FUNDAMENTALS OF COMPUTER

Detailed explanation-1: -To decrypt, take the first letter of the ciphertext and the first letter of the key, and subtract their value (letters have a value equal to their position in the alphabet starting from 0). If the result is negative, add 26 (26=the number of letters in the alphabet), the result gives the rank of the plain letter.

Detailed explanation-2: -Ciphertext is encrypted text transformed from plaintext using an encryption algorithm. Ciphertext can’t be read until it has been converted into plaintext (decrypted) with a key. The decryption cipher is an algorithm that transforms the ciphertext back into plaintext.

Detailed explanation-3: -Decryption, which is the process of decoding an obscured message, is carried out by the message receiver. The security provided by encryption is directly tied to the type of cipher used to encrypt the data–the strength of the decryption keys required to return ciphertext to plaintext.

Detailed explanation-4: -Encryption is the process by which a readable message is converted to an unreadable form to prevent unauthorized parties from reading it. Decryption is the process of converting an encrypted message back to its original (readable) format. The original message is called the plaintext message.