# Cryptography – All You Need To Know About It

Find out what is cryptography, its types and principles. Learn about Encryption, Decryption and Steganography along with Symmetric and Asymmetric keys.

Nowadays, encryption has become an essential part of the IT industry. It has become so crucial that every one of us has once come across the term. Encryption helps us to secure our data or information from third-party access during communication or even while storing that data. In this article, we will study about cryptography; we will discuss how it is crucial for the IT industry and how it works.

## What is cryptography

By definition, “Cryptography is the practice and study of techniques for securing communication and data in the presence of adversaries.” Basically, Cryptography is done to avoid any third party for the public to read some private messages. The whole process of cryptography is all about constructing and analyzing some protocols involving securing the data.

So to make you understand why Cryptography is important, let us begin with an example. Let’s say we have a person named Daniel. Daniel sends a message to Ella, who resides in the other part of the world. Let’s say Daniel sends this message through WhatsApp. Obviously, he wants to keep his message secured. But there is another guy, a smart one; named Johnson. He tries to access the message sent by Daniel to Ella secretly. Johnson, since he has access to complete communication, can do a lot many things. Apart from just knowing what Daniel actually wants to tell Ella, he can also manipulate information for his own gain. And at the same time, he can also access some very private information. Sometimes when a third party gains access to your information, the result could be catastrophic. This is where encryption or cryptography becomes important.

Cryptography has been used ever since the beginning of politics in the human race. Now, the technique of cryptography has become advanced since the development of rotor cipher machines in World War One and the use of computers in World War Two. The modern cryptography is almost wholly based on mathematics and computer science knowledge. In today’s time, the information is tough to break by any third party.

Let us come to the example of Daniel, Ella and Johnson. To send his message securely, Daniel will first convert his simple message to an unreadable form. It is mostly in the form of numbers. A key is used to convert this message to this unreadable form. And this key is known as ciphertext.

So, Daniel sends this encrypted message to Ella and then doesn’t worry about its security. Why? This is because even if Johnson is able to get access to what he has sent, he will not be able to process the information. And the recovered text will simply be useless for him. Now when Ella receives the message, she will have that particular key to decrypt the received message. This key will only work when the message sent by Daniel was utterly safe without any alterations. Now, let us suppose that when Johnson was able to get access to the message, he managed to alter the codes. In this case, Ella’s device will not be able to decrypt a message and will show an error.

## The need for Cryptography

1. Let us have a look at the importance of cryptography-
2. Cryptography helps the user to protect the confidential data such as account numbers, passwords, user IDs etc
3. It provides confidentiality to some highly private information
4. With encryption, you can prevent plagiarism to a large extent.
5. It helps both the receiver and the sender to ensure that the message sent during the communication has not been altered or accessed by the third party.
6. With the help of cryptography, you can protect highly private or sensitive information from the public or hackers.

## Encryption and decryption

Encryption and decryption are two essential processes in the world of communication today. They are included in Cryptography only.

### Encryption

When a person writes the message, he first converts it to an unreadable form, or we can say a nonsense text. This is done with the use of an algorithm following a particular rule which is shared only to the receiver. This is the process of encryption.  Here, the system of the sender, or the sender himself, transforms the original information into an unrecognizable format. This is the reason why most of the hackers or third parties are unable to recognize the message even if they hack it midway. Nowadays, some companies also encrypt their data to keep it safe from rival companies.

### Decryption

When the receiver receives the encrypted information, hi uses the same algorithm used to encrypt the message to convert it into the original readable form. This is basically done by using the same algorithm keys which were used to convert the original message to an unreadable form. This whole process converting the encoded for the encrypted data in a form that is readable and understood by the human or a computer is called decryption. This is generally done by the system of the receiver or for the receiver himself.

### Kerckhoffs’s principle on cryptography

Kerckhoffs’s principle on cryptography stresses on the fact that the cryptographic system should be able to secure the data even if all the details, except for the key is publicly known.

To explain it in other words, the principle says that after the message is encrypted using a cryptographic, the message should be secured even if the Intruder gains complete access to the encrypted message and has comprehensive knowledge of what kind of algorithm is used to encrypt it. This means that the security of the data sent in communication from the sender only depends on the key used for encryption. This is because all the algorithms used in Cryptography are public.

## Steganography vs cryptography

Steganography and Cryptography are two different types of methods to secure the data and the privacy related to it. The former hides the information making the hackers or intruders believe that no communication has ever taken place. In contrast, Cryptography takes the help of encryption to convert the message in the form of codes.

### What is Steganography

By definition, “steganography is a technique of wearing communication by cancelling the secret message into a fake message.” Disturb, steganography is derived from a Greek word, which means “covered writing”. The primary purpose of steganography is not to let the hackers know that there is any kind of communication in the process.

Earlier, when there was no computer, people used invisible ink, pencil impression on the handwritten characters, pin punches etc. to convey a message with the help of steganography. One of the simplest methods of hiding that sent message was to create a message in which only a few significant characters used to contain the secret message? You must have seen this use of steganography in many movies.

### Differences between steganography and Cryptography

1. Steganography is all about covering for hidden writing, whereas Cryptography is all about secret writing.
2. In steganography, the main attempt is to make the communication undetectable. Whereas, in Cryptography, the main intention is to let only the receiver read the information.
3. In Cryptography, even if the communication gets in the hand of the third party, he may not be able to retrieve the correct information until and unless he has the key. But this is certainly not the case with steganography.
4. Nowadays, Cryptography is widely used among almost everyone, whereas steganography is losing his popularity because of being outdated.
5. The main structure of the message is not changed in steganography. In the case of cryptography, the whole structure is changed and can only be retrieved with the help of a key.
6. The principles of security provided by steganography are only confidentiality and authentication. On the other hand, cryptography principles include confidentiality, integrity, authentication and nonrepudiation.
7. The method of steganography can be used on any medium like image, audio, video and text, but in the case of cryptography, we can use the technique only on text.
8. The method used to decrypt encrypted code in the message in Cryptography termed as cryptanalysis. Whereas, in the case of steganography, the process of detecting the presence of a message is called steganalysis.

### Who wins?

Steganography deals with hiding the communication. It fails if the third party is able to identify the presence of steganography. He will then be able to retrieve the whole message completely. This is not the case with cryptography. In cryptography, it is all about changing the complete structure of the additional message, and then sending it. Now, even if the third party man gets access to the whole message, he will not be able to identify and decode it. Cryptography will feel when the third-party will get access to the key to retrieve the information.

## Principles of cryptography

1. Confidentiality – No third party can access the information except for the person who is the intended receiver.
2. Integrity– If the hacker is able to get hold of the message, he will not be able to make changes in the information. In case of any change, the decoder from the receiver site will show an error.
3. Non-repudiation– Once the creator of the message or the sender sends the message to the receiver, he cannot deny his or her involvement of sending the message in the later stage.
4. Authentication– The identities of sender and receiver(s) are known and confirmed, and the destination or origin of the information is confirmed too.

## Types of cryptography

### Symmetric Key Cryptography

During communication, in symmetric-key Cryptography, the sender and the receiver share the same key for coding and decoding the messages. The only thing the sender and the receiver have to make sure before the communication is that the key is shared in a secured manner. So this is the weakest link of this kind of encryption. The sender has to make sure that the key is sent to the receiver with complete security and authenticity. If the hacker can get access to the key which is being used, he can easily decrypt the whole encrypted message, thus making fun of the complete Cryptography method.

### Asymmetric key Cryptography

Here, two different types of keys are used to encrypt and decrypt the message. During encryption, the sender uses the public key which is available to the public. Whereas during decryption, the receiver uses a private key which is exclusive to him. So even if the public is aware of the encryption key, only one person who has the private key can decode the message.

### Combination of symmetric key and asymmetric key operations

We can see that both symmetric key and asymmetric key have drawbacks. Thus, it’s advisable not to use each of these methods individually. However, it is safe to use a combination of both symmetric key system and asymmetric key system. Generally, the secret key in the symmetric key system can be used together with the public key technique.

The symmetric key method helps the receiver to decode the message faster, and at the same time, the public key provides a safe passage to send the secret key to the receiver. To conclude, we can say that these methods can be used to convert the original message into unreadable form efficiently. And then with the combination of symmetric key technique and asymmetric key technique, we can transform the encrypted message into to the original one quickly with proper security. Apart from providing protection to the message and communication, these two systems also offer an additional benefit like quickly finding the user’s identity and ensuring that the data received has not tampered.

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