What would be the length of the header as a function of n-k

Assignment Help Computer Engineering

Reference no: EM132139008

Suppose Alice shares a secret block cipher key, K_AB with Bob, and a different secret block cipher key, K_AC with Charlie.

Describe a method for Alice to encrypt an m-block message such that it can only be decrypted with the cooperation of both Bob and Charlie.

The cipher text should only be a constant size greater than m blocks.

You may assume that Bob and Charlie have a pre-established secret channel on which to communicate.

Now, suppose Alice shares a block cipher key, K_AB with Bob, a block cipher key K_AC with Charlie, and a block cipher key K_AD with David.

Describe a method for Alice to encrypt an m-block message such that any two of Bob, Charlie, and David can decrypt (for example, Bob and Charlie can decrypt), but none of them can decrypt the message themselves.

Again, the cipher text should only be a constant size greater than m blocks. How does your solution from part (b) scale as we increase the number of recipients?

In other words, suppose Alice has a secret key with each of n recipients and wants to encrypt so that any k out of n recipients can decrypt, but any k-1 cannot.

What would be the length of the header as a function of n and k?

Reference no: EM132139008

Questions Cloud

How many favor only adding more highways : How many favor only adding more highways? How many favor a combination of an expanded bus system and rail?

How many comparisons will insertion sort perform : How many comparisons will insertion sort perform when it is executing the pass that moves the element at index n-1 into position?

What is organisational communication : The organisation as a whole and formal communication channels - establishing and maintaining formal and informal channels of communication downward

Propose a plan for performance improvement : Sunshine Health Corporation is seeking to improve overall connectivity across their corporate campus near the Hawaii Kai Marina, Honolulu, Hawaii.

What would be the length of the header as a function of n-k : Describe a method for Alice to encrypt an m-block message such that any two of Bob, Charlie, and David can decrypt.

How many bits of entropy does this string contain : Suppose you have a 50-bit string that contains exactly 37 ones at random positions. How many bits of entropy does this string contain?

Estimate how long the same algorithm running on the same : Suppose that an algorithm takes 30 seconds for an input of 224 elements (with some particular, but unspecified speed in instructions per second).

How would the business strategy affect your approach : Suppose you are the analyst charged with developing a new system to help senior managers make better strategic decisions.

Critique or defend the use of the application : Explain the advantages and disadvantages of each. If you locate such a guide online, please make sure you give credit where credit is due.

User Account

All Pages