Ebook giới thiệu các công cụ và đồ nghề cần thiết cho việc Hack-Security. Ebook gồm có 1177 bài viết trong 28 chủ đề chính Phần 16: 10 part gồm Tools and toys for Hacking. | various stages of processing. Although a clock signal is digital the source of the repetitive signal is almost always an analog circuit. In an analog system we might produce a known delay by slowly charging a capacitor and measuring the voltage across it continuously until the voltage reaches the desired level. A big problem with this is that the circuit becomes increasingly susceptible to noise at the end of the interval. In a digital system we create a delay by simply counting clock cycles. Since all external operations are digital noise effects are virtually eliminated and we can easily create accurate delays which are as long as the count in any counter we can build. Closed An operation on a set which produces only elements in that set. Code Symbols or values which stand for symbols values sequences or even operations as in computer opcodes . As opposed to a cipher which operates only on individual characters or bits classically codes also represent words phrases and entire sentences. One application was to decrease the cost of telegraph messages. In modern usage a code is often simply a correspondence between information such as character symbols and values such as the ASCII code or Base-64 although computer opcodes do have independent meanings and variable lengths. Coding is a very basic part of modern computation and generally implies no secrecy or information hiding. Some codes are secret codes however and then the transformation between the information and the coding is kept secret. Also see cryptography and substitution. Codebook Literally the listing or book of code transformations. More generally any collection of such transformations. Classically letters common words and useful phrases were numbered in a codebook messages transformed into those numbers were coded messages. Also see nomenclator. A codebook style cipher refers to a block cipher. Codebook Attack A form of attack in which The Opponent simply tries to build or collect a codebook of all the
