digest program problem

Question

0 个投票

i use the following program to calculate a message digest for a message but i get error

??? Error: Expected a variable, function, or constant, found "incomplete string".

the program

%function hm = createdigest(m, varargin);
%A function which takes message string, m and creates a message digest
%using SHA-1, as described in federal publication FIPS 180-2.
%If the message is anything other than a binary string, use the 'convert'
%string. e.g. sha = createdigest('abc', 'convert')
%If dealing with binary strings, just call the script like this: 
%
%   sha = createdigest('011000010110001001100011');msgbox({'any random number must be less than',e},'take care');
x=inputdlg({'ENTER THE MESSAGE:'},'enter your message',1);
m=char(x);
maple('m:=',m);
%Initial Hash Values
    %Notation: H[word number](block number)  in a 32-bit binary string
    H00=dec2bin(hex2dec('67452301'),32);
    H10=dec2bin(hex2dec('efcdab89'),32);
    H20=dec2bin(hex2dec('98badcfe'),32);
    H30=dec2bin(hex2dec('10325476'),32);
    H40=dec2bin(hex2dec('c3d2e1f0'),32);
%Preprocessing
%1) Padding the message
      %convert message from a message string to a binary string
      s = '';
      if strcmp('convert', 'varargin')
          for a = 1:length(m),
              binstr = dec2bin(double(m(a)), 8);
              s=[s, binstr];
          end
      else 
          s = m;
      end
      %Pad binary string to be a multiple of 512 bits.  
      l = dec2bin(length(s),8);
      lstring = [int2str(zeros(64-length(l),1))' l];
      s = [s, '1', int2str(zeros(mod(448-length(s)-1,512),1))', lstring];
%2) Parsing the padded message
      %Padded message is subdivided into N 512-bit blocks 
      for n = 1:(length(s)/512),
          eval(['M' int2str(n) '= s(512*(n-1)+1:512*n) ;']);
      end
%Actual Hash Computation
      for n = 1:(length(s)/512),
          for t = 1:16,
              %First 15 32-bit words of the message schedule
              eval(['Wlog' sprintf('%d', (t-1)) ' = transpose(str2num(transpose(M' sprintf('%d', n) '(32*(t-1)+1:32*t))));']);
              eval(['W' sprintf('%d',(t-1)) ' = bin2dec(M' sprintf('%d', n) '(32*(t-1)+1:32*t));'])
          end
          for t = 16:79,
              eval(['Wlog' sprintf('%d',t) ' = transpose(circshift(transpose(bitxor(bitxor(bitxor(''Wlog' sprintf('%d',t-3) ',Wlog' sprintf('%d',t-8) '),Wlog' sprintf('%d',t-14) '),Wlog' sprintf('%d',t-16) ')), -1)) ;'])
              eval(['W' sprintf('%d',t) ' = bin2dec(transpose(int2str(transpose(Wlog' sprintf('%d', t) '))));'])
          end    
          %Initializing the five working string variables
          eval(['a=logical(transpose(str2num(transpose(H0' sprintf('%d', n-1) '))));']);
          eval(['b=logical(transpose(str2num(transpose(H1' sprintf('%d', n-1) '))));']);
          eval(['c=logical(transpose(str2num(transpose(H2' sprintf('%d', n-1) '))));']);
          eval(['d=logical(transpose(str2num(transpose(H3' sprintf('%d', n-1) '))));']);
          eval(['e=logical(transpose(str2num(transpose(H4' sprintf('%d', n-1) '))));']);
          for t = 0:79,
              %Setting up the schedule for function f and variable K
              if (t>=0 & t<=19), f = xor(and(b,c),and(not(b),d)); K=hex2dec('5a827999'); 
              elseif (t>=20 & t<=39), f = xor(xor(b,c),d); K=hex2dec('6ed9eba1');    
              elseif (t>=40 & t<=59), f = xor(xor(and(b,c),and(b,d)),and(c,d)); K=hex2dec('8f1bbcdc');
              elseif (t>=60 & t<=79), f = xor(xor(b,c),d); K=hex2dec('ca62c1d6');
              end    
              %Shifting the working variables according to the schedule
              T=sprintf('%d', [circshift(a(:),-5)';f;e]); 
              T=bin2dec(reshape(T, 3, 32));
              T=mod(T(1)+T(2)+T(3)+K, 2^32);
              eval(['T = mod(T + ' 'W' sprintf('%d', t) ', 2^32);']);
              T = logical(str2num(dec2bin(T, 32)')');
              e = d;
              d = c;
              c = circshift(b(:), -30)';
              b = a;
              a = T;
              %debug line
              %disp(t), disp(dec2hex(bin2dec(int2str(a')'),8)), disp( dec2hex(bin2dec(int2str(b')'),8)), disp( dec2hex(bin2dec(int2str(c')'),8)),  disp(dec2hex(bin2dec(int2str(d')'),8)), disp( dec2hex(bin2dec(int2str(e')'),8))
          end
          %Compute the immediate hash value
          eval(['H0' int2str(n) ' = dec2bin(mod(bin2dec(transpose(int2str(transpose(a)))) + bin2dec(num2str(H0' sprintf('%d', n-1) ')), 2^32), 32);' ]);
          eval(['H1' int2str(n) ' = dec2bin(mod(bin2dec(transpose(int2str(transpose(b)))) + bin2dec(num2str(H1' sprintf('%d', n-1) ')), 2^32), 32);' ]);
          eval(['H2' int2str(n) ' = dec2bin(mod(bin2dec(transpose(int2str(transpose(c)))) + bin2dec(num2str(H2' sprintf('%d', n-1) ')), 2^32), 32);' ]);
          eval(['H3' int2str(n) ' = dec2bin(mod(bin2dec(transpose(int2str(transpose(d)))) + bin2dec(num2str(H3' sprintf('%d', n-1) ')), 2^32), 32);' ]);
          eval(['H4' int2str(n) ' = dec2bin(mod(bin2dec(transpose(int2str(transpose(e)))) + bin2dec(num2str(H4' sprintf('%d', n-1) ')), 2^32), 32);' ]); 
      end
     blocknum=int2str(length(s)/512);
     eval(['sha = [H0' blocknum ' H1' blocknum ' H2' blocknum ' H3' blocknum ' H4' blocknum '];' ]);   
     hm = maple('convert', sha, 'decimal', 'binary');
%convert to hexadecimal for testing purposes
% H01 = dec2hex(bin2dec(H01))
% H11 = dec2hex(bin2dec(H11))
% H21 = dec2hex(bin2dec(H21))
% H31 = dec2hex(bin2dec(H31))
% H41 = dec2hex(bin2dec(H41))
%useful debug commands
%dec2hex(bin2dec(int2str(W15')'),8)

2 个评论
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Image Analyst 2012-2-17

Note: this code requires maple. (I copied, pasted, and ran it (despite the messed up formatting) and it complained about me not having maple.

Walter Roberson 2012-2-18

What a mess; what a senseless waste of eval()'s.

How about a clue about which line it complains about?

There is a line that looks problematic to me:

T = logical(str2num(dec2bin(T, 32)')');

This could potentially mean to use a quoted parenthesis rather than a conjugate transpose, end the argument, conjugate transpose the result of that expression.

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