ORYX (encryption algorithm)

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ORYX is an encryption algorithm used in cellular communications in order to protect data traffic. It is a stream cipher designed to have a very strong 96-bit key strength with a way to reduce the strength to 32-bits for export. However, due to mistakes the actual strength is a trivial 16-bits and any signal can be cracked after the first 25-27 bytes.[1]

Algorithm Description[edit]

ORYX is a simple stream cipher based on binary linear feedback shift registers (LFSRs) to protect cellular data transmissions(for wireless data services). The cipher ORYX has four components: three 32-bit LFSRs which labeled as LFSRA, LFSRB and LFSRK, and an S-box containing a known permutation P of the integer values 0 to 255.

•The feedback function for LFSRK is defined as:

Lt+32= Lt+28⊕Lt+19⊕Lt+18⊕Lt+16⊕Lt+14⊕Lt+11⊕Lt+10⊕Lt+9⊕Lt+6⊕Lt+5⊕Lt+1⊕Lt

•The feedback functions for LFSRA are defined as:




•The feedback function for LFSRB is:


See also[edit]

  • A5/1, used in the GSM cellular telephone standard.
  • CMEA, Cellular Message Encryption Algorithm.


  1. ^ [D. Wagner, L. Simpson, E. Dawson, J. Kelsey, W. Millan, and B. Schneier http://www.schneier.com/paper-oryx.pdf "Cryptanalysis of ORYX"], Fifth Annual Workshop on Selected Areas in Cryptography, Springer Verlag, August 1998, to appear.

External links[edit]