Encryption has a remarkably long and varied history. spies have been using it to convey secret messages ever since there were secret messages to convey. one powerful method of encryption uses random digits. two documents are prepared with the same random sequence of numbers. the spy is sent out with one and the spy master retains the other. the digits are used as follows. suppose that the word to be encrypted is spy and the random digits are 352. then s becomes v (three letters after s), p becomes u (five letters after p), and y becomes a (two letters after y, restarting at a after z). the spy would encrypt a message and then destroy the document used to encrypt it. this is an early example of a. a hashing algorithm. b. asymmetric key encryption. c. symmetric key encryption. d. public key encryption.

Through the process of sedimentation,sediment is turned back to rock to form sedimentation.the process of sedimentation is: > deposition-where fragments were deposited into the river or sea under gravity or travelling agent such as wind or water. > sedimentation-the fragments deposited in the river sedimented and accumulate> compaction-the layers of fragments deposited undergoes compaction due to the weight if the upper layers> cementation-chemical substance of the fragments such as cement dissolved into the water and cement the other fragments together to form sedimentary rock.thus,cementation and compaction are the process.on the other hand, transformation only occur when a rock under goes metamorphism(compaction or extreme heat).while recrystillization occurs when a rock is melted and cooled down,which also requires metamorphism to take place.hope it !

Answerantispyware;