Please follow the link below to start this AES lab assignment using the tripple S-DES mode below.

http://williamstallings.com/Crypto/AESCalc/AESlab.html

function [varargout] = DES(input64,mode,key)

%DES: Data Encryption Standard % Encrypt/Decrypt a 64-bit message using a 64-bit key using the Feistel Network % ------------------------------------------------------------------------- % Inputs: % input64 = a 64-bit message % mode = either 'ENC' encryption or 'DEC' decryption (default 'ENC') % key = a 56/64-bit key (optional under 'ENC', but mandatory under 'DEC') % Outputs: % varargout{1} = output64, a 64-bit message after encryption/decryption % varargout{2} = a 64-bit key, if a 64-bit key is not provided as an input % ------------------------------------------------------------------------- % Demos: % plaintext = round(rand(1,64)); % [ciphertext,key] = DES(plaintext); % Encryption syntex 1 % [ciphertext1,key] = DES(plaintext,'ENC'); % Encryption syntex 2 % deciphertext1 = DES(ciphertext1,'DEC',key);% Decryption syntex % % key56 = round(rand(1,56)); % [ciphertext2,key64] = DES(plaintext,'ENC',key56);% Encryption syntex 3 (56-bit key) % deciphertext2 = DES(ciphertext2,'DEC',key64); % Decryption syntex (64-bit key) % ciphertext3 = DES(plaintext,'ENC',key64); % Encryption syntex 3 (64-bit key) % deciphertext3 = DES(ciphertext3,'DEC',key56); % Decryption syntex (56-bit key) % % % plot results % subplot(4,2,1),plot(plaintext),ylim([-.5,1.5]),xlim([1,64]),title('plaintext') % subplot(4,2,2),plot(ciphertext),ylim([-.5,1.5]),xlim([1,64]),title('ciphertext') % subplot(4,2,3),plot(deciphertext1),ylim([-.5,1.5]),xlim([1,64]),title('deciphertext1') % subplot(4,2,4),plot(ciphertext1),ylim([-.5,1.5]),xlim([1,64]),title('ciphertext1') % subplot(4,2,5),plot(deciphertext2),ylim([-.5,1.5]),xlim([1,64]),title('deciphertext2') % subplot(4,2,6),plot(ciphertext2),ylim([-.5,1.5]),xlim([1,64]),title('ciphertext2') % subplot(4,2,7),plot(deciphertext3),ylim([-.5,1.5]),xlim([1,64]),title('deciphertext3') % subplot(4,2,8),plot(ciphertext3),ylim([-.5,1.5]),xlim([1,64]),title('ciphertext3') % ------------------------------------------------------------------------- % NOTE: % 1. If a 64-bit key is provided, then its bit parities will be checked. If % a 56-bit key is provided, then it is automatically added 8 partity % checking bits. However, the 8 parity bits are never used in % DES encryption/decryption process. They are included just for the % completeness of a DES implementation. % 2. Cipher modes are not provided in this simple script. If you are % interested or do not know what does cipher modes mean, please go to page % http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation % for details. Please keep in mind that selecting an inappropriate working % mode may extremely weaken the security of your messages. % 3. A general description of DES can be found at its wiki page: % http://en.wikipedia.org/wiki/Data_Encryption_Standard % The detailed cryptographical primitives can be found under the page: % http://en.wikipedia.org/wiki/DES_supplementary_material % If you want to speed-up the DES code here, you can simply store these % primitives in memory and call them when you need. % ------------------------------------------------------------------------- % By Yue (Rex) Wu % ECE Dept @ Tufts Univ. % 08/18/2012 % If you find bugs, please email me via ywu03@ece.tufts.edu % ------------------------------------------------------------------------- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% 0. Initialization %% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % 0.1 check input error(nargchk(1,3,nargin)); switch nargin case 1 mode = 'ENC'; K = round(rand(8,7)); K(:,8) = mod(sum(K,2),2); % note these eight bits of key are never used in encryption K = reshape(K',1,64); varargout{2} = K; case 2 switch mode case 'ENC' K = round(rand(8,7)); K(:,8) = mod(sum(K,2),2); % note these eight bits of key are never used in encryption K = reshape(K',1,64); varargout{2} = K; case 'DEC' error('Key has to be provided in decryption mode (DEC)') otherwise error('WRONG working mode!!! Select either encrtyption mode: ENC or decryption mode: DEC !!!') end case 3 if isempty(setdiff(unique(key),[0,1])) % check provided key type if numel(key) == 64 % check provided key parity keyParityCheck = @(k) (sum(mod(sum(reshape(k,8,8)),2))==0); if keyParityCheck(key) == 1 K = key(:)'; else error('Key parity check FAILED!!!') end elseif numel(key) == 56 % add parity bits K = reshape(key,7,8)'; K(:,8) = mod(sum(K,2),2); % note these eight bits of key are never used in encryption K = reshape(K',1,64); varargout{2} = K; display('Key parity bits added') else error('Key has to be either 56 or 64-bit long!!!') end else error('Key has to be binary!!!') end end % 0.2 check message length and type if numel(input64) == 64 && isempty(setdiff(unique(input64),[0,1])) P = input64; else error('Message has to be a 64-bit message!!!') end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% 1. Cryptographical primitives %% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % 1.1 define splitting function HALF_L = @(message) message(1:32); HALF_R = @(message) message(33:64); % 1.2 define expansion function EF = @(halfMessage) [halfMessage([32,4:4:28])',(reshape(halfMessage,4,8))',halfMessage([5:4:29,1])']; % 1.3 define key mixing (KM) KM = @(expandedHalfMessage,rK) xor(expandedHalfMessage,reshape(rK,6,8)'); % 1.4 define eight substitution tables % input: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 st{1} = [14 4 13 1 2 15 11 8 3 10 6 12 5 9 0 7;... 0 15 7 4 14 2 13 1 10 6 12 11 9 5 3 8;... 4 1 14 8 13 6 2 11 15 12 9 7 3 10 5 0;... 15 12 8 2 4 9 1 7 5 11 3 14 10 0 6 13]; st{2} = [15 1 8 14 6 11 3 4 9 7 2 13 12 0 5 10;... 3 13 4 7 15 2 8 14 12 0 1 10 6 9 11 5;... 0 14 7 11 10 4 13 1 5 8 12 6 9 3 2 15;... 13 8 10 1 3 15 4 2 11 6 7 12 0 5 14 9]; st{3} = [10 0 9 14 6 3 15 5 1 13 12 7 11 4 2 8;... 13 7 0 9 3 4 6 10 2 8 5 14 12 11 15 1;... 13 6 4 9 8 15 3 0 11 1 2 12 5 10 14 7;... 1 10 13 0 6 9 8 7 4 15 14 3 11 5 2 12]; st{4} = [7 13 14 3 0 6 9 10 1 2 8 5 11 12 4 15;... 13 8 11 5 6 15 0 3 4 7 2 12 1 10 14 9;... 10 6 9 0 12 11 7 13 15 1 3 14 5 2 8 4;... 3 15 0 6 10 1 13 8 9 4 5 11 12 7 2 14]; st{5} = [2 12 4 1 7 10 11 6 8 5 3 15 13 0 14 9;... 14 11 2 12 4 7 13 1 5 0 15 10 3 9 8 6;... 4 2 1 11 10 13 7 8 15 9 12 5 6 3 0 14;... 11 8 12 7 1 14 2 13 6 15 0 9 10 4 5 3]; st{6} = [12 1 10 15 9 2 6 8 0 13 3 4 14 7 5 11;... 10 15 4 2 7 12 9 5 6 1 13 14 0 11 3 8;... 9 14 15 5 2 8 12 3 7 0 4 10 1 13 11 6;... 4 3 2 12 9 5 15 10 11 14 1 7 6 0 8 13]; st{7} = [4 11 2 14 15 0 8 13 3 12 9 7 5 10 6 1;... 13 0 11 7 4 9 1 10 14 3 5 12 2 15 8 6;... 1 4 11 13 12 3 7 14 10 15 6 8 0 5 9 2;... 6 11 13 8 1 4 10 7 9 5 0 15 14 2 3 12]; st{8} = [13 2 8 4 6 15 11 1 10 9 3 14 5 0 12 7;... 1 15 13 8 10 3 7 4 12 5 6 11 0 14 9 2;... 7 11 4 1 9 12 14 2 0 6 10 13 15 3 5 8;... 2 1 14 7 4 10 8 13 15 12 9 0 3 5 6 11]; % the eight binary s-boxes for i = 1:8 ST{i} = mat2cell(blkproc(st{i},[1,1],@(x) de2bi(x,4,'left-msb')),ones(1,4),ones(1,16)*4); end % 1.5 define subsitution function (SBOX) SUBS = @(expandedHalfMessage,blkNo) ST{blkNo}{bi2de(expandedHalfMessage(blkNo,[1,6]),'left-msb')+1,bi2de(expandedHalfMessage(blkNo,[2:5]),'left-msb')+1}; SBOX = @(expandedHalfMessage) [SUBS(expandedHalfMessage,1);SUBS(expandedHalfMessage,2);... SUBS(expandedHalfMessage,3);SUBS(expandedHalfMessage,4);... SUBS(expandedHalfMessage,5);SUBS(expandedHalfMessage,6);... SUBS(expandedHalfMessage,7);SUBS(expandedHalfMessage,8)]; % 1.6 define permutation function (PBOX) PBOX = @(halfMessage) halfMessage([16 7 20 21 29 12 28 17 ... 1 15 23 26 5 18 31 10 ... 2 8 24 14 32 27 3 9 ... 19 13 30 6 22 11 4 25]); % 1.7 define initial permutation (IP) IP = @(message) message([58 50 42 34 26 18 10 2 ... 60 52 44 36 28 20 12 4 ... 62 54 46 38 30 22 14 6 ... 64 56 48 40 32 24 16 8 ... 57 49 41 33 25 17 9 1 ... 59 51 43 35 27 19 11 3 ... 61 53 45 37 29 21 13 5 ... 63 55 47 39 31 23 15 7]); % 1.8 define final permutation (FP) FP = @(message) message([40 8 48 16 56 24 64 32 ... 39 7 47 15 55 23 63 31 ... 38 6 46 14 54 22 62 30 ... 37 5 45 13 53 21 61 29 ... 36 4 44 12 52 20 60 28 ... 35 3 43 11 51 19 59 27 ... 34 2 42 10 50 18 58 26 ... 33 1 41 9 49 17 57 25]); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% 2. key schedule %% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % 2.1 define permuted choice 1 (PC1) PC1L = @(key64) key64([57 49 41 33 25 17 9 ... 1 58 50 42 34 26 18 ... 10 2 59 51 43 35 27 ... 19 11 3 60 52 44 36]); PC1R = @(key64) key64([63 55 47 39 31 23 15 ... 7 62 54 46 38 30 22 ... 14 6 61 53 45 37 29 ... 21 13 5 28 20 12 4]); % 2.2 define permuted choice 2 (PC2) PC2 = @(key56) key56([14 17 11 24 1 5 3 28 ... 15 6 21 10 23 19 12 4 ... 26 8 16 7 27 20 13 2 ... 41 52 31 37 47 55 30 40 ... 51 45 33 48 44 49 39 56 ... 34 53 46 42 50 36 29 32]); % 2.3 define rotations in key-schedule (RK) % round# 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 RK = [1 1 2 2 2 2 2 2 1 2 2 2 2 2 2 1]; % 2.4 define key shift function (KS) KS = @(key28,s) [key28(s+1:end),key28(1:s)]; % 2.5 define sub-keys for each round leftHKey = PC1L(K); % 28-bit half key rightHKey = PC1R(K);% 28-bit half key for i = 1:16 leftHKey = KS(leftHKey,RK(i)); rightHKey = KS(rightHKey,RK(i)); key56 = [leftHKey ,rightHKey]; subKeys(i,:) = PC2(key56(:)); end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% 3. DES main loop %% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % 3.1 initial permutation C = IP(P); switch mode case 'ENC' % if encryption, split 64 message to two halves L{1} = HALF_L(C); % left-half 32-bit R{1} = HALF_R(C); % right-half 32-bit case 'DEC' % if decryption, swapping two halves L{1} = HALF_R(C); R{1} = HALF_L(C); end % 3.2 cipher round 1 to 16 for i = 1:16 L{i+1} = R{i}; % half key: 32-bit expended_R = EF(R{i}); % expended half key: 32-bit to 48-bit switch mode case 'ENC' % if encryption, apply sub-keys in the original order mixed_R = KM(expended_R,subKeys(i,:)); % mixed with sub-key: 48-bit case 'DEC' % if decryption, apply sub-keys in the reverse order mixed_R = KM(expended_R,subKeys(16-i+1,:)); % mixed with sub-key: 48-bit end substituted_R = SBOX(mixed_R); % substitution: 48-bit to 32-bit permuted_R = PBOX(reshape(substituted_R',1,32)); % permutation: 32-bit R{i+1} = xor(L{i},permuted_R); % Feistel function: 32-bit end % 3.3 final permutation switch mode case 'ENC' C = [L{end},R{end}]; case 'DEC' C = [R{end},L{end}]; end output64 = FP(C); varargout{1} = output64; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% END %% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%