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1 function h = hash(inp,meth)
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2 % HASH - Convert an input variable into a message digest using any of
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3 % several common hash algorithms
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4 %
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5 % USAGE: h = hash(inp,'meth')
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6 %
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7 % inp = input variable, of any of the following classes:
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8 % char, uint8, logical, double, single, int8, uint8,
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9 % int16, uint16, int32, uint32, int64, uint64
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10 % h = hash digest output, in hexadecimal notation
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11 % meth = hash algorithm, which is one of the following:
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12 % MD2, MD5, SHA-1, SHA-256, SHA-384, or SHA-512
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13 %
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14 % NOTES: (1) If the input is a string or uint8 variable, it is hashed
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15 % as usual for a byte stream. Other classes are converted into
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16 % their byte-stream values. In other words, the hash of the
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17 % following will be identical:
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18 % 'abc'
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19 % uint8('abc')
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20 % char([97 98 99])
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21 % The hash of the follwing will be different from the above,
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22 % because class "double" uses eight byte elements:
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23 % double('abc')
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24 % [97 98 99]
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25 % You can avoid this issue by making sure that your inputs
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26 % are strings or uint8 arrays.
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27 % (2) The name of the hash algorithm may be specified in lowercase
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28 % and/or without the hyphen, if desired. For example,
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29 % h=hash('my text to hash','sha256');
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30 % (3) Carefully tested, but no warranty. Use at your own risk.
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31 % (4) Michael Kleder, Nov 2005
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32 %
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33 % EXAMPLE:
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34 %
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35 % algs={'MD2','MD5','SHA-1','SHA-256','SHA-384','SHA-512'};
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36 % for n=1:6
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37 % h=hash('my sample text',algs{n});
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38 % disp([algs{n} ' (' num2str(length(h)*4) ' bits):'])
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39 % disp(h)
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40 % end
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41
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42 inp=inp(:);
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43 % convert strings and logicals into uint8 format
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44 if ischar(inp) || islogical(inp)
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45 inp=uint8(inp);
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46 else % convert everything else into uint8 format without loss of data
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47 inp=typecast(inp,'uint8');
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48 end
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49
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50 % verify hash method, with some syntactical forgiveness:
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51 meth=upper(meth);
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52 switch meth
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53 case 'SHA1'
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54 meth='SHA-1';
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55 case 'SHA256'
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56 meth='SHA-256';
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57 case 'SHA384'
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58 meth='SHA-384';
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59 case 'SHA512'
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60 meth='SHA-512';
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61 otherwise
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62 end
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63 algs={'MD2','MD5','SHA-1','SHA-256','SHA-384','SHA-512'};
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64 if isempty(strmatch(meth,algs,'exact'))
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65 error(['Hash algorithm must be ' ...
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66 'MD2, MD5, SHA-1, SHA-256, SHA-384, or SHA-512']);
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67 end
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68
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69 % create hash
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70 x=java.security.MessageDigest.getInstance(meth);
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71 x.update(inp);
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72 h=typecast(x.digest,'uint8');
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73 h=dec2hex(h)';
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74 if(size(h,1))==1 % remote possibility: all hash bytes < 128, so pad:
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75 h=[repmat('0',[1 size(h,2)]);h];
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76 end
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77 h=lower(h(:)');
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78 clear x
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79 return |
