## A Formal Theory of Key Conjuring

A Formal Theory of Key Conjuring. Véronique Cortier, Stéphanie Delaune, and Graham Steel. In Proceedings of the 20th IEEE Computer Security Foundations Symposium (CSF'07), pp. 79–93, IEEE Computer Society Press, Venice, Italy, July 2007.

### Abstract

We describe a formalism for key conjuring, the process by which an attacker obtains an unknown, encrypted key by repeatedly calling a cryptographic API function with random values in place of keys. This technique has been used to attack the security APIs of several Hardware Security Modules (HSMs), which are widely deployed in the ATM (cash machine) network. We propose a formalism for detecting computationally feasible key conjuring operations, incorporated into a Dolev-Yao style model of the security API. We show that security in the presence of key conjuring operations is decidable for a particular class of APIs, which includes the key management API of IBM's Common Cryptographic Architecture (CCA).

### BibTeX

@inproceedings{CDS-csf07,
author =        {Cortier, V{\'e}ronique and Delaune, St{\'e}phanie and
Steel, Graham},
booktitle =     {{P}roceedings of the 20th {IEEE} {C}omputer
{S}ecurity {F}oundations {S}ymposium ({CSF}'07)},
month =         jul,
pages =         {79-93},
publisher =     {{IEEE} Computer Society Press},
title =         {A Formal Theory of Key Conjuring},
year =          {2007},
abstract =      {We describe a formalism for \emph{key conjuring}, the
process by which an attacker obtains an unknown,
encrypted key by repeatedly calling a cryptographic
API function with random values in place of keys.
This technique has been used to attack the security
APIs of several Hardware Security Modules~(HSMs),
which are widely deployed in the ATM (cash machine)
network. We~propose a formalism for detecting
computationally feasible key conjuring operations,
incorporated into a Dolev-Yao style model of the
security~API. We~show that security in the presence
of key conjuring operations is decidable for a
particular class of~APIs, which includes the key
management~API of IBM's Common Cryptographic
Architecture~(CCA).},
doi =           {10.1109/CSF.2007.5},
}