asp.net barcode Designing for High Accessibility and Low Bandwidth in .NET

Encoder QR in .NET Designing for High Accessibility and Low Bandwidth

8.2 Summary ......................................................... 108

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n the previous chapter, we dealt with virtualized abstractions, crystalline concepts floating in a sea of imagination. Now, we will go down to the very real floor of the carrier systems that make the abstractions possible and discover that some of the floor s supports may themselves be virtualized. Boundaries between carrier and customer, between telephone companies and ISPs, are blurring. As the cartoon character Pogo says, we have met the enemy and they are us. Telephone competition began with alternative long distance providers, then with competitive local exchange carriers. Both IXCs and CLECs began as traditional telephone companies. Now, however, telephony is a service offered by providers that previously offered only IP services, cable television, Much of this book focuses on WANs from the customer rather than the provider standpoint. The emphasis of this chapter, however, is on the provider, or provider-like organizations such as large hosting centers.

While RSA is used in most Web browsers in the SSL protocol, there are other products (such as PGP) and many government systems that base public key operations on discrete logarithms. These come in a number of flavors, some using normal arithmetic, while others use mathematical structures called elliptic curves. I ll explain the normal case, as the elliptic variants use essentially the same idea but the implementation is more complex. A primitive root modulo p is a number whose powers generate all the nonzero numbers mod p; for example, when working modulo 7, we find that 5 2 = 25, which reduces to 4 (modulo 7), then we can compute 5 3 as 5 2 x 5 or 4 x 5, which is 20, which reduces to 6 (modulo 7), and so on, as shown in Figure 5.18. Thus, 5 is a primitive root modulo 7. This means that given any y, we can always solve the equation y = 5 x (mod 7); x is then called the discrete logarithm of y modulo 7. Small examples like this can be solved by inspection, but for a large random prime number p, we do not know how to do this computation. So the mapping f : x g x (mod p) is a one-way function, with the additional properties that f(x + y) = f (x) f (y) and

In the homogeneous case, we let t = v - u and get from Eqs. (2.39) and (2.40) time-independent transition rates qij = qij(t),Vi, j E S, such that simpler versions of the Kolmogorov s forward differential equation for homogeneous CTMCs result: (2.44) Instead of the forward Eq. (2.43), we can equivalently derive and use the Kolmogorov s backward equation for further computations, both in the homogeneous and non-homogeneous cases, by letting w -+ u in Eq. (2.42) and taking limat+o to get:

Holding employees accountable in their jobs is a challenging aspect of any manager s job. Consider the following questions that address topics covered in this chapter: