Word Not Reading

#include <ctype.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>

char encrypt(char * ch, char * key);
char decrypt(char * ch, char * key);
char generateKey(char* ch);

int main(int argc, char * argv[])
{
    int choice;
    char ch, j, k;
    bool loop = true;
    FILE *fin, *fout;

    if (argc != 5)
    {
        printf ("Usage: cipher option key infile, outfile\n");
        printf ("Option 1 for encryption and 2 for decryption\n");
        exit(1);
    }

    choice = atoi(argv[1]);
    k = atoi(argv[2]);

    fin = fopen(argv[3], "r");
    fout = fopen(argv[4], "w");

    if (fin ==  NULL || fout == NULL)
    {
        printf("File could not be opened\n");
        exit(1);
    }

    while ( fscanf(fin, "%c", &ch) != EOF )
    {
        if (choice == 1){
            fprintf(fout, "%c", encrypt(ch, k));
        }else if (choice == 2){
            fprintf(fout, "%c", decrypt(ch, k));
        }else {
            printf ("Usage: cipher option key infile, outfile\n");
            printf ("Option 1 for encryption and 2 for decryption\n");
            exit(1);
        }
    }

    fclose(fin);
    fclose(fout);

    return 0;
}

char encrypt(char * word, char * key)
{
    printf("Entered encrypt method.\n");
    printf("%s\n", *word);
    char * alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    int i, j;
    char result = "";

    for (i = 0; i < sizeof(word); i++){
        for (j = 0; j < sizeof(alphabet); j++){
            if (word[i] == alphabet[j]){
                printf("Checking word against alphabet.\n");
                strcat(key[j], result);
                printf("Finished check; appended to result.\n");
                printf("%s\n", result);
            }else if (word[i] == " "){
                strcat(" ", result);
            }
        }
    }