Frequency Postulate's Theoretical Calculation for the Sequences Produced by Modified Geffe Generator
Hussein Ali Mohammed Al Sharifi · Maǧallaẗ ǧāmiʻaẗ Karbalāʼ/Maǧallaẗ ǧāmiʻaẗ karbalāʼ · 2014
The Randomness is one of the basic criterions to measure stream cipher efficiency. The stream cipher generator depends basically on Linear FeedBack Shift Register (LFSR) which is considered as one of the basic units of Stream Cipher Systems (SCS). The basic idea of this paper is attacking and analysis of cryptosystems. So any developing in some kinds of stream cipher generators without taking in considers the basic criteria of efficiency may give no security to the generator, so this paper consists of two parts First, the design part, this paper introduces developing of Geffe generator by increasing the LFSR's from (three) to (five) with new combining nonlinear function which has good statistical properties. The new generator called Modified Geffe generator. Second, the attacking part, the frequency postulate of randomness criteria is calculated theoretically, this mean the generated sequence product by the new generator can estimated and this mean clear weakness in the suggested generator. ةصلاخلا شبتؼت مكشب ذتؼ باغلاا شفشتنا ذنىي ا .باغلاا شفشتنا ىظ ةءافك طاقن تعاعلاا ظاقي ىها ي تئاىشؼنا .باغلاا شفشتنا ىظن تعاعلاا ثاذحىنا ذحأ هىك تفهخنا تزغتنا ور طخنا فحاضنا مجغنا ىهػ عاعا .شفشتنا ىظ مهحتو تجاهي ه تعاعلاا ثحبنا ةشكف ا باغلاا شفشتنا تظا عاىا ضؼب ف شىطت يا اف كنزن .ئضج ي فنات ثحبنا ازه اف كنزن ،ذنىنا تيا ف ةداص يا طؼلا تعاعلاا ةءافكنا ظاقن سابتػلاا شظب زخلاا وذب ثلاجغنا دذػ ةداص للاخ ي فج ذنىي شىطت ىت ثحبنا ازه ف ،ىصتنا ءضج ،لاوا )تغخ( ىنا )تثلاث( ي تفحاضنا .سىطنا فج ذنىي ىػذ ذذجنا ذنىنا .ةذج تئاصحا صاىخ اهن تطخ شغ تبكشي تناد واذختعا غي تجتانا تؼباتتنا خت ك ؼ ازهو ،اشظ تئاىشؼهن ددشتنا تصاخ باغح ،ثحبنا ازه ف ىت ،تجاهنا ءضج ،ااث ناتنابو ذذجنا ذنىنا ي .ذنىنا ىصت ف حضاو فؼض طؼ ازه