Usenet 1994 January/usenetsourcesnewsgroupsinfomagicjanuary1994.iso/sources/unix/volume17/hill/hill0.c

C/C++ Source or Header | 1989-02-08 | 3.8 KB | 212 lines

^X# include <stdio.h>
^X# include "table.i"
^X# ifdef DOS
^X# include <fcntl.h>
^X# include <io.h>
^X# endif
^X
^X# ifdef DOS
^X# define TTY "con"
^X# else
^X# define TTY "/dev/tty"
^X# endif
^X
^X# define Over(x) for (x = 0; x < order; x++)
^X# define Times(a,b) ((long)(a) * (long)(b) % 257)
^X
^Xint mode;
^X
^Xchar key[256];
^Xint matkey[16][16];
^Xint invec[16];
^Xint outvec[16];
^Xint order;
^X
^X
^Xsetup(argc, argv)
^Xint argc; char **argv;
^X    {
^X    FILE *tty;
^X
^X    if (strcmp(argv[1], "-e") == 0)
^X        mode = 'e';
^X    else if (strcmp(argv[1], "-d") == 0)
^X        mode = 'd';
^X    else {
^X        fprintf(stderr, "usage: hill -e [key]\n   or: hill -d [key]\n");
^X        exit(1);
^X        }
^X    if (argc > 2)
^X        strcpy(key, argv[2]);
^X    else {
^X        tty = fopen(TTY, "r+");
^X        setbuf(tty, NULL);
^X        fprintf(tty, "Key? ");
^X        fgets(key, sizeof(key), tty);
^X        key[strlen(key) - 1] = 0;
^X        fclose(tty);
^X        }
^X    }
^X
^Xmakemat()
^X    {
^X    int i, j, k;
^X    int n = 0;
^X    FILE *tty;
^X
^X    setorder();
^X    Over(i) Over(j)
^X        matkey[i][j] = key[n++];
^X    for (i = 0; i < strlen(key); i++)
^X        key[i] = 0;
^X    square();
^X    while ((k = invert()) != EOF)
^X        matkey[k][k] = (matkey[k][k] + 1) % 257;
^X    }
^X
^Xsetorder()
^X    {
^X    int n = strlen(key);
^X
^X    for (order = 0; order < 17; order++)
^X        if (order*order > n) break;
^X    order--;
^X    if (order < 3) {
^X        fprintf(stderr, "key size < 9\n");
^X        exit(1);
^X        }
^X    }
^X
^Xsquare()
^X    {
^X    int result[16][16];
^X    int i, j, k;
^X
^X    Over(i) Over(j)
^X        result[i][j] = 0;
^X    Over(i) Over(j) Over(k)
^X        result[i][j] += Times(matkey[i][k], matkey[k][j]);
^X    Over(i) Over(j)
^X        matkey[i][j] = result[i][j] % 257;
^X    }
^X
^Xint invert()
^X    {
^X    int matrix[16][16];
^X    int inverse[16][16];
^X    int i, j, k;
^X    int t;
^X    int pivot;
^X
^X    Over(i) Over(j) {
^X        matrix[i][j] = matkey[i][j];
^X        inverse[i][j] = 0;
^X        }
^X    Over(k)
^X        inverse[k][k] = 1;
^X
^X    Over(k) {
^X        if (matrix[k][k] == 0) {
^X            for (i = k + 1; i < order; i++)
^X                if (matrix[i][k]) {
^X                    Over(j) {
^X                        t = matrix[i][j];
^X                        matrix[i][j] = matrix[k][j];
^X                        matrix[k][j] = t;
^X                        t = inverse[i][j];
^X                        inverse[i][j] = inverse[k][j];
^X                        inverse[k][j] = t;
^X                        }
^X                    break;
^X                    }
^X            if (i == order) return(k);
^X            }
^X
^X        pivot = inverses[matrix[k][k]];
^X        Over(j) {
^X            matrix[k][j] = Times(matrix[k][j], pivot);
^X            inverse[k][j] = Times(inverse[k][j], pivot);
^X            }
^X        Over(i) if (i != k) {
^X            pivot = matrix[i][k];
^X            Over(j) {
^X                matrix[i][j] -= Times(pivot, matrix[k][j]);
^X                if (matrix[i][j] < 0) matrix[i][j] += 257;
^X                inverse[i][j] -= Times(pivot, inverse[k][j]);
^X                if (inverse[i][j] < 0) inverse[i][j] += 257;
^X                }
^X            }
^X        }
^X
^X    if (mode == 'd') Over(i) Over(j)
^X        matkey[i][j] = inverse[i][j];
^X    return(EOF);
^X    }
^X
^X
^Xint getvec()
^X    {
^X    int i;
^X    int padf = 0;
^X
^X    Over(i)
^X        if ((invec[i] = getchar()) == EOF) {
^X            if (i == 0) return(0);
^X            else if (padf) invec[i] = rand() % 257;
^X            else { invec[i] = 256; padf++; }
^X            }
^X        else if (invec[i] == 255 && mode == 'd')
^X            invec[i] += getchar();
^X    return(i);
^X    }
^X
^Xputvec()
^X    {
^X    int j;
^X
^X    Over(j)
^X        switch(outvec[j]) {
^X        case 256:
^X            if (mode == 'd') return;
^X            else putchar(255), putchar(1);
^X            break;
^X        case 255:
^X            putchar(255);
^X            if (mode == 'e') putchar(0);
^X            break;
^X        default:
^X            putchar(outvec[j]);
^X            }
^X    }
^X
^Xmatmul()
^X    {
^X    int i, j, k;
^X
^X    Over(i) {
^X        outvec[i] = 0;
^X        Over(j)
^X            outvec[i] += Times(invec[j], matkey[i][j]);
^X        outvec[i] %= 257;
^X        }
^X    }
^X
^Xmain(argc, argv)
^Xint argc; char **argv;
^X    {
^X    long tloc;
^X
^X# ifdef DOS
^X;setmode(fileno(stdin), O_BINARY);
^X    setmode(fileno(stdout), O_BINARY);
^X# endif
^X    time(&tloc);
^X    srand((int) tloc);
^X    setup(argc, argv);
^X    makemat();
^X    while(getvec()) {
^X;    matmul();
^X;    putvec();
^X;;}
^X    }