HS algo verification should use constant time comparison

[davedoesdev]

https://github.com/kjur/jsjws/blob/master/jws-3.0.js#L505

to prevent timing attacks.

[davedoesdev]

@kjur looks like this is still present in jsrsasign?

https://github.com/kjur/jsrsasign/blob/master/src/jws-3.3.js#L484

[kjur]

Hi, how can I fix this?

[davedoesdev]

Hi @kjur - what about something like this?

// from https://github.com/goinstant/buffer-equal-constant-time/blob/master/index.js
var const_time_equal = function (s1, s2)
{
    "use strict";
    if (s1.length !== s2.length)
    {
        return false;
    }
    var i, c = 0;
    for (i = 0; i < s1.length; i += 1)
    {
        /*jslint bitwise: true */
        c |= s1.charCodeAt(i) ^ s2.charCodeAt(i); // XOR
        /*jslint bitwise: false */
    }
    return c === 0;
};

[davedoesdev]

Closed in favour of kjur/jsrsasign#309