DeviceID

On PS Vita, the Device ID is a unique 20-bytes hexadecimal sequence. It is simply the SHA1 hash of the OpenPSID. It is stored inside several files such as id.dat or calendar.db in order to check that the inserted memory card was not previously in another PS Vita, else a database refresh is performed.

Why did SCE not simply use the OpenPSID?

On PSP, OpenPSID was almost never used except for savedata.

On PS3, OpenPSID was used for act.dat checks, savedata / trophies when no PSN account bounded.

On PS Vita, OpenPSID is used the same way as on PS3 but SCE secured still more its console by using the hash of OpenPSID and not OpenPSID itself.

This way, it is harder for people to know their openPSID. But since we have tm0: partition read access with exploits, we can simply read 0x10 Bytes at offset 0x850 of tm0:npdrm/act.dat to get openPSID.

 ux0:id.dat

Location of the files where it is stored

ux0:calendar/calendar.db

File	Value	Info
id.dat	DID=297C4C0FA1F5A6E374FE4FE65535E03DC1643F2C
calendar.db	tbl_app_authentication_info >> column open_psid >> 297C4C0FA1F5A6E374FE4FE65535E03DC1643F2C	The value is stored as an ASCII text.

Structure

Name	length	Example
DID	20 bytes (0x14)	297C4C0FA1F5A6E374FE4FE65535E03DC1643F2C