Inside Windows Product Activation
Decoding
The mapping between the Product ID in decimal representation and its binary encoding in the double words P1 and P2 and the byte P3 is summarized in the following table.
digits | length | encoding |
|---|---|---|
| ||
AAAAA | 17 bits | bit 0 to bit 16 of P1 |
BBB | 10 bits | bit 17 to bit 26 of P1 |
CCCCCCC | 28 bits | bit 27 to bit 31 of P1 (lower 5 bits) |
bit 0 to bit 22 of P2 (upper 23 bits) | ||
DDEEE | 17 bits | bit 23 to bit 31 of P2 (lower 9 bits) |
bit 0 to bit 7 of P3 (upper 8 bits) |
digits | meaning |
|---|---|
| |
AAAAA | apparently always 55034 (in Windows XP RC1) |
BBB | most significant three digits of Raw Product Key |
CCCCCCC | least significant six digits of Raw Product Key plus check digit |
DD | index of the public key used to verify the Product Key |
EEE | random value |
As can be seen, the (Raw) Product Key plays an important role in generating the Product ID.