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What is Cryptography?

Introduction Of Cryptography

Cryptography is a means for implementing some security mechanisms. The term of 'Cryptography' is derived from two Greek words, namely crypto and graphy. In greek language crypto means secret and graphy means writing.

  • Cryptography is the science of secret writing that provides various techniques to protect information that is an unreadable format. This unreadable format only by the intended recipients.

  • It is the science of converting a message into a code from that hides the information contained in the message. We encrypt a message before its transmission so that an eavesdropped may not get the information contained in the message.

   Plaintext : The original unencrypted message is called plaintext

   Ciphertext : The encryption message is called ciphertext.

# Cryptography technique and protocols:

Cryptography techniques and protocols are used in a wide range of application such as secure electronic transactions, se audio/video broadcasting and se video conferences.

  • In secure electronic transactions, cryptography techniques are used to protect E-mail messages, Credit-card information and other sensitive information.

  • In secure audio/video broadcasting the service provider sends the requested audio/video data to subscribers in a secure way. Only the authorized subscribers are allowed to views the multimedia data.

  • It is used in video conferences to allow multi-party communication, where one user speaks and the remaining users view the communicated data is a secure way.

  • These secure application are heavily dependent on various cryptography services namely confidentiality, authentication and data integrity.

Based on these cryptography servic, the cryptography technique and protocols are classified into 4-main regions and are as follows :

  1. Symmetric Encryption.

  2. Asymmetric Encryption.

  3. Data integrity Techniques.

  4. Authentication Protocols.

1.) Symmetric Encryption : Symmetric encryption is an application technique is which identical cryptography key is used for both encrypting and decrypting the information. Tnis key in practice must be secret between the sender and the receiver to maintain the secrecy of the information.

2.) Asymmetric Encryption : Asymmetric encryption is an encryption technique where two keys are used as a pair. Among these two keys, one key is used for encryption and the other key is used for decryption of information. In the pair of keys, if the sender uses any one key to encrypt a message, the receiver should use another key to decrypt the message.

3.) Data integrity Techniques : These techniques are used to protect information from alteration during the transmission. Data integrity techniques assure to maintain the accuracy and consistency of information over its entire life cycle.

4.) Authentication Protocols : These are designed based on the use of cryptographic techniques to authenticate the identity of the sender. These protocols allow only the valid users to access the resources located on a server.

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