# Cryptography:

Cryptography is a technique by which we convert plaintext to ciphertext and ciphertext to plaintext. With the help of cryptography, we keep the message in secret code. Cryptography is used to protect information such as e-mail, messages, and protects credit card information.

Cryptography uses two methods:

**1.Encryptions:**In encryption, the plaintext is converted to ciphertext.

**2. Decryption:**In decryption, the ciphertext is converted to plaintext.

**For example,**A sent the message to B. And A wants that only B can read that message and no one else can read that message. If someone has read the message then he will not be able to understand that message. So we use cryptography as the message is sent in the form of ciphertext.

**Cryptography Terms:**

**Plaintext:**Any message user in plaintext can understand what is written in the message.

**Ciphertext:**

ciphertext contains a secret message in which an unauthorized user can read the message but cannot understand what is written in the message.

**Encryptions:**In encryption, the plaintext is converted to ciphertext.

**Decryption:**In decryption, the ciphertext is converted to plaintext.

**Cipher:**The algorithm for converting plaintext to ciphertext is called a cipher.

**Features of Cryptography:**

**Confidentiality**

**Integrity**

**Non-repudiation**

**Authentication**

**1. Confidentiality:**

Confidentiality means that only the sender and receiver can read the message. Like - A has sent a message to B. Apart from these two, no person can read that message, so as long as confidentiality remains, the credibility is gone. When an unauthorized person reaches that message.

**2. Integrity:**

Integrity means that the sender has sent a message to the receiver. So in the meantime, there should be no modification in that message, till then the integrity remains intact if anything changes in the message then the integrity is lost.

**3. Non-repudiation:**

In non-repudiation, it does not allow the gender to be denied after sending the message.

**4. Authentication:**

Authentication means that it authenticates the user's identity and confirms that the person sending the message is the same person, is there no other person.

**Types of Cryptography:**

**1.Symmetric Cryptography:**

Symmetric cryptography uses the same key, meaning the sender and receiver have the same key and that key is used to convert plaintext to encryption and ciphertext to decryption.

Symmetric cryptography is called a private key or secret key cryptography.

**2.Asymmetric Cryptography:**

Asymmetric cryptography uses two different types of keys, the first key is used to

**encrypt**data and the second key is used to**decrypt**the data.Asymmetric cryptography has a public key that everyone knows and another secret key that only the receiver knows.

Asymmetric cryptography is called public-key cryptography.

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