mw1.txt

一个简单的移位密码算法程序

                        Telecommunications and Information Superhighway
  Telecommunications allows people around the world tocontact one another, to access information instantly, and tocommunicate from remote areas. Telecommunications usually involves a sender of information and one or more recipients linked by a technology, such as a telephone system, that transmits information from one placeto another.Telecommunications devices convert different types of information, such as sound and video, into electronic signals. The signals can then be transmitted by means of media such as telephone wires or radio waves. When a signal reaches its destination, thedevice on the receiving end converts the electronic signal back into an understandable message, such as sound over a telephone, moving images on a television, or words and pictures on a computer screen.Telecommunications enables people to send and receive personal messages across town, between countries, and to and from outer space. It also provides the keymedium for news, data, information and entertainment.
  Telecommunications messages can be sent in a variety of ways andby a wide range of devices. The messages can be sent from one sender to a single receiver (point-to-point) or from one sender to many receivers (point-to-multipoint). Personal communications, such as a telephone conversation between two people or a facsimile (fax) message, usually involve point-to-point transmission. Point-to-multipoint telecommunications, often called broadcasts, provide the basis for commercial radio and television programming.