{"id":431425,"date":"2018-03-24T02:24:46","date_gmt":"2018-03-24T02:24:46","guid":{"rendered":"https:\/\/essaypaper.org\/security\/"},"modified":"2018-10-24T09:17:46","modified_gmt":"2018-10-24T09:17:46","slug":"security-4","status":"publish","type":"post","link":"https:\/\/www.benedictsol.com\/blogs\/security-4\/","title":{"rendered":"security"},"content":{"rendered":"\n

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Assignment #1<\/span><\/u><\/strong><\/p>\n

Security in Computing COSC2536\/2537<\/span><\/h1>\n

 <\/span><\/span><\/u><\/strong><\/p>\n

Q1<\/span><\/u><\/strong><\/p>\n

(a)<\/span><\/u><\/strong> Decrypt the ciphertext <\/span><\/p>\n

 <\/span><\/p>\n

IAUTMOCSMNIMREBOTNELSTRHEREOAEVMWIH<\/span><\/strong><\/p>\n

TSEEATMAEOHWHSYCEELTTEOHMUOUFEHTRFT<\/span><\/h3>\n

 <\/span><\/p>\n

This message was encrypted with a double transposition (of the type  <\/span>discussed in the lecture and tute) using a matrix of 7 rows and 10 columns. Hint:<\/em>  <\/span>The first word is “there.”<\/span><\/p>\n

(Marks 1.5)<\/span><\/strong><\/p>\n

 <\/span><\/strong><\/p>\n

(b)<\/span><\/u><\/strong> Find the plaintext and the key, given the cipher-text<\/span><\/span><\/p>\n


<\/span>CSYEVIXIVQMREXIH.<\/span><\/strong><\/span><\/p>\n

(Marks 1)<\/span><\/strong><\/p>\n

 <\/span><\/strong><\/p>\n

(c)<\/span><\/u><\/strong> Decrypt the following message that was encrypted using a simple substitution cipher:<\/span><\/span>
<\/span>GBSXUCGSZQGKGSQPKQKGLSKASPCGBGBKGUKGCEUKUZKGGBSQEICA<\/span><\/strong><\/span>
<\/span><\/strong>CGKGCEUERWKLKUPKQQGCIICUAEUVSHqKGCEUPCGBCGQOEVSHUNSU<\/span><\/strong><\/span>
<\/span><\/strong>GKUZCGQSNLSHEHIEEDCUOGEPKHZGBSNKCUGSUKUASERLSKASCUGB<\/span><\/strong><\/span>
<\/span><\/strong>SLKACRCACUZSSZEUSBEXHKRGSHWKLKUSQSKCHQTXKZHEUQBKZAEN<\/span><\/strong><\/span>
<\/span><\/strong>NSUASZFENFCUOCUEKBXGBSWKLKUSQSKNFKQQKZEHGEGBSXUCGSZQ<\/span><\/strong><\/span>
<\/span><\/strong>GKGSQKUZBCQAEIISKOXSZSICVSHSZGEGBSQSAHSGKHMERQGKGSKR<\/span><\/strong><\/span>
<\/span><\/strong>EHNKIHSLIMGEKHSASUGKNSHCAKUNSQQKOSPBCISGBCqHSLIMQGKG<\/span><\/strong><\/span>
<\/span><\/strong>SZGBKGCGQSSNSZXQSISQQGEAEUGCUXSGBSSJCqGCUOZCLIENKGCA<\/span><\/strong><\/span>
<\/span><\/strong>USOEGCKGCEUqCGAEUGKCUSZUEGBHSKGEHBCUGERPKHEHKHNSZKGGKAD<\/span><\/strong><\/span><\/p>\n

(Marks 2)<\/span><\/strong><\/p>\n

 <\/span><\/p>\n

Q2 <\/span><\/u><\/strong>Using the letter encodings in Table I, the following two cipher-text messages were encrypted with the same one-time pad: <\/span><\/p>\n

 <\/span><\/p>\n

KHHLTK<\/span><\/strong> and KTHLLE<\/strong><\/span><\/p>\n

 <\/span><\/strong><\/p>\n

Find all possible plaintexts for each message and the corresponding one-time pad.<\/span><\/p>\n

 <\/span><\/p>\n

Table I Abbreviated Alphabet<\/span><\/h2>\n

<\/p>\n

<\/span><\/p>\n

(Marks 3)<\/span><\/strong><\/p>\n

 <\/span><\/p>\n

 <\/span><\/p>\n

Q3  <\/span><\/span><\/u><\/strong> <\/span><\/span><\/em>Bob is a receiver and Alice is a sender. Bob generates public and private keys using RSA encryption algorithm and sends the public key to Alice. Alice has a message M<\/span><\/em>=8596<\/span><\/strong> to send.  <\/span>Bob uses parameter p<\/span><\/em>=89<\/span><\/strong> and q<\/span><\/em>=191<\/span><\/strong>, and chooses a small public key parameter e<\/span><\/em>.  <\/span><\/strong>What are the values of suitable public and private keys?  <\/span><\/strong>How would Alice encrypt message M<\/span><\/em>=8596<\/span><\/strong>? How would Bob decrypt the encrypted message C<\/span><\/em><\/strong> with the private key?<\/span><\/p>\n

(Marks 2.5)<\/span><\/strong><\/p>\n

 <\/span><\/p>\n

Q4 <\/span><\/strong>Alice has a message M<\/span><\/em>=37<\/span><\/strong> to send to Bob securely using ElGamal encryption algorithm. Bob chooses p<\/span><\/em>=8081<\/span><\/strong>, g<\/span><\/strong><\/em>=2849<\/span><\/strong>, x<\/span><\/strong><\/em>=53<\/span><\/strong>. Alice chooses r<\/span><\/em>=78<\/span><\/strong>. Show the encryption and decryption steps.<\/span><\/p>\n

(Marks 2.5)<\/span><\/strong><\/p>\n

 <\/span><\/p>\n

Q5 <\/span><\/strong>Alice has a message M<\/span><\/em>=186<\/span><\/strong> to send to Bob securely using Paillier encryption algorithm. Bob chooses p<\/span><\/em>=11<\/span><\/strong>, q<\/span><\/strong><\/em>=17<\/span><\/strong>,<\/em>and selects an integer g<\/span><\/strong> <\/em>=188<\/span><\/strong>. Alice selects a random number r<\/span><\/em>=97<\/span><\/strong>. Show the encryption and decryption steps.<\/span><\/p>\n

(Marks 2.5)<\/span><\/strong><\/p>\n

 <\/span><\/span><\/u><\/strong><\/p>\n

 <\/span><\/em><\/strong><\/p>\n

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The post security appeared first on Custom Essay Papers.<\/p>\n","protected":false},"excerpt":{"rendered":"

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