DM2016 Data sheet

V2.2

Sep 04,2008

5

6、 FUNCTION DESCRIPTION

6.1 I

2

C

DM2016 has an I

2

C salve device interface,there are two I

2

C device addresses can be selected

through controlling the external port.The high 6-bit of I2C address is “101000”,so the I

2

C device

address can be selected with 0xA0，0xA2.

I

2

C data address space assignment:

Address

Description

0x00-0x7F

EEPROM

0x80-0x8F

128 bit secret key

0x90-0x97

64 bit plain code and encrypted code

The most signification byte of 128 bit secret key is stored in address “0x80”; The least

signification byte of 128 bit secret key is stored in address “0x8F”.

The most signification byte of 64 bit plain code or encrypted code is stored in address

“0x90”,the least signification byte of 64 bit plain code or encrypted code is stored in

address“0x97”.When reading,the data is plain code.When writing,the data is encrypted code.

6.2 Decryption Function

DM2016 is a security chip to prevent from copying. It can effectively protect software

design through a decryption arithmetic and the relative 128 bit secret key. The 128 bit secret

keys are stored in OTP memory.

The authentication process of DM2016 is as below:

A group of 64bit random data generated by program acts as plain code. Program executes the

encryption arithmetic by utilizing the plain code and the same secret key in 128 bit OTP memory,

and generates a group of encrypted code. Then program sends the encrypted code to DM2016 through

I

2

C interface.DM2016 executes the decryption arithmetic with 128 bit secret key and 64 bit

encrypted code, then generates a group of 64 bit plain code. Program reads back the plain code

through I

2

C interface, then compares the plain code with the original plain code(64bit random

data).If the two values are equal, it will declare that the authentication pass and the program

will continue to execute. Otherwise, the program will exit.