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MBA IT, Mater in Science and Technology
Devry
Jul-1996 - Jul-2000
Professor
Devry University
Mar-2010 - Oct-2016
Choose two three-digit primes and an encryption exponent (3 or 17 may do nicely, or you mayhave to choose another one).a) Use these parameters to define an RSA cryptosystem.b) Take the last three digits of your banner ID and encrypt that number with the RSA systemdefined above.c)Find the corresponding decryption exponent and verify that everything worked.
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Page 1ECE597xx/Koren Sample Midterm.1.1ï›™2015 Koren UMassIsrael KorenUNIVERSITY OF MASSACHUSETTSDept. of Electrical & Computer EngineeringIntroduction to CryptographyECE 597XX/697XXSample Test QuestionsECE597xx/Koren Sample Midterm.1.2ï›™2015 Koren UMass1. Substitution ciphers may be subject to frequency attacks. To reducethe effectiveness of such attacks groups of k (k>1) letters can besubstituted individually, i.e., the plaintext is partitioned into groups of kletters each and every group is substituted separately (Hill’s cipher).(a) What would be the key size for k=2? Write an expression for the keysize as a function of k (k>1) and compare it to the key size for k=1.(b) The key size can be reduced by using a common transformation for allgroups of k letters. For example, for k=2 the matrix M below can beused to substitute the pair x1x2by y1y2.The calculation is done mod 26, e.g.,Encrypt the plaintext SNOW using the matrixï£ï£«=dcbaMï£ï£«ï£·ï£·ï£¸ï£¶ï£¬ï£¬ï£ï£«=ï£ï£«2121xxdcbayy26mod211xbxayâ‹…+â‹…=ï£ï£«=2134M
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