ccna after 10th

ccna after 10th.7.1.1.4 Data confidentialityData confidentiality protects privacy by making it possible for only the recipient to read the message. Encryption is the process of scrambling data so that unauthorized communicating parties cannot read it. When encryption is enabled, readable data is called plaintext (or cleartext), while encrypted data is called ciphertext. Plaintext readable messages are converted into ciphertext, which is an unreadable, disguised message. Decryption is the opposite process. Encrypting and decrypting a message requires188 Chapter 7 Cryptographic Systemsa key. The key is the link between the plaintext and the ciphertext.Throughout history, various encryption algorithms and methods have been used. Julius Caesar is said to have encrypted messages by putting two sets of alphabetsone after the other and then shifting one of them by a certain number of positions. The number of shifted positions acted as a key. He used this key to convert the plaintextinto cipher text, and only his generals knew this key and knew how to decrypt the message. This method is now known as the Caesar cipher.Hashing is another method of ensuring the confidentiality of data. A hash function converts a string into a shorter, fixed-length value or key to represent the original string. The difference between hashing and encryption is how the data is stored. With encrypted text, the data can be decrypted out of the way with a key. With a hash function, when the data is entered and transformed by the hash function, the plaintext is gone. The hashed data is only used for comparison. For example, when a user enters a password, the password is hashed and then compared to the stored hash value. If the user forgets the password, the password must be reset since it is not possible to decrypt the stored values.The purpose of encryption and hashing is to ensure confidentiality so that only authorized entities can read the message.7.1.2 Cryptography