信息论实验报告

信息论实验报告实验四循环汉明码一、实验目的1进一步熟悉汉明码的概念及应用2了解循环码的概念3了解认识循环汉明码，并利用编程实现二、实验内容实现循环汉明码三．实验原理：四、实验代码：#include<iostream>usingnamespacestd;//returnnextstate反馈unsignedcharfn_feedback(unsignedcharn, unsignedcharc, unsignedcharcurr_state){ unsignedchart=c&curr_state; unsignedchars=t&(unsignedchar)128;//getfirstbit for(inti=1;i<n;i++) { s=s^((t<<i)&(unsignedchar)128); } return(unsignedchar)((curr_state<<1)|(s>>(n-1)));//returnnextstate}//产生LFSR序列voidlfsr_output_byte(intn, unsignedcharc, unsignedcharinit_state, unsignedcharoutput_bytes[], intbyte_length){ unsignedcharnext_state=init_state; for(inti=0;i<byte_length;i++) { unsignedchartemp=(unsignedchar)0; for(intj=0;j<8;j++) { temp=temp|((next_state&(unsignedchar)128)>>j); next_state=fn_feedback(n,c,next_state); } output_bytes[i]=temp; }}//outputachartypeofdatainbinaryway//将密钥流输出为二进制voidoutput_binary(unsignedcharc){ for(inti=0;i<8;i++) { if((c<<i)&(unsignedchar)128) cout<<"1"; else cout<<"0"; }}//Geffe生成器voidGeffe(unsignedcharbuf[], unsignedcharbuf1[], unsignedcharbuf2[], unsignedcharb[]){ for(inti=0;i<10;i++) { b[i]=buf[i]*buf1[i]+buf2[i]*buf1[i]+buf2[i]; output_binary((unsignedchar)b[i]); }}//jk触发器voidJK(unsignedcharbuf[],unsignedcharbuf1[],unsignedcharc[]){ for(inti=1;i<11;i++) { c[i]=(buf[i]+buf1[i]+1)*c[i-1]+buf[i]; output_binary((unsignedchar)c[i]); }}//加密解密函数voidcypt(unsignedcharb[]){ unsignedcharcypher[10],cyph[10]; cout<<"inputthecyphertext:"; cin>>cypher; for(intj=0;cypher[j]!='\0';j++) { cyph[j]=cypher[j]^b[j]; cout<<cyph[j]; } cout<<endl; for(intk=0;k<j;k++) { cypher[k]=cyph[k]^b[k]; cout<<cypher[k]; } cout<<endl;}intmain(intargc,char*argv[]){ unsignedcharbuf[10],buf1[10],buf2[10],b[100],c[100]; //函数f初始状态152 lfsr_output_byte(5,(unsignedchar)144,(unsignedchar)152,buf,10); lfsr_output_byte(5,(unsignedchar)44,(unsignedchar)152,buf1,10); lfsr_output_byte(5,(unsignedchar)24,(unsignedchar)152,buf2,10); Geffe(buf,buf1,buf2,b); c[0]=0; JK(buf,buf1,c); cout<<endl; cout<<"Geffeoperate:"<<endl; cypt(b); cout<<endl; cout<<"J-Koperate:"<<endl; cypt(c); return0;}五、实验结果截图：六、实验心得：本次的实验代码相对来说还是比较容易的。实验代码条理清楚，很容易理解。在进行这次的实验时，理解思想和基本的思考过程是很容易的，难点是了解每个函数中间的一些算法和实现过程。因为我们在上密码学课程的时候，老师只是总体的讲解了一些geff