# What is RSA Algorithm?

When you transmit any sensitive information across the internet, you need to be extremely cautious as the information is vulnerable and prone to attacks. The information can be intercepted by a middleman and tampered with easily. This is why enterprises across the globe focus greatly on cybersecurity, especially those that handle millions of transactions on a daily basis.

Whenever we talk about cybersecurity, it’s hard to ignore the terms encryption and decryption. To the unversed, encryption is the process of translating plain text data into a piece of ciphertext that appears to be totally random and meaningless. Decryption is the process of converting the ciphertext and plain text.

Now, the RSA algorithm is an asymmetric encryption algorithm that is widely used to protect sensitive data. But what is asymmetric encryption, and how does the RSA algorithm use it to protect your data. We have answers to all your questions in this post.

**Table of Contents**

- What is an asymmetric key algorithm?
- What is the RSA algorithm?
- How does the RSA algorithm work?
- Advantages of the RSA algorithm
- How secure is the RSA algorithm
- Winding Up

## What is an asymmetric key algorithm?

Before we get into the RSA algorithm, it is important to understand what an asymmetric key algorithm is. Asymmetric key algorithms are generally referred to as public-key algorithms. It uses a pair of related keys called public and private keys for encryption and decryption of data. Asymmetric encryption takes plain text and converts it into an unreadable format called ciphertext using complex mathematical functions.

The data from the sender is encrypted using a public key. Even if the public key is intercepted, the attacker cannot decrypt the data. This is because the private key is used to decipher the information from the sender. The private key is only stored on the authorized receiver side. With that basic knowledge about keys, let’s move on to the RSA algorithm.

## What is the RSA algorithm?

RSA (Rivest-Shamir-Adleman) is a popular asymmetric cryptographic algorithm that revolves around a simple mathematical concept of primary numbers. We all know it is very difficult to factorize a large integer. The public key in RSA consists of two numbers where one number is the multiplication of two large prime numbers. The private key is derived from the same pair of prime numbers.

Now, you might wonder, what if the attacker factorizes the large prime number and get hold of the private key? It totally depends on the encryption strength, which, in turn, depends upon the key size. When the key size is doubled or tripled, the encryption strength increases exponentially.

## How does the RSA algorithm work?

When you use RSA for encryption, you convert the plain text at the sender’s endpoint to a large number raised to very high power.

Then the public key value (which acts as a divisor) divides the large number, producing a remainder. This is the end value of your encryption. Now the plain text is successfully encrypted and sent to the authorized receiver.

Now, remember that the public key is public, i.e., it can be intercepted and modified by anyone. But intercepting the public key cannot give you the original text. This is because the ciphered text can be deciphered only by the private key available at the receiver’s side. This is why the RSA algorithm is preferred over other AES algorithms due to its reliability.

At the receiving end, the owner of the private key raises the number he received, which is the above-mentioned encrypted value, to the power of the private key value available at the recipient’s end. Then this large number is again divided by the public key value, which gives a remainder. The remainder is the original number that you had when encrypting the plain text. With the original number, the deciphered text can be traced back to the original text.

In a nutshell, the RSA algorithm comprises 4 steps -

- Key pair generation
- Key distribution
- Encryption using a public key
- Decryption using both private and public key values

## Advantages of the RSA algorithm

- RSA overcomes the weakness of all the symmetric algorithms in terms of authenticity and confidentiality.
- It is faster than DSA(Digital signature algorithm) for encryption.
- Cracking the RSA algorithm is very difficult as it involves complex mathematical calculations.
- It is very easy to implement. Also, sharing public keys with users is easy.

## How secure is the RSA algorithm?

RSA algorithms are widely adopted in large enterprises to secure communication between endpoints. A report reveals that it will take approximately around 70 years for attackers to decipher the key value if the key’s weight is 100 digits. RSA keys are typically 1024 or 2048 bits long. As encryption strength depends upon the key size, it is recommended to max out the value and use at least 2048 bits. Security experts think that the 1024-bit key size can be cracked in the near future.

## Winding up

RSA is currently the most reliable cryptographic algorithm out there. It is adopted by organizations handling sensitive communications and transactions between endpoints. From healthcare to banking, RSA has found a place in almost all industries. However, some cybersecurity experts believe that in the future, quantum computers can be programmed to break the RSA algorithm by deciphering the private key value.