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Scott, MIT Graduate
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Experience:  MIT Graduate (Math, Programming, Science, and Music)
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1) A 2,000-bit message is used to generate a 256-bit hash.

Customer Question

1) A 2,000-bit message is used to generate a 256-bit hash. One the average, how many other messages could be expected to generate the same hash value? What does this tell us about the length of a hash as compared to the length of the message?

2) Using the English alphabet (i.e., mod 26 arithmetic) let plaintext = {p1, p2,… , pn} and corresponding ciphertext = {c1, c2,… , cn}. Suppose the encryption function is ci = pi + 5 (mod 26). If you receive the ciphertext message RNQJDHDWZX, decrypt to recover the plaintext. What is the decryption function, and the recovered plaintext? What type of cipher is this? What are some weaknesses of this cipher?

3. Substantiate or refute the following statement: The cryptographic basis of the Enigma machine is the use of a trapdoor function.

4. Consider the following plaintext message: THE BOILING POINT OF WATER IS 212 DEGREES FAHRENHEIT.
a. If this message is sent unencrypted and successfully received, what is its entropy?
b. If this message is encrypted with DES using a random 56-bit key, what is the encrypted message’s entropy?
c. If this message is encrypted with 3DES (using an optimal set of keys) what is the encrypted message’s entropy?
Submitted: 3 years ago.
Category: Homework
Expert:  Angela--Mod replied 3 years ago.

Hello, I'm a moderator for this topic. I've been working hard to find a professional to assist you right away, but sometimes finding the right professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. Please let me know and I will assist further. Thank you!



Customer: replied 3 years ago.

How much longer?

Expert:  Angela--Mod replied 3 years ago.

Thank you for your patience while we continue to search for a professional to assist you.

Unfortuntely, we cannot guarantee or predict response time, but I have marked your question high priority and you’ll receive an email notification as soon as you have a new reply.
Customer: replied 3 years ago.

I can only wait till tomorrow evening. Hopefully my money will be worth the wait.


Customer: replied 3 years ago.

If you can't guarantee anything, than why have this website.


Besides, I have already answered the questions. So lets go ahead and cancel my request, unless you have the answer by 4:00pm today. If not, forget it and delete or remove my account from your sites.

P.S. The questions are on IT Cryptography and not in Business Systems.



Customer: replied 3 years ago.

Times up...please cancel! You all are not worth coming back 2!

Bye Bye

Expert:  Mr. Gregory White replied 3 years ago.
Hello, my name is Greg.

The moderator let me know that you might be needing assistance but I see that it might be past your deadline.

I am sorry that we were unable to help on this prompt. Many experts have reviewed your question so far, but no one at this time has felt comfortable trying to help. The question may be just to difficult or not informative enough or priced to low.

If your question is still needed, fell free to reply back and let me know. You can also request me by putting "For Greg" at the front of your post so it is forwarded to me right away.

You are a valued customer and I hope you will consider us for your future needs.

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