CS 772

Assignment #1

Due Midnight, Thursday Sept. 25, 2008

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( I )

file1.cipher is the result of encrypting an English text file using a generalized Caesar cipher.

Use the statistical frequency analysis to reveal the corresponding English text and the used Caesar cipher shift.

( II )

file2.cipher is the result of encrypting an English text file using the simple XOR encyption .

The encryption key used is a lower case word of length <= 4.

You are required to reveal the corresponding English text and the used encryption key.

( III )

Use openssl to:

1. Create a public/private key pair of your own, call the file containing your public key:  <login>PublicKey.pem

<login> is your login name (e.g., wahabPublicKey.pem).

2. Choose a password and store it in a file called: symPasswd.txt,

encrypt this file  using cs772 PublicKey,

encode the result to base-64 and store it in a file called symPasswd.base64

3. Let A1.zip be the zip file containing all relevant files of your solution to  parts I. and II.

For example, if you like to submit files: f1 f2 f3 under  the current directory you may use the command:  

% zip   A1.zip  f1 f2 f3

4. Sign the message digest of  A1.zip  using  your private key,

encode the result  to base-64 and store it in a file called: A1ZipMdSignature.base64

5. Encrypt A1.zip using the password stored in symPasswd.txt and let A1Zip.base64 be the encrypted base64 encoded file.

6. Create one file called   <login>A1Files.zip that contains:

1. <login>PublicKey.pem

2. symPasswd.base64

3. A1Zip.base64

4. A1ZipMdSignature.base64

For example:

% zip wahabA1Files.zip wahabPublicKey.pem symPasswd.base64 A1Zip.base64 A1ZipMdSignature.base64

7. Finally, submit <login>A1Files.zip to cs772 under the directory Assignment  #1.

Important Note:

Please use the names listed above since a shell script is used to grade the assignment & it is case and name sensitive.