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TD811 ==Npefso Jogpsnbujpo Qspupdpmt
Cptupo Vojwfstjuz
Assigned:
DUE: November 25 at the beginning of class.
In each case, to get full credit you must a) show your work,
mentioning the techniques used for decryption; b) include any programs you use
for the decoding. You might want to make
use of Maple or Mathematica, available on engc, for
large-integer arithmetic.
1.
[40 points]
a) Agents have determined that the following English message was encrypted with a substitution cipher. Please decode it:
foxpxefmxqqrhxjrqxpdlbxbuqiphryihxpxaxdinoxafoxsxztxphforpbdlpfxpfqraxtxwfwlazluflbxdinoxauqiphfoxfxdopivuxqzlumrzoryxtxrapxbipdtrqqdrpzlublif
b) The following strange cipher was found on an
e-mail signature sent to you by a friend.
What does it say?
KCCPKBGUFDPHQTYAVINRRTMVGRKDNBVFDETDGILTXRGUDDKOTFMBPVGEGLTGCKQRACQCWDNAWCRXIZAKFTLEWRPTYCQKYVXCHKFTPONCQQRHJVAJUWETMCMSPKQDYHJVDAHCTRLSVSKCGCZQQDZXGSFRLSWCWSJTBHAFSIASPRJAHKJRJUMVGKMITZHFPDISPZLVLGWTFPLKKEBDPGCEBSHCTJRWXBAFSPEZQNRWXCVYCGAONWDDKACKAWBBIKFTIOVKCGGHJVLNHIFFSQESVYCLACNVRWBBIREPBBVFEXOSCDYGZWPFDTKFQIYCWHJVLNHIQIBTKHJVNPIST
2.
[15
points]
08864 00235 20699 08186 16629 01277 16675
19828 12791
Alice's jealous ex-boyfriend, Oscar, has hired you at significant expense to
find out the location of the meeting.
Decrypt the message.
3. [45
points]
a)
N = 37649606755989309660848896543522520184860442468875173906157
e = 3
b)
N=2073460713594865259966662742102733483131915732787396625056411028069852706118260281187468578469941017601
e=3
c)
N=49292648137019202972571737254366871219319612585889780030657
e=3
d=39434118509615362378057389803136588904534865635739948641181
4. [EXTRA 0.25
points] Factor N=188198812920607963838697239461650439807163563379417382700763356422988859715234665485319060606504743045317388011303396716199692321205734031879550656996221305168759307650257059