How to calculate hash sum of a string (using java)?

Question

Sebastian Holmqvist 2012-8-6

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/45323-how-to-calculate-hash-sum-of-a-string-using-java

回答： Oliver Woodford 2016-5-5

Couldn't find this very easily (without including a bunch of c-mex files etc) so I thought I'd post it here for future reference. I prefer using java methods to avoid dependencies.

Question:

Using java, how to create a MD5 (or SHA1 etc) hash sum of a string?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Sebastian Holmqvist 2012-8-6

3
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/45323-how-to-calculate-hash-sum-of-a-string-using-java#answer_55484

编辑：Sebastian Holmqvist 2012-8-6

在 MATLAB Online 中打开

Solution:

The trick here is to input an ascii representation of your string (hence, the double(string) call). MessageDigest outputs 16 bytes which represents 32 chars. So we use BigInteger to convert the bytes to that radix.

import java.security.*;
import java.math.*;
md = MessageDigest.getInstance('MD5');
hash = md.digest(double('Your string.'));
bi = BigInteger(1, hash);
char(bi.toString(16))
ans = 
b99e5935368933bafefed10b99bb0489

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Nick Hilton 2015-10-14

在 MATLAB Online 中打开

I found a bug, BigInteger.toString(16) won't fill with zeros. For example, if the BigInter's hex representation was '0abc', toString(16) will only return 'abc'.

Fixing this requires using the java.lang.String.format method:

import java.lang.String;
char(String.format('%032x', bi));

MD5 returns 32 hex values, but if one were to change the message digest to 'SHA-256', then one needs to use:

char(String.format('%064x', bi));

This will guarantee a fixed width hash filled with '0'.

请先登录，再进行评论。

Answer 2

Oliver Woodford 2016-5-5

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/45323-how-to-calculate-hash-sum-of-a-string-using-java#answer_220897

在 MATLAB Online 中打开

A similar solution:

%STRING2HASH Convert a string to a 64 char hex hash string (256 bit hash)
%
%   hash = string2hash(string)
%
%IN:
%   string - a string!
%
%OUT:
%   hash - a 64 character string, encoding the 256 bit SHA hash of string
%          in hexadecimal. 
function hash = string2hash(string)
persistent md
if isempty(md)
    md = java.security.MessageDigest.getInstance('SHA-256');
end
hash = sprintf('%2.2x', typecast(md.digest(uint8(string)), 'uint8')');
end