vulcan-cryptanalysis

B
Vulcan Encrypt Simulation
%-----------------------------------------------------------
% Vulcan encryption simulation
% 2014-06-12 --- CJR
% inputs: 128-bit SRAM array contents "sram"
% 8-bit CV shift register contents "cv8"
% n-bit plaintext "pti"
% (31-bit ciphertext shift register contents "ctsr")
% outputs: n-bit ciphertext "cto"
% encrypts plaintext into ciphertext using Vulcan cipher
% requires "key schedule" to have been run prior to use
%-----------------------------------------------------------
% check user-supplied inputs for simple errors
if((exist(’sram’) == 0)||(length(sram) != 128))
error("128-bit SRAM array not found -- run key schedule")
end
if((exist(’cv8’) == 0)||(length(cv8) != 8))
error("8-bit CV shift register not found -- run key schedule")
end
if(exist(’pti’) == 0)
error("plaintext input not found -- create some plaintext")
end
if((exist(’ctsr’) == 0)||(length(ctsr) != 31))
ctsr = 1*(rand(1,31)>0.5); % create random initialization vector
end
% set up required variables
last = 0; % last plaintext output bit for differential encoder
cto = zeros(1,length(pti)); % pre-allocate ciphertext output
% process all bits of plaintext input
for ii = 1:length(pti)
% compute the XOR tree results
ct0 = pti(ii);
ct0 = bitxor(ct0,bitand(cv8(1),ctsr(22)));
ct0 = bitxor(ct0,bitand(cv8(2),ctsr(23)));
ct0 = bitxor(ct0,bitand(cv8(3),ctsr(24)));
ct0 = bitxor(ct0,bitand(cv8(4),ctsr(25)));
ct0 = bitxor(ct0,bitand(cv8(5),ctsr(26)));
ct0 = bitxor(ct0,bitand(cv8(6),ctsr(27)));
ct0 = bitxor(ct0,bitand(cv8(7),ctsr(28)));
ct0 = bitxor(ct0,bitand(cv8(8),ctsr(29)));
ct0 = bitxor(ct0,ctsr(30));
% differentially encode and save the output ciphertext bit
cto(ii) = last;
last = bitxor(ct0,last);
% compute the current SRAM address
addr = ctsr(1:7);
addr = addr*[1 2 4 8 16 32 64]’;
addr = addr+1;
% combine SRAM bit with CT21
keyb = sram(addr);
m0 = bitxor(ctsr(21),keyb);
% clock the ciphertext shift-register
ctsr = [ct0 ctsr(1:20) m0 ctsr(22:30)];
end
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