Litmus paper - turning red, blue and even bleached I have blue litmus paper, and if I put it in an acid it turns red. I also have red litmus paper, and if I put it in a base, it turns blue.
I know the question about litmus was asked and answered and I like the answer:
How does the litmus pH indicator work? 
However, damp litmus paper also becomes bleached in presence of chlorine gas. I believe it has nothing to do with the mechanism described in aforementioned question. I wonder what the mechanism is. Wikipedia actually suggests:


  For instance, chlorine gas turns blue litmus paper white – the litmus dye is bleached, because of presence of hypochlorite ions. This reaction is irreversible, so the litmus is not acting as an indicator in this situation.


I also found an equation which describes formation of hypochloric acid (source): 
$$\ce{Cl2 (g) + H2O (l) -&gt; HClO (aq) + HCl (aq)}$$

The problem that I have now is as follows: We know that litmus paper gets discolored because of contact with hypochloric acid. But what is actually the chemical reaction for that?
I can supply some details now, and hopefully this ought to qualify as an answer.

As I mentioned earlier litmus is a mixture of 10-12 dyes (CAS number: 1393-92-6).

The acid-base indicator properties of litmus are primarily due to 7-hydroxyphenoxazone chromophore (pictured below)


The answer you linked to discusses the acid-base indication mechanism in some detail, so I shall skip over that. 

Anyway, what this serves to establishing that it is indeed a extended $\pi$-conjugated system that we are dealing with in the chromophore. 

Now, $\ce{HOCl}$ would bring about halohydrination (basically an electrophilic addition) across the $\pi$ bonds, thus disrupting the conjugated system. 

Halohydrins are compounds that contain an $\ce{-OH}$ and $\ce{-X}$ groups on adjacent carbons. 

This image describes the general mechanistic scheme in a simpler case: 


Anyway, after said addition reaction has taken place in the chromophore, the $\pi$-conjugated system is disrupted, and thus, we see an absence of colour.