We first report on the nature of the resulting errors within the hardware due to the physical stress applied to the smartcard. Hereafter, we describe the experiments and results with a very efficient and prominent software RSA-CRT DFA countermeasure. This method could be shown to be insufficient, i.e., detected nearly no error, when we introduced stress at the right position during the computation. Naturally, a detailed error analysis model followed, specifying every failure point during the RSA-CRT operation. This model finally allowed to develop and present here new very practically oriented software countermeasures hedging the observed and characterized fault attacks. Eventually, we present the security analysis of our new developed software RSA-CRT DFA countermeasures. Thanks to their careful specification according to the observed and analyzed errors they resisted all kinds of physical stress attacks and were able to detect any subtle computation error, thus avoiding to break the smartcard by fault attacks.
Nevertheless, we stress, that although our software countermeasures have been fully approved by practical experiments, we are convinced that only sophisticated hardware countermeasures like sensors and filters in combination with software countermeasures will be able to provide a secure and comfortable base to defeat in general any conceivable fault attacks scenario on smartcards properly.Category / Keywords: implementation / Fault attacks, Bellcore attack, Hardware security, Hardware robustness, RSA, Chinese Remainder Theorem, Spike attacks, Transient fault model, Software countermeasures Date: received 4 Jun 2002 Contact author: Jean-Pierre Seifert at infineon com Available formats: Postscript (PS) | Compressed Postscript (PS.GZ) | PDF | BibTeX Citation Version: 20020607:183814 (All versions of this report) Discussion forum: Show discussion | Start new discussion