Encryption and Decryption – What Are They? Why Are They So Important?

To really understand the concepts of encryption and decryption, you first need to understand cryptography in general.


In short, cryptography is the study and practice of all the classical encryption techniques that are used to protect and secure information while the information is traveling from one point to another or being stored somewhere.

Cryptography is commonly used to stop unauthorized individuals from accessing important information. Cryptography primarily uses two functionalities which are known as encryption and decryption.

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What Are Encryption and Decryption?


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Encryption is the process of converting information into a code. It enables the sender of a message to make the message unintelligible to everyone apart from the receiver.

Once a message or any other type of information goes through the process of encryption, it’s unrecognizable to anyone. It basically takes another form that has no resemblance to the message that the sender initially sent.

Encryption is very important for modern communication since it’s the most reliable way to make sure that a hacker or any other type of cybercriminal is unable to intercept and read the message.

There are many encryption techniques used today including image encryption as well as symmetric and asymmetric encryption.

Most of the time, encryption takes place with the help of key algorithms. We’ve already mentioned that encryption is the best way to keep any kind of data safe from hacking and other stealing operations, but it’s also true that plenty of companies use encrypted data just so their competitors can’t access their trade secrets.


Decryption essentially reverses the process of encryption so the receiver of the message can read and understand the sent message’s content. The process of converting encrypted text into decrypted text is typically simple as long as the receiver possesses the correct data encryption key. This is also true if data encryption is used on an image or any other form of data.

Once the encrypted data is decrypted, the receiver of the message can understand the message and act on the new information.

Decryption can use manual methods such as operating on the actual text or keys that the sender of the message uses to encrypt their message. It can also be done automatically by a computer.


An employer wants to send some sensitive documents to an employee for processing but can’t risk hackers getting hold of the documents and reading them. The employer can encrypt the documents and then send them to the employee who can then decrypt the documents using an employer-provided encryption key. They can then start working on the documents as they would normally.

More specifically, let’s say a document contains a top-secret word like “ALUMINUM.” This word could be encrypted with an algorithm that replaces each letter with the letter that follows it in the alphabet.

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So the “A” in ALUMINUM would become “B,” the “L” would become “M” and so on to give a cipher “BMVNJOVN.” Anyone who wants to know what the original message was must know the algorithm which was used to encrypt the original information.

This is a very simple example so one can easily tell what the original message was. In the real world, far more complicated algorithms are used to encrypt information.

In any case, the sending party would let the receiving party know the encryption key. In this case, the key is to replace each letter with the letter that follows it in the alphabet. Using this key, the receiving party would decrypt the message, read the contents and move on.

Encryption/Decryption Keys

Symmetric Key Encryption

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There are many types of encryption, one of which is symmetric key encryption. In this type of encryption, both the encryption and decryption processes use the same single key while working on the data.

The two parties that are in communication have to ensure that they’re able to exchange the encryption key via symmetric key encryption. Without it, the receiving party won’t be able to decrypt the information and understand its contents.


Symmetric key encryption is different from public-key encryption in the sense that in public-key encryption makes use of two keys. One is private while the other is public and both are required to encrypt and decrypt the data.

The symmetric key algorithm works differently and converts the data into a form that isn’t understandable to anyone except the party who has the secret key. Without the secret key, the data cannot be decrypted.

The symmetric key algorithm only reverses its encryption procedures when the receiver of the encrypted message who has the encryption key receives the message.

As for the key itself, it could be a simple code, a password or even some random combination of numbers and letters. These can be generated via RNGs or random number generators.

Of course, the actual strength of these keys is dependent on the activity in question. For example, for banking transactions, the industry typically requires the keys to be created according to the data encryption standard approved by FIPS 140-2.

Generally speaking, there are two kinds of symmetric key algorithms. These are the block algorithm and the stream algorithm.

Block algorithms, as the name suggests, encrypt a set length of bits in blocks of data with the help of the secret key. While encrypting the data, the systems keep the data in the memory until the blocks are completed. Stream algorithms work by encrypting the data as it streams without retaining it in the memory.

Asymmetric Key Encryption

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Asymmetric encryption is also known as public-key encryption and the reason for that is simple: it uses a pair of encryption keys. One is a public key and one is a private key. As their names would suggest, the public key is for anyone to look at and use while the private key is the secret key that only the receiver has access to.

For example, if Bob wants to send an encrypted message to Jim then Bob would take Jim’s public key and encrypt the message with that key. Jim, upon receiving the encrypted message, can use his private key to decrypt the message which Bob encrypted with Jim’s public key.

The benefit of using asymmetric encryption is that anyone can make their public key available for people to make encrypted messages with and then decrypt it using their private key.

Of course, symmetric key encryption has its advantages over asymmetric encryption as it requires less computation and can handle more data more easily.

The other thing to note here is that in public-key encryption anyone can decrypt your data if it was encrypted using a public key. This is why security experts generally warn against using public-key encryption for sensitive data.

However, that doesn’t mean it doesn’t have its uses. Many cryptography and electronic commerce applications require digital signatures and the best way to sign data is with one’s private key.

Encryption vs. Decryption

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The biggest difference between encryption and decryption is what happens to the data in question. Encryption makes data unreadable while decryption makes unreadable data readable by converting it back to its original state. However, there are some other subtle differences as well.

For example, when we’re talking about a person communicating with another person then the person sending the data has to encrypt the data. Once the data has reached its final destination, then the person who received the data has to decrypt the data.

Of course, neither of them really have to do anything themselves since there are specialized apps for both of these processes. In fact, if you’ve used Facebook Messenger or WhatsApp you’ve actually used these processes without knowing it.

With all the differences we’ve mentioned, it’s about time we mention a similarity as well.

The biggest similarity between encryption and decryption is that both processes essentially use the same algorithm and the same key.

Benefits of Encryption

  • It’s the best way to protect all kinds of data that demand confidentiality. Examples include usernames and passwords. Not only that, but it can also make any type of private information (such as medical records, bank statements and social security details) safe on a computer. Even if the computer gets hacked, criminals won’t be able to decipher anything of importance.
  • It acts as a seal of approval for the receiver of the message that the contents of the transferred file or any other document have been maintained and nothing has been altered by anyone.
  • Without it, there would be no way for companies and governments to protect their research and put an end to problems such as plagiarism and intellectual property theft.
  • It’s extremely helpful for people who want to communicate over a network like the internet. Recent years have seen hackers and government agencies becoming very skilled at breaking in and recording people’s conversations. These processes help prevent that from happening.
  • It allows the owner of a file or data to deny or grant access to anyone they want and keep everyone else from accessing it.

What Is an Encryption/Decryption Algorithm?

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Encryption and decryption algorithms are mathematical functions that perform whatever tasks they were designed to perform. The vast majority of the time, you’ll find that both the encryption and decryption algorithms are related functions but each performs its own action on the given information.

What Is Key Length?

If someone wants to break the encryption algorithm guarding some data then they have to find the right key which allows access to the encrypted data. When it comes to symmetric encryption, the hacker has to find the key that was used to encrypt the data. In the case of public-key encryption, the hacker has to know the secret information that the two parties shared with each other to break the algorithm.

The brute force method to break an algorithm is to try all possible keys until the right one unlocks the data. In the case of public-key encryption, the hacker already has access to half the key since it’s public. The hacker can try to derive the other half, the private key, by carrying out mathematical calculations.


A brute force attack is the act of manually finding the key. When we talk about the key strength of any given algorithm, we’re actually talking about the fastest time it takes to break that algorithm compared to a brute force attack.

This is where the length of keys becomes important for symmetric encryption. Longer keys offer more security than shorter ones.

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Key length is usually expressed in bits. The symmetric key encryption RC4 uses a 128-bit key. The way different ciphers work means that the same key length can provide a higher or lower level of protection depending on the cipher itself.

For example, RSA public-key encryption uses 1024-bit keys. On the other hand, some symmetric key algorithms can offer the same protection as the RSA with a key length of just 80 bits.


Encryption is an important process that converts data into an unreadable form. Decryption reverses all that and changes it back to its readable original form. These processes are very important for keeping confidential data such as usernames and passwords safe from hackers.

Users have the option of using different types of encryption such as symmetric and asymmetric. Both have their own advantages and disadvantages so which one is used depends on the needs of the user in question and the task at hand.


Can encryption be decrypted?
Yes, but you’ll need the key with which the data was encrypted.
Where is encryption/decryption used?
These processes are used on data that either needs to be transferred, stored or accessed safely and privately.
Ali Qamar Ali Qamar is a seasoned blogger and loves keeping a keen eye on the future of tech. He is a geek. He is a privacy enthusiast and advocate. He is crazy (and competent) about internet security, digital finance, and technology. Ali is the founder of PrivacySavvy and an aspiring entrepreneur.
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