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Mohoshin
Mohoshin

Reputation: 19

Convert a string into hash value in matlab

How can I convert a message into a hash value using SHA/MD5 hashing in MATLAB? is there any builtin function or any fixed code?

Upvotes: 1

Views: 6693

Answers (3)

bliswell
bliswell

Reputation: 101

I just used this and it works well.

Works on strings, files, different data types. For a file I compared against CRC SHA through file explorer and got the same answer.

https://www.mathworks.com/matlabcentral/fileexchange/31272-datahash

Upvotes: 1

BartMan
BartMan

Reputation: 21

MATLAB's .NET classes appear to be a more recent creation than the JAVA hashing.
However, these classes don't have much/any public documentation available. After playing with it a bit, I found a way to specify one of several hash algorithms, as desired.

The "System.Security.Cryptography.HashAlgorithm" constructor accepts a hash algorithm name (string). Based on the string name you pass in, it returns different hasher classes (.SHA256Managed is only one type). See the example below for a complete string input ==> hash string output generation.

% Available options are 'SHA1', 'SHA256', 'SHA384', 'SHA512', 'MD5'
algorithm = 'SHA1';   

% SHA1 category
hasher = System.Security.Cryptography.HashAlgorithm.Create('SHA1');  % DEFAULT

% SHA2 category
hasher = System.Security.Cryptography.HashAlgorithm.Create('SHA256');  
hasher = System.Security.Cryptography.HashAlgorithm.Create('SHA384');  
hasher = System.Security.Cryptography.HashAlgorithm.Create('SHA512');

% SHA3 category:   Does not appear to be supported

% MD5 category
hasher = System.Security.Cryptography.HashAlgorithm.Create('MD5');

% GENERATING THE HASH:
str = 'Now is the time for all good men to come to the aid of their country';
hash_byte = hasher.ComputeHash( uint8(str) );  % System.Byte class
hash_uint8 = uint8( hash_byte );               % Array of uint8
hash_hex = dec2hex(hash_uint8);                % Array of 2-char hex codes

% Generate the hex codes as 1 long series of characters
hashStr = str([]);
nBytes = length(hash_hex);
for k=1:nBytes
    hashStr(end+1:end+2) = hash_hex(k,:);
end
fprintf(1, '\n\tThe %s hash is: "%s" [%d bytes]\n\n', algorithm, hashStr, nBytes);


% SIZE OF THE DIFFERENT HASHES:
%       SHA1:  20 bytes = 20 hex codes =  40 char hash string
%     SHA256:  32 bytes = 32 hex codes =  64 char hash string
%     SHA384:  48 bytes = 48 hex codes =  96 char hash string
%     SHA512:  64 bytes = 64 hex codes = 128 char hash string
%        MD5:  16 bytes = 16 hex codes =  32 char hash string

REFERENCES: 1) https://en.wikipedia.org/wiki/SHA-1 2) https://defuse.ca/checksums.htm#checksums

Upvotes: 2

casillas
casillas

Reputation: 16813

There are no functions in matlab to calculate hashes. However, you can call Java (any OS) or .Net (Windows only) functions directly from matlab and either of these implement what you want.

Note that you haven't specified the encoding of the string. The hash is different if you consider the string in ASCII, UTF8, UTF16, etc.

Also note that matlab does not have 160-bit or 256-bit integer, so the hash can't obviously be a single integer.

Anyway, using .Net:

SHA256

string = 'some string'; 
sha256hasher = System.Security.Cryptography.SHA256Managed;
sha256 = uint8(sha256hasher.ComputeHash(uint8(string)));
dec2hex(sha256)

SHA1

sha1hasher = System.Security.Cryptography.SHA1Managed;
sha1= uint8(sha1hasher.ComputeHash(uint8(string)));
dec2hex(sha1)

Java based solution can be found in the following link https://www.mathworks.com/matlabcentral/answers/45323-how-to-calculate-hash-sum-of-a-string-using-java

Upvotes: 4

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