Unicode issue

[msmuenchen]

Hi,

I'm having problems using rusha for comparing a string in Javascript with the same string hashed in PHP.

In Javascript, I use

var sha=new Rusha(); sha.digest("\u00e4")
"7e5c0f7aba32cf3e22fd30c4513a21e6d1c3aeff"

and in PHP (once using a literal ä, once a json-decode'd ä to rule out a bug in PHP or my file encoding)

$c1="ä";
$c2=json_decode("\"\\u00e4\"");
echo "1: -$c1- 2: -$c2-\n";
echo json_encode($c1)."\n";
echo json_encode($c2)."\n";

echo sha1($c1)."\n";
echo sha1($c2)."\n";

which gives me the output

1: -ä- 2: -ä-
"\u00e4"
"\u00e4"
961fa22f61a56e19f3f5f8867901ac8cf5e6d11f
961fa22f61a56e19f3f5f8867901ac8cf5e6d11f

Why are the SHA1 hashes different? After all, using the \u00e4 notation should result in the same byte sequence both in a PHP string and a Javascript string, right?

[msmuenchen]

Found out the reason: JS strings are UTF16-stored, while PHP assumes multi-byte with UTF8. Fix is easy with the library at http://www.onicos.com/staff/iz/amuse/javascript/expert/utf.txt; I described the usage in http://stackoverflow.com/questions/19835609/differing-sha1-hashes-for-identical-values-on-the-server-and-the-client/21341088#21341088 where someone had a similar issue.

Might be worth to incorporate this conversion into the digest function?

[srijs]

Yes, it might be worth adding an encoding parameter to the digest method, which would be evaluated in the conversion function.

Would you like to make the change and submit a PR?

[msmuenchen]

I'm not that deep into JS, can you please do it?

[srijs]

I'm a bit short on time at the moment, but I'll see if I can get around to it sometime next week.

Anyway, thanks for pointing that out!

[stuartpb]

I'll submit a patch that runs unescape(encodeURIComponent(str)) on the string before interpreting it (this converts the string to its equivalent UTF-8 character codes).

[stuartpb]

Where exactly would I insert that? https://github.com/srijs/rusha/blob/master/rusha.js#L164 looks like a good candidate.

[srijs]

Hi.

Please modify rusha.sweet.js. A good candidate would be the rawDigest method. It could take an optional options parameter, where you can opt-in to the unescape(encodeURIComponent(str)) conversion.

[sergeevabc]

var r = new Rusha(); alert(r.digest("любовь"));

af48c12732ffdbd4299b792c2b6da6f77a0898d7 expected (works with jsSHA, CryptoJS, JSHash)
09c65cdd36ba4e6d767cde9acc71dfa75380655c rusha :(

Could be so kind and fix UTF8 issue at last?

[szydan]

@sergeevabc in case you still need it - from the documentation (readme)
"Create a hex digest from a binary String. A binary string is expected to only contain characters whose charCode < 256"

So the library will not work on arbitrary strings
The workaround I found for your case is to first convert your utf-8 encoded string to byte array and then pass it to rusha. See the code below:

function toUTF8Array(str) {
    var utf8 = [];
    for (var i=0; i < str.length; i++) {
        var charcode = str.charCodeAt(i);
        if (charcode < 0x80) utf8.push(charcode);
        else if (charcode < 0x800) {
            utf8.push(0xc0 | (charcode >> 6),
                      0x80 | (charcode & 0x3f));
        }
        else if (charcode < 0xd800 || charcode >= 0xe000) {
            utf8.push(0xe0 | (charcode >> 12),
                      0x80 | ((charcode>>6) & 0x3f),
                      0x80 | (charcode & 0x3f));
        }
        // surrogate pair
        else {
            i++;
            // UTF-16 encodes 0x10000-0x10FFFF by
            // subtracting 0x10000 and splitting the
            // 20 bits of 0x0-0xFFFFF into two halves
            charcode = 0x10000 + (((charcode & 0x3ff)<<10)
                      | (str.charCodeAt(i) & 0x3ff));
            utf8.push(0xf0 | (charcode >>18),
                      0x80 | ((charcode>>12) & 0x3f),
                      0x80 | ((charcode>>6) & 0x3f),
                      0x80 | (charcode & 0x3f));
        }
    }
    return utf8;
}

var r = new Rusha();
var s = "любовь"
var a = toUTF8Array(s)
console.log(r.digest(a));  //will give you the correct sha1 af48c12732ffdbd4299b792c2b6da6f77a0898d7

[sergeevabc]

Thanks for your input, @szydan. At that time I chose Fast SHA256.

[srijs]

Closing this as wontfix -- Rusha is not meant to be used directly on encoded strings with code-points above 255. If you want to hash strings like these, please be sure to convert them into the desired binary encoding beforehand.