What the SHA-1 is MAC iButton

Hi,

I just purchased a DS1961S iButton EEPROM. Seemed to be pretty straightforward until I started to write the code. Reading is standard 1-wire, but to write from the scratchpad to the EEPROM memory you have to perform a "SHA-1 Algorithm" which generates a 160-bit MAC which is needed to start the transfer.

Has anyone seen this or worked with it or even understand it.

Please help

Chris

Don't worry folks,

I am just going to take this super secure animal back where it came from and get a standard iButton EEPROM like the DS1973 which doesn't need all that calculation just to write a byte of data.

Still, if anyone really wants super security, here is your answer!

Regards

Chris

I have to make the sha-1 implementation on pic18f452, can help me anyone??
sorry for do the question on this post.