Ipnfxpsl $4

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]** *p* and *q*) in each case:

a) *p* and *q* terribly:

*N *= 37649606755989309660848896543522520184860442468875173906157

*e* = 3

b) *p*
and *q*, but failed yet again (though
not as obviously):

*N*=2073460713594865259966662742102733483131915732787396625056411028069852706118260281187468578469941017601

*e*=3

c) *d* by hacking into her private computer:

*N*=49292648137019202972571737254366871219319612585889780030657

*e*=3

*d*=39434118509615362378057389803136588904534865635739948641181

4. **[EXTRA 0.25
points]** Factor N=188198812920607963838697239461650439807163563379417382700763356422988859715234665485319060606504743045317388011303396716199692321205734031879550656996221305168759307650257059