Ask a new question Source codeĭCode retains ownership of the "Linear Feedback Shift Register" source code. A5/1.Choose which bits will be used by the XOR function and launch the iteration(s). You may find test vectors for some algorithms which use one or several LFSR in an asynchronous fashion, e.g.
Consequently, you will not find test vectors for "a lone asynchronous LFSR" because there is no such thing as a LFSR being asynchronous by itself: asynchronicity stems from an extra piece which controls whether the LFSR shall be clocked or not. From the point of view of the LFSR, nothing is changed: when a "clock" occurs, one bit is produced and the internal state is updated. Being asynchronous is not a property of the LFSR itself, but of how it is invoked. An "asynchronous" LFSR is a LFSR which you do not always clock, based on some externally specified arbitrary rule.
The pedagogical A5/1 implementation (which is the only publicly known "reference" on A5/1) contains a single test vector, which the code actually tests when executed (see the test() function).Ī LFSR is a structure which produces a sequence of bits from on internal state at each "clock", a single bit is output, and the internal state is correspondingly updated.
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