Erlang和JavaScript MD5 Digest匹配 [英] Erlang and JavaScript MD5 Digest match

问题描述

在此测试MD5的Javascript实现： http://www.webtoolkit.info/javascript-md5.html 给出以下输出：

Testing the Javascript Implementation of MD5 here: http://www.webtoolkit.info/javascript-md5.html gives the following output:

MD5("muzaaya") = "00e081abefbbbf72b2d5258196a9b6d0"

去我的erlang shell，并计算相同值的MD5，我得到这个：

Going to my erlang shell, and calculating the MD5 of the same value i get this:

Eshell V5.8.4  (abort with ^G)
1> erlang:md5("muzaaya").
<<0,224,129,171,239,187,191,114,178,213,37,129,150,169,
  182,208>>
2>

我如何比较两个？如果JavaScript前端应用程序的MD5结果来到我的Erlang后端，我想要比较两个Digest。我如何将Javascript MD5摘要与Erlang的摘要相匹配？

How can i compare the two? If the MD5 result from the JavaScript front end app comes to my Erlang backend, i would like to be able to compare the two Digests. How can i match the Javascript MD5 digest to that of Erlang?

推荐答案

MD5哈希本质上是一个128位的数字。

And MD5 hash is in essence a 128-bit number.

您将Erlang中的MD5值作为16个字符（16 * 8 = 128）的二进制格式收到。该二进制文件中的每个数字都必须转换为十六进制，以与JavaScript的MD5输出（这是一个十六进制字符串）相当：

You receive the MD5 value in Erlang as a binary of 16 characters (16 * 8 = 128). Each number in that binary has to be converted into hexadecimal to be comparable to JavaScript's MD5 output (which is a hexadecimal string):

2> lists:flatten([io_lib:format("~2.16.0b", [B]) || <<B>> <= MD5]).
"00e081abefbbbf72b2d5258196a9b6d0"

首先，我们从二进制文件中取出每个字节，并使用 io_lib 模块将其格式化为十六进制字符串。然后，我们使用flatten函数将其显示为可读字符串（尽管如果要将值写入文件或套接字，这是不必要的，因为它们能够处理深io列表，嵌套的字符列表或二进制文件）

First, we take each byte from the binary and use the io_lib module to format it to a hexadecimal string. Then we use the flatten function to display it as a readable string (although this isn't necessary if you're going to write the value to a file or a socket since they are able to handle deep io lists, nested lists of characters or binaries).

使用的格式字符串〜2.16.0b 表示格式化整数（ b ）使用基础 16 和填充宽度 2 与填充字符 0 。

The format string used, ~2.16.0b means format an integer (b) using base 16 and padding to width 2 with the padding character 0.

如果你想要一个二进制文件，你可以使用以下二进制理解：

If you want a binary, you could use the following binary comprehension:

3> << << (list_to_binary(io_lib:format("~2.16.0b", [C])))/binary >>
     || <<C>> <= MD5 >>.
<<"00e081abefbbbf72b2d5258196a9b6d0">>

（而不是 io_lib：format / 2 还有 http_util：integer_to_hexlist / 1 ，虽然我不知道它是否更快）

(Instead of io_lib:format/2 there is also http_util:integer_to_hexlist/1, although I don't know if it is faster)

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