diff options
Diffstat (limited to 'main.c')
| -rw-r--r-- | main.c | 140 |
1 files changed, 0 insertions, 140 deletions
@@ -1,140 +0,0 @@ -/* - * Copyright (c) 2023 Ian Marco Moffett and the VegaOS team. - * All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions are met: - * - * 1. Redistributions of source code must retain the above copyright notice, - * this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * 3. Neither the name of VegaOS nor the names of its - * contributors may be used to endorse or promote products derived from - * this software without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" - * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE - * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE - * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE - * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR - * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF - * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS - * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN - * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) - * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE - * POSSIBILITY OF SUCH DAMAGE. - */ - -#include <stdio.h> -#include <stdlib.h> -#include <stdint.h> -#include <assert.h> -#include <unistd.h> - -#if __BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__ -#error "Big endian machines not supported yet" -#endif - -#define flip_block(TMP_VAR, TYPE, BUF, POS) \ - TMP_VAR = *(TYPE *)&BUF[POS]; \ - TMP_VAR = ~TMP_VAR; \ - *(TYPE *)&BUF[POS] = TMP_VAR; \ - -static char * -read_file(const char *fname, size_t *size_out) -{ - FILE *fp; - char *buf; - size_t bufsize; - - if (access(fname, F_OK) != 0) { - fprintf(stderr, "%s does not exist!\n"); - return NULL; - } - - fp = fopen(fname, "r"); - - /* Get file size */ - fseek(fp, 0, SEEK_END); - bufsize = ftell(fp); - fseek(fp, 0, SEEK_SET); - - buf = malloc(bufsize); - fread(buf, sizeof(char), bufsize, fp); - fclose(fp); - - *size_out = bufsize; - - return buf; -} - -static void -writeback_file(const char *fname, const char *buf, size_t buf_size) -{ - FILE *fp; - - fp = fopen(fname, "w"); - fwrite(buf, buf_size, sizeof(char), fp); - fclose(fp); -} - -static char * -encrypt(char *buf, size_t buf_size) -{ - size_t current_pos; - size_t step; - uint64_t tmp; - - current_pos = 0; - step = 8; /* Start at 8 bytes (64 bits) */ - - while (current_pos < buf_size) { - /* Ensure we aren't over 8 bytes and a power of two */ - if (step != 1) { - assert((step & 1) == 0 && step <= 8); - } - - switch (step) { - case 8: - flip_block(tmp, uint64_t, buf, current_pos); - break; - case 4: - flip_block(tmp, uint32_t, buf, current_pos); - break; - case 2: - flip_block(tmp, uint16_t, buf, current_pos); - break; - case 1: - flip_block(tmp, uint8_t, buf, current_pos); - break; - } - - current_pos += step; - - /* Ensure we don't cause any overflows */ - while (((current_pos + step) >= buf_size) && step > 1) - /* Essentially divide the step by 2, just faster */ - step >>= 1; - } -} - -int -main(int argc, const char **argv) -{ - size_t buf_size; - char *buf; - - if (argc < 2) { - fprintf(stderr, "Usage: %s <file>\n", argv[0]); - return 1; - } - - buf = read_file(argv[1], &buf_size); - encrypt(buf, buf_size); - writeback_file(argv[1], buf, buf_size); - free(buf); - - return 0; -} |