Question

python programming

• Appropriate and well constructed while and/or for loops (as necessary). • Appropriate if, if-else, if-elif-else statements (as necessary). • The use of the ord() and chr() functions (as necessary). • The following three functions (refer to stage 6 for description): o display_details() o get_menu_choice() o get_offset() • Output that strictly adheres to the assignment specifications. If you are not sure about these details, you should check with the ‘Sample Output – Part II’ provided at the end of this document. • Good programming practice: o Consistent commenting, layout and indentation. You are to provide comments to describe: your details, program description, all variable definitions, and significant sections of code. o Meaningful variable names. • Your solutions MAY make use of the following built-in functions and methods: o Any of the Python built-in functions… specifically, you may find you may need the following: int(), input(), print(), range(), ord(),and chr(). • Your solutions MAY ALSO make use of the following: o Concatenation (+) operator to create/build new strings. o Access the individual elements in a string with an index (one element only). i.e. string_name[index]. o Your own (user-defined) functions (in addition to the three functions listed above). Your solutions MUST NOT use: • break, or continue statements in your solution. Do not use the quit() or exit() functions or the break or return statements (or any other techniques) as a way to break out of loops. Doing so will result in a significant mark deduction.

Sample output

*** Menu ***

1. Encrypt string

2. Decrypt string

3. Brute force decryption

4. Quit

What would you like to do [1,2,3,4]? 1

Please enter string to encrypt: Elvis has left the building!

Please enter offset value (1 to 94): 3

Encrypted string: Hoylv#kdv#ohiw#wkh#exloglqj$

*** Menu ***

1. Encrypt string

2. Decrypt string

3. Brute force decryption

4. Quit What would you like to do [1,2,3,4]? 2

Please enter string to decrypt: Hoylv#kdv#ohiw#wkh#exloglqj$ Please enter offset value (1 to 94): 3

Decrypted string: Elvis has left the building!

*** Menu ***

1. Encrypt string

2. Decrypt string

3. Brute force decryption

4. Quit What would you like to do [1,2,3,4]? 3

Please enter string to decrypt: Hoylv#kdv#ohiw#wkh#exloglqj$

Offset: 1 = Decrypted string: Gnxku"jcu"nghv"vjg"dwknfkpi# Offset: 2 = Decrypted string: Fmwjt!ibt!mfgu!uif!cvjmejoh" Offset: 3 = Decrypted string: Elvis has left the building! Offset: 4 = Decrypted string: Dkuhr~g`r~kdes~sgd~athkchmf Offset: 5 = Decrypted string: Cjtgq}f_q}jcdr}rfc}`sgjbgle~ Offset: 6 = Decrypted string: Bisfp|e^p|ibcq|qeb|_rfiafkd} Offset: 7 = Decrypted string: Ahreo{d]o{habp{pda{^qeh`ejc| Offset: 8 = Decrypted string: @gqdnzc\nzg`aozoc`z]pdg_dib{ Offset: 9 = Decrypted string: ?fpcmyb[myf_`nynb_y\ocf^chaz Offset: 10 = Decrypted string: >eoblxaZlxe^_mxma^x[nbe]bg`y Offset: 11 = Decrypted string: =dnakw`Ykwd]^lwl`]wZmad\af_x Offset: 12 = Decrypted string: P\IBCQ\QEB\?RFIAFKD] Offset: 39 = Decrypted string: !HREO[D=O[HABP[PDA[>QEH@EJC\ Offset: 40 = Decrypted string: GQDNZCCHAZ Offset: 42 = Decrypted string: }EOBLXA:LXE>?MXMA>X;NBE=BG@Y Offset: 43 = Decrypted string: |DNAKW@9KWD=>LWL@=W:MADW Offset: 45 = Decrypted string: zBL?IU>7IUB;;U8K?B:?D=V Offset: 46 = Decrypted string: yAK>HT=6HTA:;ITI=:T7J>A9>CH;EQ:3EQ>78FQF:7Q4G;>6;@9R Offset: 50 = Decrypted string: u=G:DP92DP=67EPE96P3F:=5:?8Q Offset: 51 = Decrypted string: t7P Offset: 52 = Decrypted string: s;E8BN70BN;45CNC74N1D8;38=6O Offset: 53 = Decrypted string: r:D7AM6/AM:34BMB63M0C7:27<5N Offset: 54 = Decrypted string: q9C6@L5.@L923ALA52L/B6916;4M Offset: 55 = Decrypted string: p8B5?K4-?K812@[email protected]:3L Offset: 56 = Decrypted string: o7A4>J3,>J701?J?30J-@47/492K Offset: 57 = Decrypted string: n6@3=I2+=I6/0>I>2/I,?36.381J Offset: 58 = Decrypted string: m5?2

25-270I Offset: 59 = Decrypted string: l4>1;G0);G4-.' 2>+$%3>3'$>!4(+#(-&? Offset: 69 = Decrypted string: b*4'1=&~1=*#$2=2= 3'*"',%> Offset: 70 = Decrypted string: a)3&0<%}0<)"#1<1%"<~2&)!&+$= Offset: 71 = Decrypted string: `(2%/;$|/;(!"0;0$!;}1%( %*#< Offset: 72 = Decrypted string: _'1$.:#{.:' !/:/# :|0$'~$)"; Offset: 73 = Decrypted string: ^&0#-9"z-9&~ .9."~9{/#&}#(!: Offset: 74 = Decrypted string: ]%/",8!y,8%}~-8-!}8z."%|"' 9 Offset: 75 = Decrypted string: \$.!+7 x+7$|},7, |7y-!${!&~8 Offset: 76 = Decrypted string: [#- *6~w*6#{|+6+~{6x, #z %}7 Offset: 77 = Decrypted string: Z",~)5}v)5"z{*5*}z5w+~"y~$|6 Offset: 78 = Decrypted string: Y!+}(4|u(4!yz)4)|y4v*}!x}#{5 Offset: 79 = Decrypted string: X *|'3{t'3 xy(3({x3u)| w|"z4 Offset: 80 = Decrypted string: W~){&2zs&2~wx'2'zw2t({~v{!y3 Offset: 81 = Decrypted string: V}(z%1yr%1}vw&1&yv1s'z}uz x2 Offset: 82 = Decrypted string: U|'y$0xq$0|uv%0%xu0r&y|ty~w1 Offset: 83 = Decrypted string: T{&x#/wp#/{tu$/$wt/q%x{sx}v0 Offset: 84 = Decrypted string: Sz%w".vo".zst#.#vs.p$wzrw|u/ Offset: 85 = Decrypted string: Ry$v!-un!-yrs"-"ur-o#vyqv{t. Offset: 86 = Decrypted string: Qx#u ,tm ,xqr!,!tq,n"uxpuzs- Offset: 87 = Decrypted string: Pw"t~+sl~+wpq + sp+m!twotyr, Offset: 88 = Decrypted string: Ov!s}*rk}*vop~*~ro*l svnsxq+ Offset: 89 = Decrypted string: Nu r|)qj|)uno})}qn)k~rumrwp* Offset: 90 = Decrypted string: Mt~q{(pi{(tmn|(|pm(j}qtlqvo) Offset: 91 = Decrypted string: Ls}pz'ohz'slm{'{ol'i|pskpun( Offset: 92 = Decrypted string: Kr|oy&ngy&rklz&znk&h{orjotm' Offset: 93 = Decrypted string: Jq{nx%mfx%qjky%ymj%gznqinsl& Offset: 94 = Decrypted string: Ipzmw$lew$pijx$xli$fymphmrk%

*** Menu ***

1. Encrypt string

2. Decrypt string

3. Brute force decryption

4. Quit What would you like to do [1,2,3,4]? 4 Goodbye.

Note: Your program must work with the printable ASCII character set. That is, all the characters from ASCII 32 (Space) to ASCII 126 (~). When the offset points to a character beyond 126 it should wrap around to the beginning of the set.

Answer 1

# display menu options
def display_details():
    print('***Menu***')
    print('1. Encrypt string')
    print('2. Decrypt string')
    print('3. Brute force decryption')
    print('4. Quit')


# returns a number from 1 to 4 indicating menu option
def get_menu_choice():
    # prompt user for input
    choice = input('What would you like to do [1,2,3,4]? ')
    # validate user input
    if choice.isdigit():
        option = int(choice)
        # check if option is in valid range
        if (option < 5) and (option > 0):
            # return valid input
            return option
        else:
            # option is not in valid range
            # print error and try again
            print('Invalid Input!')
            return get_menu_choice()
    else:
        # non digit character received
        # print error message
        print('Invalid Input!')
        # try again for valid input
        return get_menu_choice()


# returns a number from 1 to 94 indicating offset value
def get_offset():
    # prompt user for input
    choice = input('Please enter offset value (1 to 94): ')
    # validate user input
    if choice.isdigit():
        option = int(choice)
        # check if option is in valid range
        if (option < 95) and (option > 0):
            # return valid input
            return option
        else:
            # option is not in valid range
            # print error and try again
            print('Invalid Input!')
            return get_offset()
    else:
        # non digit character received
        # print error message
        print('Invalid Input!')
        # try again for valid input
        return get_offset()


# Encrypts a given string with given offset
# increase each character value in the string to given offset
# prints resulting string
def encrypt(message, offset):
    # create a string to print
    encoded = ''
    # loop through message and increase its character values
    for i in range(len(message)):
        # get integer value of individual character
        value = ord(message[i])
        # increase value to offset
        value = value + offset
        # check if value is in printable range
        if value > 126:
            # wrap value at start
            value = value - 93
        # get character of the new value
        character = chr(value)
        # build string character by character
        encoded = encoded + character
    # print encoded message
    print('Encrypted string: ' + encoded)


# Decrypts a given string with given offset
# decrease each character value in the string to given offset
# prints resulting string
def decrypt(message, offset):
    # create a string to print
    decoded = ''
    # loop through message and decrease its character values
    for i in range(len(message)):
        # get integer value of individual character
        value = ord(message[i])
        # decrease value to offset
        value = value - offset
        # check if value is in printable range
        if value < 32:
            # wrap value at end
            value = value + 95
        # get character of the new value
        character = chr(value)
        # build string character by character
        decoded = decoded + character
    # print decoded message
    print('Decrypted string: ' + decoded)


# main function to run the program
def main():
    # prompt user for input till Quit is selected
    option = 0  # initialize value to enter in loop
    while option != 4:
        display_details()
        option = get_menu_choice()
        # check user selected option
        if option == 1:
            # user selected to Encrypt string
            # ask user for a string to encrypt
            message = input('Please enter string to encrypt: ')
            encrypt(message, get_offset())
        elif option == 2:
            # user selected to Decrypt string
            # ask user for a string to decrypt
            message = input('Please enter string to decrypt: ')
            decrypt(message, get_offset())
        elif option == 3:
            # user selected to brute force decryption
            # ask user for a string to decrypt
            message = input('Please enter string to decrypt: ')
            # try every offset from 1 to 94 to decrypt the message
            for i in range(94):
                # print each offset tried
                print('Offset:', end=' ')
                print(i+1, end=' = ')
                decrypt(message, i+1)
        else:
            # when option is Quit print end message
            print('Goodbye')


# run the program
main()

let me know if you have any doubts or problem running the code.