What is Cryptography?


Cryptography is the practice and the study of techniques for securing communication and data in the presence of adversaries. Cryptography provides secure communication in the presence of malicious third parties known as adversaries.


Firstly a message is converted into numeric form and the numeric form is applied with a key called an encryption key and that encryption key is used in an encryption algorithm
so once the numeric message and the encryption key has been applied in an encryption algorithm, what we get is called a ciphertext.
The resulting ciphertext is sent over the network to the other side where the other person whose message is intended for will actually use a decryption key and use the ciphertext as a parameter of a decryption algorithm and when the person will get what we actually sent as a message and if some error had occurred then they’ll get an error.

Types of cryptography

  • Symmetric key cryptography : It is an encryption system where the sender and receiver of message use a single common key top encrypt an decrypt messages. symmetric key system are faster and simpler but the problem is that sender and receiver have to somehow exchange key in a secure manner. The most popular symmetric key cryptography system is Data Encryption System (DES).
  • Hash function : There is no usage of any key in this algorithm . A hash value with fixed length is calculated as per the plain text which make it impossible for contents of plain text to be recovered . Many operating systems use hash functions to encrypt passwords.
  • Asymmetric key cryptography : Under this system a pair of keys is used to encrypt and decrypt information. A public key is used for encryption and a private key is used for decryption . Public key and private key are different so, even if the public key is known by everyone the intended receiver can only decode it because he alone knows the private key.

Features of cryptography

  • Confidentiality : Information can only be accessed by the person for whom it is intended and no other person except him/her can access the information
  • Integrity : Information cannot be modified in storage or transition between sender and intended receiver without any addition to information being detected.
  • Non-repudiation : The creator/sender of information cannot deny his or her intention to send.
  • Authentication : The identities of sender and receiver are confirmed. As well as destination/origin of information is confirmed.
  • Unobstructed channel of communication : As the cryptographic channels do not involve any adversaries, the channel of communication only takes place between the sender and the receiver of the message . so, the receiver channel of communication is unobstructed and does not have a pass through a third party’s verification portal.


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