enigma.m

The files included implement the M3 Enigma machine. Rotors.m implements the GUI and enigma.m impleme

function enigma(plugboard,rrSettings,message)
% plugboard is the string of plugboard settings
% rrSettings refers to rotor and reflector settings
% message refers to the message the user typed
% all are given as strings

% the following are for handling errors
% show an error message and open up the gui window again
if length(rrSettings) < 4
    rotors
    figure('Position',[285,200,270,160],'MenuBar','none', 'Name', 'Error!','NumberTitle','off');
    uicontrol('Style','text','String',...
        'Please select THREE rotors AND ONE reflector',...
        'Position',[5 5 260 150],'BackgroundColor','white',...
    'HorizontalAlignment', 'left','TooltipString', 'Your encrypted message is displayed here',...
    'FontSize', 13)
return
elseif length(message)==0 
    rotors
    figure('Position',[285,200,270,160],'MenuBar','none', 'Name', 'Error!','NumberTitle','off');
    uicontrol('Style','text','String',...
        'You REALLY need to enter a message for any decoding to occur!',...
        'Position',[5 5 260 150],'BackgroundColor','white',...
    'HorizontalAlignment', 'left','TooltipString', 'Your encrypted message is displayed here',...
    'FontSize', 13)
    return
elseif rem((length(plugboard)),2) ~=0
    rotors
    figure('Position',[285,200,270,160],'MenuBar','none', 'Name', 'Error!','NumberTitle','off');
    uicontrol('Style','text','String',...
        'The plugboard needs an even number of letters because each letter is matched with its adjacent. Please re-enter your data!',...
        'Position',[5 5 260 150],'BackgroundColor','white',...
    'HorizontalAlignment', 'left','TooltipString', 'Your encrypted message is displayed here',...
    'FontSize', 13)
    return
end


%***********************************************************************
% handle backspaces in user's input
newmessage=[];
nummessage=double(message);
for i=1:length(nummessage)
    if nummessage(i)~=32 %32 is the ascci code for the spacebar
        newmessage=[newmessage, nummessage(i)];
    end
end




%***********************************************************************
%below i am defining all the rotors
r1= ['E' 'K' 'M' 'F' 'L' 'G' 'D' 'Q' 'V' 'Z' 'N' 'T' 'O' 'W' 'Y' ...
        'H' 'X' 'U' 'S' 'P' 'A' 'I' 'B' 'R' 'C' 'J'];

r2=['A' 'J' 'D' 'K' 'S' 'I' 'R' 'U' 'X' 'B' 'L' 'H' 'W' 'T' 'M'...
        'C' 'Q' 'G' 'Z' 'N' 'P' 'Y' 'F' 'V' 'O' 'E'];

r3=['B' 'D' 'F' 'H' 'J' 'L' 'C' 'P' 'R' 'T' 'X' 'V' 'Z' 'N' ...
        'Y' 'E' 'I' 'W' 'G' 'A' 'K' 'M' 'U' 'S' 'Q' 'O'];

r4=['E' 'S' 'O' 'V' 'P' 'Z' 'J' 'A' 'Y' 'Q' 'U' 'I' 'R' ...
        'H' 'X' 'L' 'N' 'F' 'T' 'G' 'K' 'D' 'C' 'M' 'W' 'B'];

r5=['V' 'Z' 'B' 'R' 'G' 'I' 'T' 'Y' 'U' 'P' 'S' 'D' 'N' 'H' ...
        'L' 'X' 'A' 'W' 'M' 'J' 'Q' 'O' 'F' 'E' 'C' 'K'];

r6=['J' 'P' 'G' 'V' 'O' 'U' 'M' 'F' 'Y' 'Q' 'B' 'E' 'N'...
        'H' 'Z' 'R' 'D' 'K' 'A' 'S' 'X' 'L' 'I' 'C' 'T' 'W'];

r7=['N' 'Z' 'J' 'H' 'G' 'R' 'C' 'X' 'M' 'Y' 'S' 'W' 'B'...
        'O' 'U' 'F' 'A' 'I' 'V' 'L' 'P' 'E' 'K' 'Q' 'D' 'T'];

r8= ['F' 'K' 'Q' 'H' 'T' 'L' 'X' 'O' 'C' 'B' 'J' 'S'...
        'P' 'D' 'Z' 'R' 'A' 'M' 'E' 'W' 'N' 'I' 'U' 'Y' 'G' 'V'];


% and the keyboard we will use to index the input given by the user
kbrd=['A' 'B' 'C' 'D' 'E' 'F' 'G' 'H' 'I' 'J' 'K' 'L' 'M' 'N' 'O' 'P' ...
        'Q' 'R' 'S' 'T' 'U' 'V' 'W' 'X' 'Y' 'Z']; 

%***********************************************************************
% this section handles the reflector chosen by the user

if rrSettings(end)=='b' % settings of reflector b
    reflector= ['A' 'Y' 'B' 'R' 'C' 'U' 'D' 'H' 'E' 'Q' 'F' 'S'...
            'G' 'L' 'I' 'P' 'J' 'X' 'K' 'N' 'M' 'O' 'T' 'Z' 'V' 'W'];
else % settings of reflector c
    reflector= ['A' 'F' 'B' 'V' 'C' 'P' 'D' 'J' 'E' 'I' 'G' 'O' 'H' 'Y' 'K' 'R'...
            'L' 'Z' 'M' 'X' 'N' 'W' 'T' 'Q' 'S' 'U'];
end

%***********************************************************************
% this section handles the rotors
rotors=[{r1} {r1} {r1}]; % can assign whatever we want to rotors for now
% we just need 3 places to put the 3 rotors

% compare the radiobutton choice given as a string to the number of rotors
% if the match, we know what rotor the user picked
% put the rotor data in the cell array rotors
% do this three times for all rotor choices.
for i=1:3
    if str2num(rrSettings(i))==1
        rotors{i}=r1;
    elseif str2num(rrSettings(i))==2
        rotors{i}=r2;
    elseif str2num(rrSettings(i))==3
        rotors{i}=r3;
    elseif str2num(rrSettings(i))==4
        rotors{i}=r4;
    elseif str2num(rrSettings(i))==5
        rotors{i}=r5;
    elseif str2num(rrSettings(i))==6
        rotors{i}=r6;
    elseif str2num(rrSettings(i))==7
        rotors{i}=r7;
    else rotors{i}=r8;
        
    end
end
   
%do the assignment

crotor1=rotors(1);
crotor2=rotors(2);
crotor3=rotors(3);

%turn them into vectors - makes the manipulation easier
rotor1=crotor1{1};
rotor2=crotor2{1};
rotor3=crotor3{1};

% now we have the rotors chosen by the user

%***********************************************************************
% this section applies the plugboard transformation

if length(plugboard)~=0
    for k=1:2:length(plugboard)
        for i=1:length(newmessage)
            if plugboard(k)==newmessage(i)
                newmessage(i)=plugboard(k+1);
            end
        end
    end
end

% now  the message given by the user has gone through the plugboard and
% has been adjusted accordingly
%***********************************************************************

% we are now ready to apply the rotor and reflector transformations
% the following are the transformations through the rotors and through the reflector
% the second set of transformations when the characters pass through the rotors the
% second time will be taken care of in the next section

% counters below are set to move the rotors
counter1=0;
counter2=0;
counter3=0;


%first convert newmessage into characters and provide space for the final encoding
newmessage=char(newmessage);
semiencoded=[];

for i=1:length(newmessage) % do the stuff that follows for all letters
    
    % apply transformation from rotor 1
    for k=1:length(kbrd)
        if newmessage(i)==kbrd(k)
            rotor1=[rotor1(2:end), rotor1(end-((length(rotor1))-1))]; %shift rotor by one place
            semiencoded(i)=rotor1(k);
            break
        end
    end
    
    % apply transformation from rotor  2
    for j=1:length(kbrd)
        if  semiencoded(i)==kbrd(j) 
            % also check if counter==26, if so move position of rotor2 
            %and increment counter2 by 1
            if counter1==26
                counter2=counter2 + 1;
            elseif counter2==27
                counter2= 1; % initialize it
                rotor2=[rotor2(2:end), rotor2(end-((length(rotor2))-1))]; % shift rotor by one place
            end
            
            
            semiencoded(i)=rotor2(j);
            break
        end
    end
    
 
    
    
    % apply transformation from rotor 3
    for f=1:length(kbrd)
        if semiencoded(i)==kbrd(f) % also check counter 2 and if>26
            
            if counter2==26
                counter3=counter3 + 1;
            elseif counter2==27
                counter3= 1; % initialize it
                rotor3=[rotor3(2:end), rotor3(end-((length(rotor3))-1))]; % shift rotor by one place
            end
            semiencoded(i)=rotor3(f);
            break
        end
    end
    
    
    % apply transformation from the reflector
    for m=1:length(reflector)
        if semiencoded(i)==reflector(m) % if we find the letter
            even=[2  4  6  8  10  12  14  16  18  20  22  24  26];
            if sum(m == even) > 0 
                % and the letter is in an odd place, then we substitute with the 
                % letter that comes after it.                
                index=m-1;
                semiencoded(i)=reflector(index);
                break
            else
                % otherwise we substitute with the letter that comes before it
                index=m+1;
                semiencoded(i)=reflector(index);
                break
            end
        end           
    end
    
        % apply transformation going back through rotors- rotor3
        for k=1:length(rotor3)
        if semiencoded(i)==rotor3(k)
            semiencoded(i)=kbrd(k);
            break
        end
    end
    
            % apply transformation going back through rotors- rotor2
        for j=1:length(rotor2)
            if  semiencoded(i)==rotor2(j)
            semiencoded(i)=kbrd(j);
            break
        end
    end
    
    % apply transformation going back through rotors- rotor1
    for f=1:length(rotor1)
        if semiencoded(i)==rotor1(f)
            semiencoded(i)=kbrd(f);
            break
        end
    end
end

%***********************************************************************

msg=char(semiencoded);
    figure('Position',[65,200,700,80],'MenuBar','none', 'Name', 'Enigma: The encoded message','NumberTitle','off');
    uicontrol('Style','text','String',msg,...
        'Position',[5 5 690 70],'BackgroundColor','white',...
    'HorizontalAlignment', 'left','TooltipString', 'Enigma: The ciphertext depending on the input you gave',...
    'FontSize', 12)