A simple console lock authentication server simulation.

gen response steps:
1. take your CKB_S_CE_Key.pem and use rsapem2key.py to gen private_key and public_key
   $ python rsapem2key.py CKB_S_CE_Key.pem

2. replace private_key and public_key in folder keys/DEFAULT/

3. path in tool
   $ make

4. path in tool
   $ ./auth-server <challenge>

5. you will get <response>

6. type "ce" command in uboot console

7. copy <response> in input:

8. if <response> is valid, uboot console will unlock, and you can use any command in uboot console
