ORYX (encryption algorithm)

For other uses, see Oryx (disambiguation).
For the animal, see Oryx.

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

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:

Lt+32=Lt+26⊕Lt+23⊕Lt+22⊕Lt+16⊕Lt+12⊕Lt+11⊕Lt+10⊕Lt+8⊕Lt+7⊕Lt+5⊕Lt+4⊕Lt+2⊕Lt+1⊕Lt

and

Lt+32=Lt+27⊕Lt+26⊕Lt+25⊕Lt+24⊕Lt+23⊕Lt+22⊕Lt+17⊕Lt+13⊕Lt+11⊕Lt+10⊕Lt+9⊕Lt+8⊕Lt+7⊕Lt+2⊕Lt+1⊕Lt

•The feedback function for LFSRB is:

Lt+32=Lt+31⊕Lt+21⊕Lt+20⊕Lt+16⊕Lt+15⊕Lt+6⊕Lt+3⊕Lt+1⊕Lt

See also

Notes

  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.


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