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White-Box Cryptography and an AES Implementation

  • Stanley Chow
  • Philip Eisen
  • Harold Johnson
  • Paul C. Van Oorschot
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2595)

Abstract

Conventional software implementations of cryptographic algorithms are totally insecure where a hostile user may control the execution environment, or where co-located with malicious software. Yet current trends point to increasing usage in environments so threatened. We discuss encrypted-composed-function methods intended to provide a practical degree of protection against white-box (total access) attacks in untrusted execution environments. As an example, we show how aes can be implemented as a series of lookups in key-dependent tables. The intent is to hide the key by a combination of encoding its tables with random bijections representing compositions rather than individual steps, and extending the cryptographic boundary by pushing it out further into the containing application. We partially justify our aes implementation, and motivate its design, by showing how removal of parts of the recommended implementation allows specified attacks, including one utilizing a pattern in the aes SubBytes table.

Keywords

Lookup Table Malicious Software Malicious Host Output Encodings Input Encodings 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Stanley Chow
    • 1
  • Philip Eisen
    • 1
  • Harold Johnson
    • 1
  • Paul C. Van Oorschot
    • 1
  1. 1.Cloakware CorporationOttawaCanada

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