Protect-Me is a C application which allows you to protect your PSP with a password.

To install it, run the PBP inclued with your PSP (to set the password) and then put the prx (password.prx) in ms:0/seplugins and activate it via the recovery menu… And now it will ask you a password at each XMB boot. You can change the password with launching the EBOOT.PBP which you ran to install the pass…

http://forums.qj.net/f-psp-development-forum-11/t-protect-me-v10-129505.html