代写代做python简单加密程序、python Encryption Assignment代写

日期：2018-08-23 09:24

Simple Encryption

Assignment 1

CSSE1001/7030

Semester 2, 2018

Version 1.0.0

10 marks (5%)

Due Friday 24th August, 2018, 20:30

1. Introduction

This assignment provides you the opportunity to apply foundational concepts taught at the beginning of the course by writing a piece

of software to encrypt and decrypt text.

Text is encrypted with a simple cipher where each letter of the alphabet is replaced with another letter that occurs a fixed number of

letters later. This fixed number is known as the coding offset.

If the coding offset is 3, for example, is replaced with , is replaced with , is replaced with , etc., as shown below:

2. Assignment Tasks

2.1. Example Output

Some example output has been truncated and replaced with ellipses (...). Any lines that have been wrapped onto the next after

exceeding the width of this document should be treated as a single line.

a d b e z c

Encrypting with a Coding Offset of 3

Welcome to the simple encryption tool!

Please choose an option [e/d/a/q]:

e) Encrypt some text

d) Decrypt some text

a) Automatically decrypt English text

q) Quit

> e

Please enter some text to encrypt: you will always remember this as the day

Please enter a shift offset (1-25): 7

The encrypted text is: fvb dpss hsdhfz yltltily aopz hz aol khf

Please choose an option [e/d/a/q]:

e) Encrypt some text

d) Decrypt some text

a) Automatically decrypt English text

q) Quit

> d

Please enter some text to decrypt: asdf ghjkl qwerty uiop z xcvbnm

Please enter a shift offset (1-25): 17

The decrypted text is: jbmo pqstu zfnach drxy i glekwv

Please choose an option [e/d/a/q]:

e) Encrypt some text

2.2. Getting Started

Download the following files and place them in the same directory:

: The main assignment file - write your code here

: Contains useful supporting functions

: A list of all words considered English

2.3. Design

You are expected to use good programming practice in your code and you must incorporate at least the following functions. You can

assume that:

text contains only spaces and letters of the English alphabet (both upper & lowercase)

the coding offset is between 1 and 25, inclusive

2.3.1. encrypt

encrypt(text, offset) -> str

d) Decrypt some text

a) Automatically decrypt English text

q) Quit

> d

Please enter some text to decrypt: a bmkl kso lzw sv sfv lzgmyzl al dggcwv xmf

Please enter a shift offset (1-25): 18

The decrypted text is: i just saw the ad and thought it looked fun

Please choose an option [e/d/a/q]:

e) Encrypt some text

d) Decrypt some text

a) Automatically decrypt English text

q) Quit

> ep zpv tff uiptf uxp xffwjmt epdups

Invalid command

Please choose an option [e/d/a/q]:

e) Encrypt some text

d) Decrypt some text

a) Automatically decrypt English text

q) Quit

> a

Please enter some encrypted text: ep zpv tff uiptf uxp xffwjmt epdups

Encryption offset: 1

Decrypted message: do you see those two weevils doctor

Please choose an option [e/d/a/q]:

e) Encrypt some text

d) Decrypt some text

a) Automatically decrypt English text

q) Quit

> a

Please enter some encrypted text: nmd

Multiple encryption offsets: 4, 12, 21, 25

Please choose an option [e/d/a/q]:

e) Encrypt some text

d) Decrypt some text

a) Automatically decrypt English text

q) Quit

> a

Please enter some encrypted text: asdf ghjkl qwerty uiop z xcvbnm

No valid encryption offset

Please choose an option [e/d/a/q]:

e) Encrypt some text

d) Decrypt some text

a) Automatically decrypt English text

q) Quit

> q

Bye!

a1.py

a1_support.py

words.txt

Encrypts by replacing each letter with the letter some fixed number of positions (the ) down the alphabet. Returns the

encrypted text.

2.3.2. decrypt

decrypt(text, offset) -> str

Decrypts that was encrypted by the function above. Returns the decrypted text.

2.3.3. find_encryption_offsets

find_encryption_offsets(encrypted_text) -> tuple<int, ...>

Returns a tuple containing all possible offsets that could have been used if to encrypt some English text into .

2.3.4. main

main() -> None

Handles top-level interaction with user, as outlined in 2.1. Example Output. You may assume that the user will always enter at least

one word each time, and that they will always choose a valid offset (between 1 and 25, inclusive).

3. Extension

Extend the program to accept as an input when a shift offset is requested. If the user types this, encrypted/decrypted text should

be shown for all offsets (1 to 25, inclusive), as shown below:

text offset

>>> encrypt("you will always remember this as the day", 7)

'fvb dpss hsdhfz yltltily aopz hz aol khf'

>>> encrypt("music is the shorthand of emotion", 2)

'owuke ku vjg ujqtvjcpf qh goqvkqp'

>>> encrypt("qgnrag hgorkey gtj cnovvkj ixkgs", 9)

'zpwajp qpxatnh pcs lwxeets rgtpb'

text encrypt

>>> decrypt("a bmkl kso lzw sv sfv lzgmyzl al dggcwv xmf", 17)

'j kvtu tbx uif be boe uipvhiu ju mpplfe gvo'

>>> decrypt("a bmkl kso lzw sv sfv lzgmyzl al dggcwv xmf", 18)

'i just saw the ad and thought it looked fun'

>>> decrypt("asdf ghjkl qwerty uiop z xcvbnm", 17)

'jbmo pqstu zfnach drxy i glekwv'

encrypted_text

>>> find_encryption_offsets("iynjo fuhsudj ev jxu jycu yj mehai qbb jxu jycu")

(16,)

>>> find_encryption_offsets("vftg amnl aqkkxmn mjmcqlm emkveoxtmn lvbmlomz")

()

>>> find_encryption_offsets("nmd")

(4, 12, 21, 25)

0

...

> e

Please enter some text to encrypt: all we can do is smile back

Please enter a shift offset (1-25): 0

The encrypted text is:

01: bmm xf dbo ep jt tnjmf cbdl

02: cnn yg ecp fq ku uokng dcem

03: doo zh fdq gr lv vploh edfn

04: epp ai ger hs mw wqmpi fego

05: fqq bj hfs it nx xrnqj gfhp

06: grr ck igt ju oy ysork hgiq

07: hss dl jhu kv pz ztpsl ihjr

08: itt em kiv lw qa auqtm jiks

09: juu fn ljw mx rb bvrun kjlt

10: kvv go mkx ny sc cwsvo lkmu

11: lww hp nly oz td dxtwp mlnv

12: mxx iq omz pa ue eyuxq nmow

13: nyy jr pna qb vf fzvyr onpx

14: ozz ks qob rc wg gawzs poqy

15: paa lt rpc sd xh hbxat qprz

16: qbb mu sqd te yi icybu rqsa

17: rcc nv tre uf zj jdzcv srtb

18: sdd ow usf vg ak keadw tsuc

19: tee px vtg wh bl lfbex utvd

20: uff qy wuh xi cm mgcfy vuwe

Further, extend the functions in 2.3. Design to accept all characters (not just English letters and spaces). These characters should be

ignored when encrypting or decrypting. When automatically decrypting English text:

Ignore contractions (words containing an apostrophe - i.e. we're, you've, goose's, etc.)

Treat words joined together by a hyphen or dash as separate words (i.e. sea-song is treated as two words: sea & song)

For example:

4. Marking Criteria

In addition to providing a working solution to the assignment problem, you are required to discuss their submission with a tutor. This

discussion will take place in the week following the assignment submission deadline, in the practical session in which you are

enrolled. You must attend this session. It is treated as an assessment item, so absence without reason may result in an overall mark

of zero for this assignment.

For each of the following criteria, part marks will be awarded if the criterion is not fully achieved.

Criteria Mark

Programming Constructs

Program is well structured and readable 1

Variable and function names are meaningful 1

Algorithmic logic is appropriate 1

Documentation

Entire program is documented clearly and concisely, without excessive or extraneous comments 2

Total /10

Functionality

Implements correct functionality with no serious errors 4

Extension

Implements extended functionality correctly 1

21: vgg rz xvi yj dn nhdgz wvxf

22: whh sa ywj zk eo oieha xwyg

23: xii tb zxk al fp pjfib yxzh

24: yjj uc ayl bm gq qkgjc zyai

25: zkk vd bzm cn hr rlhkd azbj

Please choose an option [e/d/a/q]:

e) Encrypt some text

...

...

> a

Please enter some encrypted text: X gtbtbqtg wxb addzxcv gdjcs iwt rdktg pcs lwxhiaxcv id wxbhtau ph wt sxs hd, pcs

iwtc qgtpzxcv dji xc iwpi das htp-hdcv iwpi wt hpcv hd duitc puitglpgsh: "Uxuittc btc dc iwt stps bpc'h rwthi; Ndwd-wd,

pcs p qdiiat du gjb!"

Encryption offset: 15

Decrypted message: I remember him looking round the cover and whistling to himself as he did so, and then breaking

out in that old sea-song that he sang so often afterwards: "Fifteen men on the dead man's chest; Yo-ho-ho, and a

bottle of rum!"

...

1,2

1,2

In order to be eligible for the marks for Programming Constructs & Documentation, you must have made a reasonable attempt at

implementing at the required functions.

See the course notes on Commenting.

5. Assignment Submission

Your assignment must be submitted via the assignment one submission link on Blackboard. You must only submit the file .

You may submit multiple times prior to the deadline, but only your most recent submission will be marked.

Late submission of the assignment will not be accepted. In the event of exceptional circumstances, you may submit a request for an

extension.

All requests for extension must be submitted on the UQ Application for Extension of Progressive Assessment form:

http://www.uq.edu.au/myadvisor/forms/exams/progressive-assessment-extension.pdf at least 48 hours prior to the submission

deadline. The application and supporting documentation must be submitted to the ITEE Coursework Studies office (78-425) or by

email to enquiries@itee.uq.edu.au.