already agreed on how to encode and decode, they can send messages to each other.

So, if Bob writes, “Hello, John,” its cipher text will return “LIPPS0$NRLR”.

The process of decoding the message that Bob sent is known as decryption.

To make sense of it, check out the ASCII table.

Also read: Best Text to ASCII Converters You Should Try

What Is Asymmetric Encryption?

Asymmetric encryption (also known as asymmetric cryptography) is public-key encryption. Here, the algorithm carries out encryption and decryption with the help of two pairs of keys:

• Public key: The public key helps in message encryption.
• Private key: The private key helps in message decryption. The private key is also known as the secret key as it is non-sharable and kept confidential by the owner.

So, how does asymmetric encryption work?

Let’s bring back Bob and John from our previous example.

Bob knew that his method of sending encrypted messages to John was not secure. After all, anyone can easily brute-force the encryption.  

And that’s why he choose asymmetric encryption to send his messages to John.

In that case, Bob first asks for John’s public key. Then, as he already knows John, he can ask him personally. 

Otherwise, there are Public Key Directory (PKD) from where entities can register and share their public key. This way, anyone who wants to send a secure message must get hold of that person’s public key.

Now, Bob can use asymmetric encryption to encrypt the message with the sender’s public key, in this case, John’s public key. 

John receives the message and can decrypt it using his private key.

On the other hand, the other way around is also possible. That means the data can be encrypted and decrypted using a private key.

So, if Bob encrypts the message with his private key, John can decrypt it using Bob’s public key!

Asymmetric encryption works because you need access to two keys for it to work. This is different from symmetric encryption, where both encryption and decryption are carried out by one key. 

How Does Asymmetric Cryptography Work?

To get a clear understanding of how asymmetric cryptography, we need to see how it works.

The underlying process depends heavily on an algorithm that uses a well-prepared mathematical function. The function handles the key pair generation.

However, the key generation varies depending on the agreement between the sender and receiver. 

Also, most tools and programming languages already have pre-defined libraries to handle cryptography. So if you opt to code asymmetric cryptography, you’ll need to use those libraries and not waste time re-inventing the wheel. 

The common process that takes place when a person decides to send an encrypted message to another person is as below:

➡️ The sender and receiver generate public and private keys based on some parameters.

➡️ Next, the sender looks for the receiver’s public key in the public-key directory.

➡️ With the public keynoted, the sender uses it to encrypt the message.

➡️ He then sends it to the recipient, who decrypts it with their private key.

➡️ The receiver can decide to reply to the message, and the same process retakes place (just in reverse).

Asymmetric Encryption Pros

Asymmetric encryption offers plenty of advantages. These include:

• Message authentication: Asymmetric encryption offers excellent message authentication, which allows verifying a message and its sender. That’s why digital signatures are one of the best use cases of asymmetric cryptography. 
• Convenient: Implementing asymmetric encryption is convenient as key distribution is easy and accessible. The public keys are easily accessible, so senders can easily encrypt a message with the receiver’s public key. On the other hand, the receiver can decrypt the message with his private key.
• Detects tampering: Asymmetric cryptography also detects any form of tampering during transit.
• Allows non-repudiation: Works similar to physically signed documents and hence cannot be denied by the sender.

Next, we will discuss the cons of asymmetric encryption.

Asymmetric Encryption Cons

The disadvantages of using asymmetric encryption include:

• Slow: Asymmetric encryption is slow, hence not ideal for transferring vast data.
• Non-authenticated public keys: It offers an open model where the public keys are accessible freely. However, there is no way to verify the general key authenticity and its association with an individual. This gives the burden of verifying its authenticity to the user.
• Non-recoverable private key: There is no mechanism to recover the private key. If it is lost, the messages can never be decrypted.
• If the private key leaks, it can compromise security: If the private key gets compromised, it can lead to data or message leaks. 

Now, we will explore some of the use cases of asymmetric encryption.

Asymmetric Encryption Use-cases

#1. Digital Signatures

Digital Signatures are common nowadays. They use the Rivest-Shamir-Adleman (RSA) algorithm. It generates two mathematically connected keys: public and private. This way, the digital signature is created using a private key and can be easily verified or decrypted using the signer’s public key.

#2. Encrypted Email

Emails can be securely sent through the internet. The email content is encrypted with the public key and decrypted with the private key.

#3. SSL/TLS

SSL/TLS is a secure protocol for communicating across the network. It uses symmetric and asymmetric encryption to create a secure connection between sender and receiver.

In most cases, it uses symmetric encryption. Still, it might need to use asymmetric cryptography when both parties generate their session keys, requiring asymmetric encryption to verify the origin server’s identity.

#4. Cryptocurrencies

One of the most common use cases of asymmetric cryptography is cryptocurrency. Here, the public and private keys are used to do encryption.

The public-key cryptography works well with crypto as the public key is made available for transfer, whereas private keys work to unlock transactions and receive cryptocurrencies. Popular crypto that uses asymmetric encryption includes Bitcoin.

#5. Encrypted Browsing

Browsers can also use asymmetric encryption to secure your data during transfer. For example, after you open your browser and go to a site, you’ll notice the HTTPS protocol ahead of the URL. The ‘s’ here means secured. To achieve a secured connection, the browser handshake to the server, where both parties decide how to encrypt the data.

Browsers can use both symmetric and asymmetric encryption to carry out the handshake. However, asymmetric encryption makes it easy to create secure connectivity.

In real-world scenarios, browsers are smart enough to use both types of encryption to achieve secure connectivity.

#6. Sharing Keys for Symmetric Key Cryptography

Asymmetric key encryption also acts as a way to share symmetric keys across a connection.

Symmetric Vs. Asymmetric Encryption

The differences between symmetric and asymmetric are as below.

When to Use Asymmetric Encryption?

You should use asymmetric encryption when:

• You’re looking for a more secure option for message encryption and sending.
• You’re sending small amounts of data as asymmetric encryption is slow and unsuitable for large data transfers.
• You’re looking to confirm digital signatures.
• You’re working with cryptocurrencies and want to authorize transactions by confirming identity.

Final Words

Asymmetric encryption is at the core of different technologies. You’ll find many uses, be it TLS/SSL to verifying digital signatures.

Moreover, thanks to already available cryptography libraries, you can quickly implement asymmetric cryptography in your preferred tool and programming language. You don’t have to reinvent the wheel and write asymmetric cryptography yourself.

Next, check out a detailed article on symmetric encryption.