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comparison m-toolbox/classes/+utils/@prog/hash.m @ 0:f0afece42f48

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author Daniele Nicolodi <nicolodi@science.unitn.it>
date Wed, 23 Nov 2011 19:22:13 +0100
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1 function h = hash(inp,meth)
2 % HASH - Convert an input variable into a message digest.
3 %
4 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
5 %
6 % HASH - Convert an input variable into a message digest using any of
7 % several common hash algorithms
8 %
9 % USAGE: h = hash(inp,'meth')
10 %
11 % inp = input variable, of any of the following classes:
12 % char, uint8, logical, double, single, int8, uint8,
13 % int16, uint16, int32, uint32, int64, uint64
14 % h = hash digest output, in hexadecimal notation
15 % meth = hash algorithm, which is one of the following:
16 % MD2, MD5, SHA-1, SHA-256, SHA-384, or SHA-512
17 %
18 % NOTES: (1) If the input is a string or uint8 variable, it is hashed
19 % as usual for a byte stream. Other classes are converted into
20 % their byte-stream values. In other words, the hash of the
21 % following will be identical:
22 % 'abc'
23 % uint8('abc')
24 % char([97 98 99])
25 % The hash of the follwing will be different from the above,
26 % because class "double" uses eight byte elements:
27 % double('abc')
28 % [97 98 99]
29 % You can avoid this issue by making sure that your inputs
30 % are strings or uint8 arrays.
31 % (2) The name of the hash algorithm may be specified in lowercase
32 % and/or without the hyphen, if desired. For example,
33 % h=hash('my text to hash','sha256');
34 % (3) Carefully tested, but no warranty. Use at your own risk.
35 % (4) Michael Kleder, Nov 2005
36 % (5) This is a direct copy of the code from Michael Kleder. Only
37 % the function name was changed to bring it in line with the
38 % LTPDA naming convention. (M Hewitson 15-09-07)
39 %
40 % EXAMPLE:
41 %
42 % algs={'MD2','MD5','SHA-1','SHA-256','SHA-384','SHA-512'};
43 % for n=1:6
44 % h=hash('my sample text',algs{n});
45 % disp([algs{n} ' (' num2str(length(h)*4) ' bits):'])
46 % disp(h)
47 % end
48 %
49 % NOTE: Original taken from MATHWORKS file exchange.
50 % Author: Michael Kleder, Nov 2005
51 % http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=8944&objectType=file
52 %
53 % $Id: hash.m,v 1.1 2008/06/18 13:35:11 hewitson Exp $
54 %
55 %
56
57 inp=inp(:);
58 % convert strings and logicals into uint8 format
59 if ischar(inp) || islogical(inp)
60 inp=uint8(inp);
61 else % convert everything else into uint8 format without loss of data
62 inp=typecast(inp,'uint8');
63 end
64
65 % verify hash method, with some syntactical forgiveness:
66 meth=upper(meth);
67 switch meth
68 case 'SHA1'
69 meth='SHA-1';
70 case 'SHA256'
71 meth='SHA-256';
72 case 'SHA384'
73 meth='SHA-384';
74 case 'SHA512'
75 meth='SHA-512';
76 otherwise
77 end
78 algs={'MD2','MD5','SHA-1','SHA-256','SHA-384','SHA-512'};
79 if isempty(strmatch(meth,algs,'exact'))
80 error(['Hash algorithm must be ' ...
81 'MD2, MD5, SHA-1, SHA-256, SHA-384, or SHA-512']);
82 end
83
84 % create hash
85 x=java.security.MessageDigest.getInstance(meth);
86 x.update(inp);
87 h=typecast(x.digest,'uint8');
88 h=dec2hex(h)';
89 if(size(h,1))==1 % remote possibility: all hash bytes < 128, so pad:
90 h=[repmat('0',[1 size(h,2)]);h];
91 end
92 h=lower(h(:)');
93 clear x
94 return