Paper 2007/134

Estimation of keys stored in CMOS cryptographic device after baking by using the charge shift

Osman Kocar


The threshold voltage VT of EEPROM cells is a very important technological parameter for storing data and keys in a cryptographic device like smartcards. Furthermore, main objective of this paper is to check whether it is possible to get the key stored in the EEPROM cell through measuring the current consumption of the cryptographic device during read key command for encryption before and after baking at a certain temperature. This stress (baking) of the charge in the floating gate of the cells shifts the threshold voltage. Especially this effect will be considered whether the unknown key in the EEPROM cells can be estimated by using the charge shift in the floating gate. The test labs might need to check during an evaluation procedure of the smartcards if parts or whole key can be estimated successfully by stressing the threshold parameter VT. The result of this evaluation is (will be) an input for countermeasures against possible attacks. It is also an additional input for further design structures in order to avoid information gain after baking the EEPROM cells at a certain temperature.

Available format(s)
Publication info
Published elsewhere. Unknown where it was published
Differential Charge AnalysisSide Channel AnalysisSmart Cards
Contact author(s)
osman kocar @ bsi bund de
2007-04-18: received
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Creative Commons Attribution


      author = {Osman Kocar},
      title = {Estimation of keys stored in {CMOS} cryptographic device after baking by using the charge shift},
      howpublished = {Cryptology ePrint Archive, Paper 2007/134},
      year = {2007},
      note = {\url{}},
      url = {}
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