vulcan-cryptanalysis

];
% differentially decode the ciphertext prior to processing
ctd = abs(diff(ct));
% set up initial conditions
solved = 0; % no solution
outernotdone = 1; % loop flag
ii = 1; % CV shift register table index
while(outernotdone)
% get 8-bit CV shift register candidate from table & convert to binary
v = dec2bin(cs(ii),8);
cv8 = toascii(v)-48;
% set up new blank solution
qqq = zeros(64,65); % augmented solution matrix
rrr = zeros(64,1); % vector of matrix rows that have been filled
innernotdone = 1;
nn = 32; % index of ciphertext bit
while(innernotdone)
% form SRAM addresses
a1 = ctd(nn-8:nn-2)*[64 32 16 8 4 2 1]’;
a2 = ctd(nn-9:nn-3)*[64 32 16 8 4 2 1]’;
a3 = ctd(nn-10:nn-4)*[64 32 16 8 4 2 1]’;
a4 = ctd(nn-11:nn-5)*[64 32 16 8 4 2 1]’;
a5 = ctd(nn-12:nn-6)*[64 32 16 8 4 2 1]’;
a6 = ctd(nn-13:nn-7)*[64 32 16 8 4 2 1]’;
a7 = ctd(nn-14:nn-8)*[64 32 16 8 4 2 1]’;
a8 = ctd(nn-15:nn-9)*[64 32 16 8 4 2 1]’;
a9 = ctd(nn-16:nn-10)*[64 32 16 8 4 2 1]’;
% get SRAM content vectors
v1 = sr(a1+1,:);
v2 = sr(a2+1,:);
v3 = sr(a3+1,:);
v4 = sr(a4+1,:);
v5 = sr(a5+1,:);
v6 = sr(a6+1,:);
v7 = sr(a7+1,:);
v8 = sr(a8+1,:);
v9 = sr(a9+1,:);
% build left side of linear equation describing this ciphertext bit
vv = zeros(1,64);
vv = bitxor(vv,bitand(cv8(1),v1));
vv = bitxor(vv,bitand(cv8(2),v2));
vv = bitxor(vv,bitand(cv8(3),v3));
vv = bitxor(vv,bitand(cv8(4),v4));
vv = bitxor(vv,bitand(cv8(5),v5));
vv = bitxor(vv,bitand(cv8(6),v6));
vv = bitxor(vv,bitand(cv8(7),v7));
vv = bitxor(vv,bitand(cv8(8),v8));
vv = bitxor(vv,v9);
% build right side of linear equation describing this ciphertext bit
% i.e. calculate resulting keystream bit (assuming plaintext was 0)
c = ctd(nn); % (if plaintext was NOT 0, XOR the known plaintext bit here)
c = bitxor(c,bitand(cv8(1),ctd(nn-22)));
c = bitxor(c,bitand(cv8(2),ctd(nn-23)));
c = bitxor(c,bitand(cv8(3),ctd(nn-24)));
c = bitxor(c,bitand(cv8(4),ctd(nn-25)));
c = bitxor(c,bitand(cv8(5),ctd(nn-26)));
c = bitxor(c,bitand(cv8(6),ctd(nn-27)));
40