Tham khảo tài liệu 'hacker professional ebook part 163', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | and broken for real yet continued use will endanger all messages so protected. Thus it is a very reasonable policy to not adopt a widely-used cipher and to change ciphers periodically. Cryptology The field of study which generally includes steganography cryptography and cryptanalysis. Current The measure of electron flow in amperes. Current is analogous to the amount of water flow as opposed to pressure or voltage. A flowing electrical current will create a magnetic field around the conductor. A changing electrical current may create an electromagnetic field. dB decibel. DC Direct Current Electrical power which flows in one direction more or less constantly. As opposed to AC. Most electronic devices require DC -- at least internally -- for proper operation so a substantial part of modern design is the power supply which converts 120 VAC wall power into 12 VDC 5 VDC and or 3 VDC as needed by the circuit and active devices. Debug The interactive analytical process of correcting the design of a complex system. A normal part of the development process although when bugs are not caught during development they can remain in production systems. Contrary to naive expectations a complex system almost never performs as desired when first realized. Both hardware and software system design environments generally deal with systems which are not working. When a system really works the design and development process is generally over. Debugging involves identifying problems analyzing the source of those problems then changing the construction to fix the problem. Hopefully the fix will not itself create new problems. This form of interactive analysis can be especially difficult because the realized design may not actually be what is described in the schematics flow-charts or other working documents To some extent the real system is unknown. When a system has many problems the problems tend to interact which can make the identification of a particular cause very difficult. This can
