The section on public key cryptosystems discussed nonrepudiation of origin in the context of public key cryptosystems. Consider a secret key system (in which a shared key is used). Bob has a message that he claims came from Alice, and to prove it he shows both the cleartext message and the ciphertext message. The ciphertext corresponds to the plaintext enciphered under the secret key that Alice and Bob share. Explain why this does not satisfy the requirements of nonrepudiation of origin. How might you modify a classical cryptosystem to provide nonrepudiation?

Kyle, a receptionist for a building supply company, recently won an award for saving his company money on their phone system. after being presented with kyle's research, the company changed the way in which it made long-distance phone calls and cut their expenses in this area by 75 percent. the new system the kyle's company most likely adopted was wired communications switching stations voip hdtv

Write a function balancechemical to balance chemical reactions by solving a linear set of equations. the inputs arguments are: reagents: symbols of reagents in string row array products: symbols of products in string row array elements: elements in the reaction in string row array elcmpreag: elemental composition of reactants in two dimensional numeric array elcmpprdcts: elemental composition of prducts in two dimensional numeric array hint: the first part of the problem is setting up the set of linear equations that should be solve. the second part of the problem is to find the integers from the solution. one way to do this is to mulitiply the rational basis for the nullspace by increasing larger integers until both the left-and right-side integers exist. for example, for the reaction that involves reacting with to produce and : reagents=["ch4", "o2"]; products =["co2", "h2o"]; elements =["c","h", "o"] elcmpreag=[1,4,0;

This program should be a short piece of code that prints all of the positive integers from 1 to 100 as described more fully below. the program may contain multiple methods, and if using an oo language, should be contained within a single class or object. the program should be designed so that it begins execution when invoked through whichever mechanism is most common for the implementation language. â–ş print out all positive integers from 1 to 100, inclusive and in order. â–ş print messages to standard output, matching the sample output below. â–ş in the output, state whether the each integer is 'odd' or 'even' in the output. â–ş if the number is divisible by three, instead of stating that the number is odd or even, state that the number is 'divisible by three'. â–ş if the number is divisible by both two and three, instead of saying that the number is odd, even or divisible by three; state that the number is 'divisible by two and three'. â–ş design the logic of the loop to be as efficient as possible, using the minimal number of operations to perform the required logic. sample output the number '1' is odd. the number '2' is even. the number '3' is divisible by three. the number '6' is divisible by two and three.