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**Cryptography Explained**

Image Credit: Google Image & The Economist |

**Cryptography**is the branch of

**Computer Science**that deals with applying mathematical techniques to information security to maintain authentication, integrity, and confidentiality of data. It also prevents and detects malicious activities.

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**Services of Cryptography:**

Cryptography is mainly used to provide the following services:

**Confidentiality**is a service provided by the cryptography to make sure that data is secure and to make sure that the data is accessible to those who have access to it.

**Data Integrity**is another service from

**cryptography**that is useful in detecting data manipulation by unauthorized parties. Manipulation of data may be insertion, deletion or modification of data.

**Authentication**, a service from cryptography that is useful in the identification of entities transferring data and is responsible for the safe transfer of right data.

**Non-repudiation**is a service from cryptography that prevents entities from denying previous commitments or actions.

**Terms used in Cryptography:**

To understand the

**cryptography**, the knowledge on following terms is useful.**Plain Text:**Original Message is known as plain text**Cipher Text:**Modification or encoding of the original message using some mathematical techniques is known as ciphertext.**Encryption:**Process of converting plaintext to ciphertext is known as Encryption.**Decryption:**Process of converting ciphertext to plaintext is known as Decryption.**Cryptanalysis:**Processing of decrypting a message without any knowledge on the process of encryption is called Cryptanalysis.**Cryptology:**Areas of Cryptography and Cryptanalysis are together known as Cryptology.

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**Working of Cryptography:**

A cryptographic algorithm is nothing but a mathematical function that is used to encrypt or decrypt data. The cryptographic algorithm is known as cipher.

To convert plain text to cipher text, an

**algorithm**is used which may be a number or key. The security of the**algorithm**depends on the strength of the key used.**Cryptography algorithm**, keys, and protocols that are used for cryptography are together called

**Cryptosystem**.

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**Example of the Cryptographic algorithm:**

A simple example of the cryptographic algorithm is Caesar Cipher that uses simple mathematical operation for encryption and decryption.

### The algorithm works as below:

Let us represent the list of alphabets with numbers from

**0-25**. Here, the key is the number. Choose a key between 1-25.
Let us take Sample plain text as

**“Hello World”**and the key is 3. For example, alphabet A is represented as D which is obtained by shifting right to the 3rd letter as the key is 3.
The cipher for plain text

**“Hello World”**is**“Khoor Zruog”**. In the Decryption process, the shifting is done to the left side.###
**Types of Algorithms used in Cryptography:**

There are various algorithms used for cryptography. Some of them are as below:

**Symmetric Algorithm:**Cryptographic algorithm that uses the same key for both encryption and decryption are Symmetric algorithms.**Asymmetric algorithms:**It is also known as Public Key Cryptography. These algorithms use a pair of mathematically related keys for encryption & decryption known as a public key and private key. Public keys are shared but private keys are kept secret.

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**Examples of Symmetric Algorithms:**

**Data Encryption Standard(DES):**An Cryptographic algorithm that uses 56 bit key for encryption and decryption which is widely used**Advanced Encryption Standard(AES):**Cryptographic algorithm more secure than DES and uses keys of length of 128, 192 and 256 bits**International Data Encryption Algorithm:**An Cryptographic algorithm that uses the 128-bit key that has its application in**Open PGP also.**

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**Examples of Asymmetric Algorithms:**

**Diffie Hellman**is an Asymmetric algorithm that provides secure encrypted communication by exchanging keys using physical channel**RSA(Rivet-Shammir-Adlemen)**is another Asymmetric algorithm that uses keys based on the factorization of prime numbers concept**Elliptic Curve**is a famous and widely used Asymmetric algorithm that is based on the concept of elliptic curves over finite fields.

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**Free Resources to Learn Cryptography:**

**Udemy**has an extensive amount of resources to learn about cryptography and its implementation using various programming languages.**Cybrary**also provides a wide range of courses on Cryptography.

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