What is asymmetric encryption, and how does it work? What is asymmetric encryption and how does it work? As the world becomes more digitised and paperless, these two questions are becoming more popular. When all is saved on machines, however, data security becomes a major concern. Hackers can steal data from your computers, emails, cloud networks, and USB drives, as well as when you move it over the internet from one location to another.

Encrypting data is one of the most successful ways to keep it secret. And it’s here that asymmetric key encryption, also known as public key encryption, comes into play. We’ll describe asymmetric key encryption and address the question “how does asymmetric encryption work?” in layman’s terms in this article. Later on, we’ll look at the advantages and drawbacks of this form of encryption.

What Is Encryption?

Before we can address the question, “What is asymmetric encryption?” we must first define it. First, let’s go over the concept of encryption in general.

Encryption, in its most simple form, is the use of “fancy math” and a collection of instructions (algorithms) to mask and protect data. These algorithms scramble plaintext data into ciphertext, which appears to be gibberish unless a special key is used to decode it. This ensures that once data has been encrypted using a cryptographic algorithm, the ciphertext cannot be decoded or used to guess the data’s original material. As a result, your information is safe from prying eyes.

Let’s consider the following example to see how encryption works in a general sense:


You can see how encryption algorithms and decryption keys shift the data from plaintext to ciphertext and back to plaintext in this example. The keys may be symmetric (identical) or special (unique) (asymmetric).

When we talk of encryption, we’re comparing it to a door lock. A key is required to operate the lock. This means that only the person who has the key to the door can open it and gain access to whatever it’s guarding. A key in the digital world can be anything from a password to a code to a PIN to a complex string of computer-generated characters.

An Overview of the Two Types of Encryption

Encryption can be divided into two types:

1) Symmetric encryption: This form of encryption is reciprocal, meaning it encrypts and decrypts data with the same key. This works well with massive data sets, but it has problems with key delivery and management.

2) Asymmetric encryption: This method of encryption encrypts and decrypts using two different keys: a public key and a private key. We’ll go into asymmetric key encryption in greater depth later.

We’re going to concentrate solely on asymmetric encryption in this post. Another post on symmetric encryption will be published in the coming weeks, so stay tuned. In the meantime, we have an article that will help you discern asymmetric encryption from symmetric encryption.

Now, let’s talk about why you’re here in the first place…

What Is Asymmetric Encryption? Explanation and Definition

Asymmetric encryption is a form of encryption that encrypts and decrypts data using two different but mathematically related keys. The public key encrypts information, while the private key decrypts it. It’s also known as public key encryption, public key cryptography, and asymmetric key encryption because of this.

Everyone has access to the public key. It is open to the public and can be used to encrypt data. When encrypted, however, the data can only be decrypted with the corresponding private key. To avoid being hacked, the private key must be kept secret, as you would expect. As a result, the private key is only accessible to the authorised person, server, machine, or instrument.

What Does Asymmetric Encryption Do?

Asymmetric encryption helps you to verify third parties you’ve never met using unreliable public networks. Unlike conventional (symmetric) encryption methods, which rely on a single key to encrypt and decrypt data, asymmetric key encryption employs two distinct keys.

This is why public key encryption is regarded as a vital component of internet security’s base. Public key infrastructure (PKI) is a set of policies, procedures, and technologies that enable secure third-party internet communications. It uses both asymmetric and symmetric encryption to accomplish this.

You can use asymmetric encryption methods to:

  • Authenticate parties,
  • Verify data integrity, and
  • Exchange symmetric keys.

The majority of data encryption is done using symmetric encryption.

You may not know it, but you’re currently using public key encryption! Do you see the HTTPS in the website URL or the protection padlock icon in your browser? You’ve linked to a website that uses SSL/TLS certificates and the stable TLS protocol if you see any of those elements. This uses asymmetric key encryption to verify the server’s identity and generate symmetric session keys. (After that, your browser and the web server will use symmetric encryption for the remainder of the session.)

As you can see, asymmetric encryption works in conjunction with symmetric encryption which is what allows it to be used over the internet.

Four Main Characteristics of Asymmetric Encryption

1. Asymmetric Encryption Is Designed for Securing Data & Key Exchanges in Public Channels

In a nutshell, the aim of asymmetric key encryption is to provide a safe way to encrypt data in public channels while still ensuring data integrity and authentication. Since it doesn’t include the exchange of keys, it doesn’t have the key distribution problem that symmetric encryption does.

2. Asymmetric Encryption Keys Are Large

Asymmetric public and private keys are long strings of random numbers that are unique. For example, despite the fact that millions of websites use SSL/TLS certificates, each one has its own set of public and private keys. However, in order for keys to be strong and stable, they must be created with a high level of entropy (randomness). Each key must be so random and unpredictable that guessing it will take thousands of years on modern supercomputers.

Consider the following asymmetric public and private key examples:

-----END PUBLIC KEY-----

3. Public Key Encryption Algorithms Are Strong

Diffie-Hellman, RSA, ECDSA, ElGamal, and DSA are common asymmetric encryption and key exchange algorithms. Although it is not a strict law, asymmetric encryption often employs long keys of 1024 bits, 2048 bits, or more. Encryption is usually more reliable the larger the key size.

There are 22048 possible combinations if the keys are provided with 2048-bit encryption, for example. It will take thousands of years for modern supercomputers to go through all of the possible combinations to find the corresponding private key of a public key. In short, particularly when keys are long, you can’t guess the private key from the public key.

4. Asymmetric Encryption Is a Resource-Hogging Process

Since those big keys need a lot of processing power, encryption takes longer. In other words, the encryption and decryption processes take longer since the key sizes are larger and two different keys are used.

As a result of its latency and processing requirements, asymmetric encryption is ideally suited to encrypting small chunks of data. It will put more strain on your servers if you use it for large blocks of data. It’s often used to set up encrypted communication networks that can then be used to allow data sharing using symmetric encryption.

How Does Asymmetric Encryption Work? Let’s Look at an Example of This Definition.

Let’s start with a hypothetical example to better understand asymmetric encryption.

Consider how you’d like to secure a valuable jewellery box that you’re sending to your significant other in the mail. You use a special lock that involves two number combinations to keep it safe when in transit. One number (the one you have) will lock the box, while another number combination will open it (which your recipient has).

You begin by putting the things you want to protect inside the box. The package is then locked with a special number combination before being mailed. When it arrives, the significant other unlocks the package and accesses the contents using her number combination. Since she never tells anyone about her phone number and keeps it to herself, no one else can use it.

Let’s use this knowledge to better understand how asymmetric encryption functions in the context of public key infrastructure.

All data sent over the internet is sent in plaintext. Anyone who obtains access to it would be able to read and understand it. Of course, using a private key, you can now encrypt the data. You can’t decrypt the data using the same key until it’s been converted to ciphertext. Only the corresponding private key will decrypt the ciphertext. The sender must have access to the public key, and the receiver must have access to the private key that corresponds to it.

How Public Key Encryption Helps You Protect Your Business & Data

Let’s look at a real-world example of asymmetric key encryption.

Digital Signatures Ensure Data Integrity

A digital signature is a mathematical algorithm that can be used to verify the validity or credibility of documents, emails, or other data. What it does is notify the recipient of a digitally signed document or email of any tampering or unwanted changes that have occurred. Asymmetric encryption and a cryptographic function known as hashing are used in digital signatures.

Later on, we’ll go into the basics of digital signatures and hashing. For now, just know that asymmetric encryption is used to enable digital signatures in the following applications:

  • Code signing certificates,
  • Document signing certificates, and
  • Email signing certificates.

SSL/TLS Certificates Secure Your Website

When a user opens your website in a browser (your web client), the browser initiates an SSL/TLS handshake. This handshake uses asymmetric encryption to authenticate the server to your client by sending its SSL/TLS certificate and public key. After that, the browser creates a pre-master password, encrypts it with the server’s public key, and sends it back to the server. The server then decrypts it using the private key that corresponds to it. The master secret (a shared secret) and identical session keys are then created by the two parties working together.

The session keys are symmetric, and they are used by both the client and the server for all data exchanges during that session. While the session key is in transit between the browser and the server, no attacker can decrypt or guess it. In man-in-the-middle attacks, this helps to prevent the data from being intercepted and read (also known as MitM attacks). As a result, the procedure begins with asymmetric encryption and then switches to symmetric encryption for the majority of the data transfer.

Personal Authentication Certificates Offer Client Authentication & Email Security

A personal authentication certificate, also known as a client certificate, is used to verify the identity of users within an organisation. You may use these types of certificates to limit access to sensitive data or systems to just a few people. These certificates are mounted on end user devices to provide access control and passwordless authentication. Employees can only access certain services if they log in from a certificate-enabled office computer.

Only workers are allowed to use those tools, email clients, and websites (such as intranet sites, production and testing sites, or even the admin pages of public-facing sites). Furthermore, restricting outsiders’ access to these web pages is often a smart idea. A personal authentication certificate and asymmetric encryption come in handy in this case.

The Advantages & Disadvantages of Asymmetric Encryption

We’ll look at some of the advantages and drawbacks of asymmetric key encryption in contrast to symmetric encryption in this section. However, if you want a more thorough comparison, see this article: The two types of encryption are symmetric and asymmetric.

Four Advantages of Asymmetric Encryption

1. It’s More Secure Than Symmetric Encryption

Asymmetric cryptography is more reliable than symmetric cryptography since it uses two connected but separate keys. This is due to the fact that asymmetric encryption uses longer keys (1028 bits, 2048 bits, 4096 bits, etc.) than symmetric encryption (128 bits, 256 bits, etc.)

2. It’s Useful When More Endpoints Are Involved

Only one key is exchanged by all endpoints in symmetric encryption. This means that the success of the operation is contingent on the key’s confidentiality. The chances of being exposed increase when a large number of endpoints share the same key.

In asymmetric encryption, however, only the designated recipient has access to the private key. When a single endpoint holds the private key rather than several, the chances of compromise are greatly reduced. As a consequence, when a large number of endpoints are involved, asymmetric key encryption works best.

3. Makes Key Distribution Easy

Since you don’t have to think about the public key’s protection in asymmetric encryption, you can spread it to a wide number of endpoints.

In symmetric encryption, on the other hand, the key must be distributed with extreme caution. When there are millions of servers and devices involved, symmetric encryption key distribution becomes incredibly difficult, and the chances of compromise increase.

4. Makes Digital Signatures Possible

The whole definition of digital signatures and how they operate relies on asymmetric encryption. When people talk about digitally signing a document, they’re actually applying a check-sum to it using a hash (a fixed-length piece of data that serves as a one-way cryptographic function). Essentially, this informs the recipient whether the contract has been changed or updated since it was signed. Asymmetric key encryption is used in digital signatures to achieve this.

The sender encrypts the message by using a hash as a check-sum and signing it with their private key. The receiver will use the sender’s public key to decrypt the digital signature and use the same feature to validate the hash value.

Two Disadvantages of Asymmetric Encryption

1. Slower Speed

It becomes a time-consuming operation because the keys are longer and the server must measure two separate keys for encryption and decryption. It also employs more advanced algorithms. Asymmetric key encryption is slower than symmetric encryption for a variety of reasons.

2. It’s Too Bulky to Be Used at Scale

The encryption and decryption process puts a significant burden on the server due to the two different long encryption keys. When a large amount of data is involved, asymmetric encryption cannot be used; otherwise, the servers would become overworked and slow.

This is why, for example, asymmetric key encryption is used during the SSL/TLS handshake process before switching to symmetric encryption for the data transfer between a user’s browser and a website during their session.

Wrapping Up on Asymmetric Encryption

While asymmetric encryption and its algorithms aren’t perfect, they’re still extremely useful for establishing safe communications with third parties over public networks. As a result, certain certificates use a hybrid strategy, using all forms of encryption at the same time. All data transmission in the SSL/TLS certificate, for example, is achieved using symmetric encryption. However, asymmetric encryption is used to submit the symmetric key.

Finally, we’d like to point out that asymmetric encryption is ideal for sending small amounts of data to a large number of endpoints. It’s a key component of digital signatures, and it’s much more stable than symmetric encryption.

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