[#395238] rubygem: ispunity (unite all your internet connections) — Arun Tomar <tomar.arun@...>

Dear friends,

12 messages 2012/05/01

[#395250] Overwriting one Ruby array or arrays with another — Craig Law <lists@...>

Hi

14 messages 2012/05/02

[#395258] array of strings - finding letter combinations — "Sebastjan H." <lists@...>

Hi All,

16 messages 2012/05/02

[#395357] Why Enumerator#next does not return more than one value? — Földes László <lists@...>

If I have an Enumerator which yields elements of a mathematical series

10 messages 2012/05/07

[#395373] How to use Data_Wrap_Struct to assign the DATA VALUE to an exsiting Ruby object? — Iñaki Baz Castillo <ibc@...>

Hi, my code receives an arbitrary klass name (provided by the user)

8 messages 2012/05/07

[#395429] passing via instance variable or regular () — sam jam <lists@...>

def first

10 messages 2012/05/10

[#395463] I'm looking for a Metaprogramming Project — Phil Stone <lists@...>

Hello,

19 messages 2012/05/11

[#395548] A million reasons why Encoding was a mistake — Marc Heiler <lists@...>

Newcomer wants to try Ruby.

15 messages 2012/05/15
[#395561] Re: A million reasons why Encoding was a mistake — Ryan Davis <ryand-ruby@...> 2012/05/15

[#395595] Re: A million reasons why Encoding was a mistake — Brian Candler <lists@...> 2012/05/16

I will add that the OP is not entirely alone in his opinion.

[#395551] How to ensure that a block runs entirely after other threads? (Thread.exclusive does not "work") — Iñaki Baz Castillo <ibc@...>

Hi, I expected that in the following example code, thread t1 would not

8 messages 2012/05/15

[#395575] GUI with ruby on windows — David Acosta <lists@...>

hello friends, i am a begginer and i have a litlle question, how can i

17 messages 2012/05/16

[#395604] what is going wrong here? — roob noob <lists@...>

Notice the initialization of both classes in each of the examples, if

20 messages 2012/05/16

[#395646] rb_gc_register_address() or rb_gc_mark()? — Iñaki Baz Castillo <ibc@...>

Hi, I've bad experiences with rb_gc_register_address(), it does never

16 messages 2012/05/17

[#395686] reading from and writing to a Unicode encoded file — "Sebastjan H." <lists@...>

Hi,

19 messages 2012/05/18
[#395694] Re: reading from and writing to a Unicode encoded file — Regis d'Aubarede <lists@...> 2012/05/18

Hello,

[#395697] Re: reading from and writing to a Unicode encoded file — "Sebastjan H." <lists@...> 2012/05/18

Regis d'Aubarede wrote in post #1061272:

[#395698] Re: reading from and writing to a Unicode encoded file — Regis d'Aubarede <lists@...> 2012/05/18

Sebastjan H. wrote in post #1061276:

[#395699] Re: reading from and writing to a Unicode encoded file — "Sebastjan H." <lists@...> 2012/05/18

Regis d'Aubarede wrote in post #1061277:

[#395750] Re: reading from and writing to a Unicode encoded file - issues when using Shoes — "Sebastjan H." <lists@...> 2012/05/21

Hi,

[#395754] Re: reading from and writing to a Unicode encoded file - issues when using Shoes — "Sebastjan H." <lists@...> 2012/05/21

Sebastjan H. wrote in post #1061483:

[#395740] ? Ruby through CGI and Rails — Shaun Lloyd <list@...>

Hi everybody,

22 messages 2012/05/21
[#395764] Re: Ruby through CGI and Rails — Brian Candler <lists@...> 2012/05/21

Shaun Lloyd wrote in post #1061455:

[#395786] Re: Ruby through CGI and Rails — Shaun Lloyd <list@...> 2012/05/22

On 22/05/12 03:37, Brian Candler wrote:

[#395838] Re: Ruby through CGI and Rails — Brian Candler <lists@...> 2012/05/23

Shaun Lloyd wrote in post #1061602:

[#395787] Changing self class from inside a method?? — David Madison <lists@...>

Let's start off with the assumption I want a method that allows an

10 messages 2012/05/22

[#395841] Memory-efficient set of Fixnums — George Dupre <lists@...>

Hi,

25 messages 2012/05/23

[#395883] looking for a ruby idiom : r=foo; return r if r — botp <botpena@...>

Hi All,

11 messages 2012/05/24

[#395966] Am I justified to use a global variable if it must be used in all scopes? — Phil Stone <lists@...>

Hello,

12 messages 2012/05/27

[#396010] does this leak more than the size of the string via timing side channels — rooby shoez <lists@...>

string1 = "string"

16 messages 2012/05/29

[#396038] Is it possible to avoid longjmp in exceptions, Thread#kill, exit(), signals? — Iñaki Baz Castillo <ibc@...>

Hi, my Ruby C extension runs a C loop (libuv) without GVL. At some

8 messages 2012/05/29

Re: does this leak more than the size of the string via timing side channels

From: Martin Bo煬et <martin.bosslet@...>
Date: 2012-05-29 09:09:26 UTC
List: ruby-talk #396023
2012/5/29 rooby shoez <lists@ruby-forum.com>:
> Thanks for the advice I will probably go with your technique Martin. I
> am considering using your technique as well as the original solution I
> inquired about. I have a question though, will it work to compare every
> character or will it also return false as soon as it detects that one is
> not = ?

I'm not sure I fully understand, where exactly in your code would that be?

> def message_authentic?(ciphertext, key, mac)
>
> computed_mac =
> OpenSSL::Digest::SHA256.new(OpenSSL::HMAC.digest(OpenSSL::Digest::SHA256.new,OpenSSL::Digest::SHA256.new("mac"
> + key).to_s, ciphertext))
>
> provided_mac = OpenSSL::Digest::SHA256.new(mac)
> comparisons = [true]
> computed_mac.length.times do |i|
> a += [string1[i] == string2[i]]
> end
> comparisons.inject(:==)
> end
>
> Is it at all beneficial to add the second way of comparison as well or
> is it just as protected with == after the hash values have been
> obtained? And you are pretty confident that this is no vulnerable to
> timing side channels ?

Yes, it was also recommended by Dan Boneh during his online
cryptography course, and he can be trusted :)
The comparison of the hashes can be done using plain ==, as there's
nothing to be gained from timing this comparison. Even if you figure
out the hashes by timing them, it's not possible to get to the original
value from there.
Then again computing the hash itself from the original value is also not
vulnerable because the algorithm for the hash will always take the same
time as it ideally doesn't care about its underlying input and won't take
different code paths for different inputs.


-Martin

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