Computer Security and Cryptography

2.4 EXAMPLES OF CRIBBING

Example 2.2

The ciphertext is of length n = 446:

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                         cipherEx2.2
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m c g trfttsaocehyhrsayohalolcintTm cgt s ilcdlCtf aunods ng
c ea e ts enuuc nnrcog e eam otsliy, ukrsima meuc aUotxgits
nmotr tad inw e wafscfuus ttihdea dri d.yptlo in 2rtsatmts
s tipmCvhc ecepnhors oldlwc iin iids,irornsraaeow acT tcg
cuemar blte nos ornoaBrstua p eosrsiro skdins eerfn ,nad.Cee
ae mp onle ,ueouov wf4 e teuiy.ceer Seiimfdi.l ige bbfl ehau
ndgaoecyi nypseuodii hhtddorn e nsmone locsehpser c enteiio
i pml aykaoehbd roasitbsds
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We assume it is known that plainEx2.2 is from a 1982 UCSB Computer Science Department brochure. It is therefore reasonable to assume computer science, Computer science, or Computer Science as possible cribs.

2.4.1 Testing Possible Widths

Table 2.10 lists the subcribs of computer science for widths 5 ≤ N ≤ 9.

Table 2.11 contains the output of the program Search1, which lists all subcribs of computer science that do not occur in y:

Search1
Input:	Interval of widths N0 ≤ N ≤ N1, (w, y)
Output:	All subcribs of w which do not occur in y

TABLE 2.10 The Subcribs of computer science for 5 ≤ N ≤ 9

TABLE 2.11 Output of Search1 for computer science width 5 ≤ N ≤ 9

N	Subcribs ...