Fooling primality tests on smartcards

September 14, 2020

We analyse whether the smartcards of the JavaCard platform correctly validate primality of domain parameters.

The work is inspired by Albrecht et al. (Prime and Prejudice), where the authors analysed many open-source libraries and constructed pseudoprimes fooling the primality testing functions. However, in the case of smart-cards, often there is no way to invoke the primality test directly, so we trigger it by replacing (EC)DSA and (EC)DH prime domain parameters by adversarial composites. Such a replacement results in vulnerability to Pohlig-Hellman style attacks, leading to private key recovery. Out of nine smartcards (produced by five major manufacturers) we tested, all butone have no primality test in parameter validation. As the JavaCard platform provides no public primality testing API, the problem cannot be fixed by an extra parameter check, making it difficult to mitigate in already deployed smartcards.


SEDLÁČEK, Vladimír, Ján JANČÁR a Petr ŠVENDA. Fooling primality tests on smartcards. In Liqun Chen, Ninghui Li, Kaitai Liang and Steve Schneider. 25th European Symposium on Research in Computer Security (ESORICS) 2020. Švýcarsko: Springer, 2020. s. 1-21, 21 s. ISBN 978-3-030-59012-3. doi:10.1007/978-3-030-59013-0_11.

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