I'm following this tutorial: [Raspberry Pi - SSH Public Key Authentication](http://www.codeproject.com/Tips/600050/Raspberry-Pi-SSH-Public-Key-Authentication), but I'm generating the keys directly on my Raspberry.

So this is exactly what I did:

start a fresh Raspbian image

    ssh-keygen -t rsa -C "my_name"

Saved at default folder `/home/pi/.ssh`

Copied the public key `id_rsa.pub` to `/home/pi/.ssh/authorized_keys`
using the command:

    cd /home/pi/.ssh
    mkdir authorized_keys
    cp id_rsa.pub authorized_keys/

so then I've gone to `authorized_keys` with 

    cp authorized_keys

and there was my public key in the format 

    ssh-rsa big_string_here my_name

then I copied the private key to my pen drive using

    cp id_rsa /media/PENDRIVE

Opened puttygen, gone to Conversions, imported the key from my pen drive, saved the private key also in my pen drive, then opened Putty and started a connection to my Raspberry Pi. It asks me to type the user I want to connect, I type `pi` and then the terminal writes this:

> "server refused our key"


And gives the error:

> Disconnected: No supported authentication methods available (server sent: public key)

I've already formatted my Pi 3 times and tried this with a fresh installation, but I'm getting these errors.

Could someone help me?


UPDATE:
    
When I try to log from the same raspberry pi, it says: Permission denied (public key).
When I see the permissions of the file `id_rsa.pub` inside `authorized_keys` I get:

    -rw-r--r-- 1 root root 387 Fevb 16 14:06 id_rsa.pub
    
is everything alright?


Update 2:
   
It looks like that `authorized_keys` is a file not a directory. 
So I changed it to a file and now there are the permissions:

    
    -rw------- 1 root root 387 Apr 25 18:44 authorized_keys
    -rw------- 1 pi pi 1766 ... id_rsa
    -rw-r--r-- 1 root root 387 ... ida_rsa.pub
    
I think `authorized_keys` must be owned by `pi`, also?

UPDATE 3:

Changed group and user to `pi` and it worked. Thank you all.