Hello. In my app I send emails to tell that the user has certificate and
I
want to put a link - Unsubscribe. I don’t know how to construct this
link
so that there won’t be users that unsubscribe other users. I mean I want
to
make that is safe. I look in the web for how these unsubscribe links are
made but I couldn’t find anything. Can someone help me? Thanks in
advance
You should look at Devise gem Token Authenticatable solution as example.
You just add “?auth_token=#{@user.auth_token}” to your unsubsribe url.
, 22 2012 ., 15:06:58 UTC+4 Tsvetelina
Borisova :
Thanks for the quick response 
22 2012, , 15:14:13 UTC+3, :
Andrei’s solution works because with Device gem the User#auth_token is
randomly generated and unique per your app. It would be extremely hard
to
brute-force it, that’s why it’s safe; though it would be a good idea to
make sure you deny 4th or whichever unsuccessful try to use the same
action
in the same context (i.e. relating to the same user; similarly to that
when
you get your account locked if you enter PIN 3 times unsuccessfully) if
you
are expecting to be brute-forced or simply have higher security level
required by the client or yourself.
The basic principle could be seen put into practice all over the
security-related fields: make it harder to brute force it than the data
that the “offender” tries to get hold of is worth.
2012/7/22 Tsvetelina B. [email protected]
Thanks I was looking exactly for answer like yours - Andrei’s answer is
cool and I only needed more theory on these unsubscribe links. Thanks
Dihital
22 2012, , 17:41:54 UTC+3, Dihital :
Sure! Glad to have helped somewhat. It’s a perception thing (at least it
is
for me). I mean a string of 10 symbols of hexadecimal characters
(0-through-f) could have 16^10 outcomes (= over 1 trillion = 100
billions).
So just a single random guess (like buying lottery ticket) would give
you a
1 in / 1110 000 000 chance to hit it.
Most random ID generators (or however they are called) uses 20 or 22
symbols. So the chance to “guess it” goes to “insanely unlikely”.
2012/7/22 Tsvetelina B. [email protected]
I just want to make it explicit, that I’ve made quite a few errors in
numbers because of poor editing. Still it stays at billions even for a
10-character hexadicamal (gmail says to put ‘sp’ here ;)). I myself
realized the unlikeliness of a conflict by using GIT. I mean if GIT is
good
enough for keeping thousands of revisions by this system, then the
system
is fine, but as I said you could always take extra precautions, the
degree
of those depending on your needs: I mean you could make an app that
requires each step to be confirmed by an administrator… I think you
see
where I am going with this: it’s either pure math or you monitoring
stuff
personally for an extra 0.000001% better. I’d turn to math and
statistics
in such a case that you described.
BTW is anyone disagreeing with me? I hope so, then please write to this
thread so we can come to an optimal solution (or as close as we could
get
to it in a general case we are talking about).
2012/7/22 Gintautas Šimkus [email protected]