FILE *openFile, *resultFile;
    char buffer[8], key[8] = "01234567";
    if ((openFile = fopen("c:/dev/encoding/test.xlsx", "rb")) == NULL) {
        printf("Cannot open file.n");
        exit(1);
    }
    if ((resultFile = fopen("c:/dev/encoding/test.enc", "wb")) == NULL) {
        printf("Cannot open file.n");
        exit(1);
    }
    fread(buffer, sizeof(char), 8, openFile);
    do {
        encrypt(buffer, key);
        if ((fwrite(buffer, sizeof(char), 8, resultFile)) != 8) {
            printf("Fatal Error writing output file!!!n");
            exit(-1);
        }
        fread(buffer, sizeof(char), 8, openFile);
    } while (!feof(openFile));
    fclose(openFile);
    fclose(resultFile);