%% First step: Necessary things
close all;
clear all;
clc;


%% RSA encryption

%% Encryption & Decryption Key
e = 23;
d = 47;
n = 143;
                %%step: Taking input
                        %(1)---------------Input as random number----------------------
                        %noOfSymbol = 1000;
                        %symbols = randi(1,noOfSymbol,256);

                        %(2)---------------Input as Text----------------------
                        temp = 'Enter your input: ';
                        text=input(temp,'s');
                        text2 = text
                        text3 = text
                        symbols = double(text);

                        %% RSA Encryption
                        b = symbols;
                        for i = 1:1:(e - 1);
                            symbols = symbols .* b;
                            symbols = mod(symbols, n);
                        end
                %% step: Converting decimal to binary
                symbolsToBitMapping = de2bi(symbols,8,'left-msb');
                totalBits = numel(symbolsToBitMapping);
                inReshapedBits = reshape(symbolsToBitMapping,1,totalBits);

                %% step: Zero Padding
                M=4;
                bps = log2(M);
                remainder = rem(totalBits,bps);
                if(remainder==0)
                   userDataPadding = inReshapedBits;
                else
                   paddedData = zeros(1, bps-remainder);
                   userDataPadding = [inReshapedBits,paddedData];
                end
                               % numel(reshapedBits)
                               % numel(userDataPadding)

                %% step: Modulation
                bitToSymbolMapping = reshape(userDataPadding,numel(userDataPadding)/bps,bps);
                decimalSymbol = bi2de(bitToSymbolMapping,'left-msb');
                modulatedSymbol = pskmod(decimalSymbol,M);

      %% step: Channel
      SN = [];
      BR = [];
      for snr = 0:12
          SN = [SN,snr]
                noisySymbols = awgn(modulatedSymbol,snr,'measured');
                %% Seventh step: Demodulation
                demodulatedSymbols = pskdemod(noisySymbols,M);
                decimalToBinary = de2bi(demodulatedSymbols,'left-msb');

                %% Eight step: Remove Zero Padding
                outReshapeBits = reshape(decimalToBinary,1,numel(decimalToBinary));
                outReshapeBits = outReshapeBits(1:totalBits);
                                %numel(outReshapeBits)

                %% Ninth step: Calculate BER
                [numberOfError, BER] = biterr(inReshapedBits,outReshapeBits);
          BR = [BR, BER];
     end

                %% step: Original symbols/text
                outReshapeBits = reshape(outReshapeBits,numel(outReshapeBits)/8,8);

                        decimalSymbols = bi2de(outReshapeBits,'left-msb');
                        c = decimalSymbols

                        %% Decryption
                        for i = 1:1:(d-1);
                            decimalSymbols = decimalSymbols .* c;
                            decimalSymbols = mod(decimalSymbols, n);
                        end
                        text = char(decimalSymbols)';




                     %% No Encryption


                        %% Second step: Taking input
                        %(1)---------------Input as random number----------------------
                        %noOfSymbol = 1000;
                        %symbols = randi(1,noOfSymbol,256);

                        %(2)---------------Input as Text----------------------
                        symbols = double(text2);


                %% Third step: Converting decimal to binary
                symbolsToBitMapping = de2bi(symbols,8,'left-msb');
                totalBits = numel(symbolsToBitMapping);
                inReshapedBits = reshape(symbolsToBitMapping,1,totalBits);

                %% Fourth step: Zero Padding
                M=4;
                bps = log2(M);
                remainder = rem(totalBits,bps);
                if(remainder==0)
                   userDataPadding = inReshapedBits;
                else
                   paddedData = zeros(1, bps-remainder);
                   userDataPadding = [inReshapedBits,paddedData];
                end
                               % numel(reshapedBits)
                               % numel(userDataPadding)

                %% Fifth step: Modulation
                bitToSymbolMapping = reshape(userDataPadding,numel(userDataPadding)/bps,bps);
                decimalSymbol = bi2de(bitToSymbolMapping,'left-msb');
                modulatedSymbol = pskmod(decimalSymbol,M);

      %% Sixth step: Channel
      SN1 = [];
      BR1 = [];
      for snr = 0:12
          SN1 = [SN1,snr]
                noisySymbols = awgn(modulatedSymbol,snr,'measured');
                %% Seventh step: Demodulation
                demodulatedSymbols = pskdemod(noisySymbols,M);
                decimalToBinary = de2bi(demodulatedSymbols,'left-msb');

                %% Eight step: Remove Zero Padding
                outReshapeBits = reshape(decimalToBinary,1,numel(decimalToBinary));
                outReshapeBits = outReshapeBits(1:totalBits);
                                %numel(outReshapeBits)

                %% Ninth step: Calculate BER
                [numberOfError, BER1] = biterr(inReshapedBits,outReshapeBits);
          BR1 = [BR1, BER1];
     end

                %% Tenth step: Original symbols/text
                outReshapeBits = reshape(outReshapeBits,numel(outReshapeBits)/8,8);

                        decimalSymbols = bi2de(outReshapeBits,'left-msb');
                        c = decimalSymbols
                        text = char(decimalSymbols)';








                      %% Ceaser Cipher Encrypion




                         %% Second step: Taking input
                        %(1)---------------Input as random number----------------------
                        %noOfSymbol = 1000;
                        %symbols = randi(1,noOfSymbol,256);

                        %(2)---------------Input as Text----------------------
                        symbols = double(text3);


                %% Third step: Converting decimal to binary
                symbolsToBitMapping = de2bi(symbols,8,'left-msb');
                totalBits = numel(symbolsToBitMapping);
                inReshapedBits = reshape(symbolsToBitMapping,1,totalBits);

                %% Fourth step: Zero Padding
                M=4;
                bps = log2(M);
                remainder = rem(totalBits,bps);
                if(remainder==0)
                   userDataPadding = inReshapedBits;
                else
                   paddedData = zeros(1, bps-remainder);
                   userDataPadding = [inReshapedBits,paddedData];
                end
                               % numel(reshapedBits)
                               % numel(userDataPadding)

                %% Fifth step: Modulation
                bitToSymbolMapping = reshape(userDataPadding,numel(userDataPadding)/bps,bps);
                decimalSymbol = bi2de(bitToSymbolMapping,'left-msb');
                modulatedSymbol = pskmod(decimalSymbol,M);

      %% Sixth step: Channel
      SN3 = [];
      BR3 = [];
      for snr = 0:12
          SN3 = [SN3,snr]
                noisySymbols = awgn(modulatedSymbol,snr,'measured');
                %% Seventh step: Demodulation
                demodulatedSymbols = pskdemod(noisySymbols,M);
                decimalToBinary = de2bi(demodulatedSymbols,'left-msb');

                %% Eight step: Remove Zero Padding
                outReshapeBits = reshape(decimalToBinary,1,numel(decimalToBinary));
                outReshapeBits = outReshapeBits(1:totalBits);
                                %numel(outReshapeBits)

                %% Ninth step: Calculate BER
                [numberOfError, BER3] = biterr(inReshapedBits,outReshapeBits);
          BR3 = [BR3, BER3];
     end

                %% Tenth step: Original symbols/text
                outReshapeBits = reshape(outReshapeBits,numel(outReshapeBits)/8,8);

                        decimalSymbols = bi2de(outReshapeBits,'left-msb');
                        c = decimalSymbols
                        text = char(decimalSymbols)';


    %% SNR vs BER plot
    plotHandle=plot(SN1,BR1,'k-o');
    set(plotHandle,'LineWidth',1.5);
    hold on;
    plotHandle=plot(SN,BR,'r-o');
    set(plotHandle,'LineWidth',1.5);
    plotHandle=plot(SN3,BR3,'g-o');
    set(plotHandle,'LineWidth',1.5);