Question about sites with password to see images/galleries

[Dranishing]

I'm searching for websites where you can enter a password to see some images/galleries, I know someone who's uploading this codes but I really don't know where to introduce this codes.

This is an example of the codes that I had at the moment:
70vkmy
Gmrtu08
Cvmrry7
Qeldf3

From my understanding, those are codes to see nsfw/sfw images (the uploader sometimes tells references used for poses or themes of the image) I don't really know more, what I know is that.
1) You must introduce this codes somewhere.
2) Apparently those codes are for one to see images.
Anyway, help me out guys, I'm really curious about this.

 

[whowhawhy]

wouldn't those be url ids like an imgur album or url shortener links?

 

[Dranishing]

wouldn't those be url ids like an imgur album or url shortener links?

I tried before with imgur but it isn't, it might be some url shortener but I didn't tried in other websites besides imgur, I don't even know where else I can put that url shortener