Merkle-Hellman背包公钥密码加解密 C语言

#include<stdio.h> void bytetobit(int ch,int bit[8]){ int i; bit[7]=ch&0x01; for(i=1;i<8;i++) { ch=ch>>1; bit[7-i]=ch&0x01; } /*for(i=0;i<8;i++) { printf("%d",bit[i]); }*/ printf("\n"); } void showfile(FILE *fp) { char c; fseek(fp,0,SEEK_SET); printf("文件内容如下：\n"); while(!feof(fp)){ fread(&c,1,1,fp); putchar(c); } } //对文件进行预处理，使其长度为4字节的整倍数 long get_file_size( FILE *fp ) { //char ch[3]={' ',' ',' '}; long flen; if (fp==NULL) return -1; fseek( fp, 0L, SEEK_END ); flen=ftell(fp); /*switch (flen%4) { case 1: fwrite(ch,1,3,fp);break; case 2: fwrite(ch,1,2,fp);break; case 3: fwrite(ch,1,1,fp);break; default: ; } return ftell(fp);*/ } void encryption(){ //给定一个超递增序列B及两个整数W,N，作为密钥 int B[8]={17,53,101,223,503,1009,5857,15641},A[8],W=599,N=53783,S=0,i,j; int M[8]; long flen; char ch; FILE *fp,*fp1; //求其公钥A并输出 printf("公钥为："); for(i=0;i<8;i++) { A[i]=B[i]*W%N; printf("%9d",A[i]); } if(!(fp=fopen("abc.txt","ab+"))) { printf("打开文件失败！"); return; } showfile(fp); //printf("\n%ld",flen); if(!(fp1=fopen("abs.txt","wb"))) { printf("打开abs失败"); return; } flen=get_file_size(fp); fseek(fp,0L,SEEK_SET); for(i=1;i<=flen;i++) { S=0; fread(&ch,sizeof(char),1,fp); bytetobit((int)ch,M); for(j=0;j<8;j++) { S+=M[j]*A[j]; } printf("%9d",S); fwrite(&S,sizeof(int),1,fp1); } fclose(fp);fclose(fp1); } void main() { encryption(); }