Encryption & Decryption

This lab assignment aims to employ tools and techniques learnt in the course to tackle the challenge of data decryption using investigative thinking. Participation in exploratory study will aid in the development of a critical approach and the analytical evaluation of the information displayed in coded visual form. When the company purchases the first available public key based app for data encryption / decryption management, it would be useful for security reasons to engage in regular practical experiential activity on elaboration new IT defense strategies about development optical recognition based software to cover needs for graphical decryption initiatives, as first suggested by Symantec (2010). An organization, presumably located in New York, got suspicious of actions of one of their employee’s actions. When he was notified of immediate termination out of organizational staff, he sent one email letter without any notice on subject, but it contained an image. It included zip file with instructions on encrypted data analysis. Company’s experts on investigation have been trying to figure out what exactly has been coded in this image. They are to exhibit their analytical and critical thinking skills to discover potential threat that may be encrypted in this image. Based on having info that the destination email address was traced to an Eastern European country, they may drop the assumption that this employee now works for their competitors, and that he moved to the East. In fact, it is difficult to find out if it is true, however, based on the hidden information that is included in this image; it is possible to decrypt the information encrypted in this file. To achieve this goal, investigators should follow the specific hints, based on experience of work with encryptions from the past learning experiences. Practically, keys for encryptions should be found in the image as keys / clues: numbers, words, graphics, etc. Latin letters can be treated in possible variants of misspell, based on parallels to foreign alphabet letters, words, and word-combinations. Phrases may be checked as well, including mechanisms and techniques of transliteration. Practically, analysis of visual elements of texture, composition, and layout of elements on the image may help to justify the significance of structural significance of all elements included into the picture.


The image exhibits the region of New York, the USA. This is proved by location of skyscrapers, high traffic, and exemplary inscription of the local U.S. number on one of the trucks that has been moving along the road, despite of red traffic lights are turned on to let cars stop (the number is to show the local ad to promote “Access-A-Ride” services: 1-877-337-2017). Logically, the last four digits of this number portray the current year, the period of time when cooperation with the employee was terminated. The number of the car that is moving the next after the truck with the ad is: 7832. When comparing both inscriptions one to another, it will turn out that 78 is the reverse variant to 87 that appears in the number 1-877-337-2017, and 32 is the reverse variant of 33 that appears in the same number. When taking a close look at skyscrapers, they contain visible inscription: “50WEST”. This inscription appears on two neighbouring corners of the building, and it can be reversely read as “SOUTHWEST”. The sign on the sidewalk states: “Stop here on red signal”. In the context of the visible encryption, it figuratively means that “it is banned move to the Southwest”. However, the row of cars does not follow traffic regulations, as marked to stop at red lights. However, the last car that is not visible in full in this image, as its visual representation is cut from the view in complete, shows two red lights as mirrored in the glass of its back door. Two red lights are reflected as the bleak in the mirror, so reversely they exhibit the need to move in the opposite direction to the East, rather than to the Southwest. To prove this point, image includes three inscriptions for traffic regulations: “ONE WAY”. In reality, “one way” means to move to the Southwest, while in reverse back mirror of the car in the row, the inscription “one way” is exhibited to prove the need for the opposite direction to move to the East. Opposite directions of “one way” in this image may reflect the employee’s intention to work for another company, as he can make a threat to his former employer on disclosure privacy issues or revealing secret confidential data, related to corporate policy or other activities that may bring harm to company’s reputation. The employee in such case may be driven by financial interest as well. The image he sent to his former employer proves the point that he stays still interested in cooperation with this company or expects to cover his need for taking part in some important decisions. The employees rationale justified benefit may be the clear sign of his progress on making a scheme on revenge plan to the organization, with which he cooperated before. Based on the formal organization of image symbols and clues, the inscription of “50WEST” may figuratively mean “SOUTHWEST”; but on the other hand, one of the walls of the exhibited skyscraper that appears on this image includes inscription of “50”, as the rest of the contextual content is hidden by other staffs on image. In this relation, playing with words in this inscription, we may exclude “SO” or “50”, and then exclude “WEST”, and then we will get the geographical name of UTAH, the state located in the Southwest of the USA. Supposedly, the meaning of this inscription is figurative, and it may show the correct direction. In addition, symbolically, ban to moving to the Southwest may figuratively mean the ban to decrypt the secret message hidden in this image. So, when correlate the distance between Utah and New York, we may discover the clue to the riddle.

Geographical map of the USA exhibits location of states. For instance, as related to the presented case, the relationship between New York and Utah is that between these two states, there are another 7 others in a row. The digit 7 appears in even more cases on the image, particularly, 7 is the first digit in the car number: 7832; and 7 is present in the phone number: 1-877-337-2017. Based on these evidences, it turns out that digit 7 may be the clue to decoding the encrypted data in the image. Practically, in many decryption / encryption software, the clue is related to specific number of charts / strings. This principle lets to decrypt data according to some set of rules, rather than based on random variations. For example, Franz Scheerer (2014), practically uses the principle of adding +7 for variations of data coded, based on the principle suggested by Morris Dworkin (2010), when “the input strings to encryption and decryption for each of the variants may be any string whose length is not less than b bits, but typically an implementation is designed to accept a restricted set of lengths.” This means applying sets of restrictions to multiples of 7/8, “so that the input strings may be represented with bytes/octets” to make lengths of data still valid and readable even after decryption:

#!/usr/bin/env python

Copyright (c) 2014 Scheerer Software

# Author: Franz Scheerer

the GNU General Public License as published by

# the Free Software Foundation;

def Efile(nam, keytxt):

keyn = 117

for char in keytxt:

keyn = 256 * keyn + ord(char)

f = open(nam,'r')

data = f.read()

cipher = CollatzE(data, keyn)


fnam = nam + '.enc'

f = open(fnam, 'w' )



def Dfile(nam, keytxt):

keyn = 117

for char in keytxt:

keyn = 256 * keyn + ord(char)

fnam = nam + '.enc'

f = open(fnam,'r')

cipher = f.read()

data = CollatzD(cipher, keyn)


f = open(nam, 'w')



def CollatzE(data, key):

up = 3**90

low = 2**42 + 7

out = []

for char in data:

byval = 0

for bit in range(8):

if key < low:

while key < up:

key = key**2 + 7

if key % 2:

key = (3*key+1)/2


key = key/2

byval = byval + ((key & 1)

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