With secret key cryptography, a single key is used for both encryption and decryption. As shown in Figure the sender uses the key (or some set of rules) to encrypt the plain text and sends the ciphertext to the receiver. The receiver applies the same key (or ruleset) to decrypt the message and recover the plain text.
Proofreading means examining your text carefully to find and correct typographical errors and mistakes in grammar, style, and spelling. Usually, for those who do not have time, they hire a professional proofreaders to help them do it. Before You Proofread: Set your text aside for a while (15 minutes, a day, a week) between writing and proofing. Some distance from the text will help you see mistakes more easily.
Which see â used after a term or phrase that should be looked up elsewhere in the current document or book. Quod erat demonstrandum (Q.E.D.). That which was to be demonstrated â often written (abbreviated) at the bottom of a mathematical proof.