Can anybody help me with ATSHA204A interface?

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Harikrishnan911
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Joined: Fri. Sep 9, 2016
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Location: Kerala, India
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Posted by Harikrishnan911: Sat. Mar 10, 2018 - 09:30 AM
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Hi,

 

i am a newbie in this domain & i am facing this challenge to store data in ATSHA204A internal EEPROM with encryption enabled.

I have gone through the datasheet but didn't really understand with all those facts & info. I really need a helping hand here.

I have managed to wake up the crypto IC & was able to communicate with it.

Can this IC perform multiple read write to its EEPROM with causing any issues?

The Zone encoding pose another hurdle in this process.

Can somebody help me with this?

 

Thanks & Regards,

Silly beans are always silly
:)

Tags:

Security, General Security Discussions, #atsha204a, #SAMD21, Lighting Control
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PhillyNJ
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Joined: Sat. Oct 11, 2014
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Posted by PhillyNJ: Sat. Oct 27, 2018 - 11:18 PM
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Harikrishnan911 wrote:
Can this IC perform multiple read write to its EEPROM with causing any issues?

 

You should be able to read and write to this device after the configuration is locked depending on how the slots are configured. Here are the steps:

 

  1.     Configure the SlotConfigs, UseFlags and UpdateCount Config (AKA Config Zone)
  2.     Lock the Configuration Zone
  3.     Write your keys to the Slots (aka data zone)
  4.     Write to OTP Zone if required
  5.     Lock OTP and Data Zone

 

The SlotConfig controls how the keys are used and accessed. Depending on how you configure the slots, they can either never be read, allow clear text reads or allow encrypted reads. Writes to the ATSHA204a slots can be done if and only if the slot is configured for the DerivedKey command.

 

As for the Address and Zone encoding, I wrote a tutorial here  that may help you.

 

"When all else fails, read the directions"

Last Edited: Sat. Jun 8, 2019 - 11:20 PM
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