công ty, sở hữu bí mật hoặc sử dụng nội bộ. Mỗi chính sách cho một phân loại các thông tin mô tả nó như thế nào cần được bảo vệ, người có thể truy cập vào nó, người có thẩm quyền để phát hành nó và làm thế nào nó phải được tiêu huỷ. | SY0 - 201 is still in wide use. It remains very effective because of the nature of what it is protecting a temporary automatically generated secret key that is good only for a single communication session. ElGamal ElGamal can be used for both encryption and digital signatures. Taher ElGamal designed the system in the early 1980s. This system was never patented and is free for use. It is used as the . government standard for digital signatures. The system is based upon the difficulty of calculating discrete logarithms in a finite field. Three numbers are needed to generate a key pair. User 1 chooses a prime P and two random numbers F and D. F and D should both be less than P. ECC Elliptic curve cryptography ECC works on the basis of elliptic curves. An elliptic curve is a simple function that is drawn as a gently looping curve on the X Y plane. They are defined by this equation y2 x3 ax2 b Elliptic curves work because they have a special property you can add two points on the curve together and get a third point on the curve. For cryptography the elliptic curve works as a public key algorithm. Users agree on an elliptic curve and a fixed curve point. This information is not a shared secret and these points can be made public without compromising the security of the system. User 1 then chooses a secret random number K1 and computes a public key based upon a point on the curve P1 K1 F User 2 performs the same function and generates P2. Now user 1 can send user 2 a message by generating a shared secret S K1 P2 User 2 can generate the same shared secret independently S K2 P1 This is true because K1 P2 K1 K2 F K1 K2 F K2 K1 F K2 P1 The security of elliptic curve systems has been questioned mostly because of lack of analysis. However all public key systems rely on the difficulty of certain math problems. Leading the way in IT testing and certification tools - 40 - SY0 - 201 It would take a breakthrough in math for any of the mentioned systems to be .
