22F Page 53
This multiplication property is first mentioned in R1 p. 20.
22F THE KEY STREAM
|K||= Χ + Ψ'|
|∴ ΔK||= ΔΧ + Δ Ψ'|
The undifferenced Ψ' stream is flat, therefore the undifferenced K stream is random and unrecognisable statistically [(E3)]
(a) Recognising key on any limitation.
Differencing at distance ωi where ωi is the length of Χi (R3 p. 62)
since we are in effect adding two streams in which ΔKij → ΔΧij with proportinal bulge β
Similarly, differencing at ωi ωj (e.g. 26 x 23 for Χ4 and Χ5)
This result shows that all key maybe recognised by an excess of dots over crosses in Δ598(ΔK45). (R2 p. 90)
and differencing at 31(R2 p. 70) we get
In cases where Δ2Χi and Δ2Χj each → x with high probability Δ2Χij → dot
Now Δ2Ψ'ij → dot