Add final challenge filesHEADmaster

7 files changed, 227 insertions, 0 deletions

diff --git a/meta/.gitignore b/meta/.gitignore
new file mode 100644
index 0000000..f3880fa
--- /dev/null
+++ b/meta/.gitignore
@@ -0,0 +1 @@
+recover
diff --git a/meta/Makefile b/meta/Makefile
new file mode 100644
index 0000000..c3b984e
--- /dev/null
+++ b/meta/Makefile
@@ -0,0 +1,11 @@
+CFLAGS = -g
+LDLIBS = -lraylib
+
+all: recover
+
+clean:
+	rm -f recover
+
+recover: recover.c
+
+.PHONY: all clean
diff --git a/meta/encrypt.py b/meta/encrypt.py
new file mode 100644
index 0000000..5451f4a
--- /dev/null
+++ b/meta/encrypt.py
@@ -0,0 +1,10 @@
+#!/usr/bin/env python3
+
+from Crypto.Cipher import AES
+import os, sys
+
+img_in = open(sys.argv[1], "rb").read()
+img_in += b'\00' * (16 - (len(img_in) % 16))
+cipher = AES.new(os.urandom(16), AES.MODE_ECB)
+img_out = cipher.encrypt(img_in)
+open(sys.argv[1] + ".enc", "wb+").write(img_out)
diff --git a/meta/flag.bmp b/meta/flag.bmp
new file mode 100644
index 0000000..091c585
--- /dev/null
+++ b/meta/flag.bmp
diff --git a/meta/flag.bmp.enc b/meta/flag.bmp.enc
new file mode 100644
index 0000000..4f7ecfe
--- /dev/null
+++ b/meta/flag.bmp.enc
diff --git a/meta/recover.c b/meta/recover.c
new file mode 100644
index 0000000..54574b6
--- /dev/null
+++ b/meta/recover.c
@@ -0,0 +1,150 @@
+#include "raylib.h"
+
+#include <err.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+#define BLOCKSIZE 16
+#define BESTN 4
+
+struct block {
+	uint8_t data[BLOCKSIZE];
+	uint32_t cnt;
+};
+
+uint8_t *
+read_file(const char *filename, size_t *size)
+{
+	uint8_t *buf;
+	FILE *f;
+
+	f = fopen(filename, "r");
+	if (!f) err(1, "fopen");
+
+	fseek(f, 0, SEEK_END);
+	*size = ftell(f);
+	fseek(f, 0, SEEK_SET);
+
+	buf = malloc(*size);
+	if (!buf) err(1, "malloc");
+
+	if (!fread(buf, *size, 1, f))
+		err(1, "fread");
+
+	fclose(f);
+
+	return buf;
+}
+
+void
+update(struct block *blocks, struct block *bestblocks,
+	size_t *blockslen, uint8_t *img, size_t imglen)
+{
+	struct block cmp, tmp;
+	size_t tmpcnt;
+	size_t i, k;
+
+	memset(bestblocks, 0, BESTN * sizeof(struct block));
+	*blockslen = 0;
+	for (i = 0; i < imglen - BLOCKSIZE + 1; i += BLOCKSIZE) {
+		for (k = 0; k < *blockslen; k++) {
+			if (!memcmp(blocks[k].data, &img[i], BLOCKSIZE)) {
+				blocks[k].cnt += 1;
+				break;
+			}
+		}
+		if (k == *blockslen) {
+			memcpy(blocks[k].data, &img[i], BLOCKSIZE);
+			blocks[k].cnt = 1;
+			*blockslen += 1;
+		}
+
+		memcpy(&cmp, &blocks[k], sizeof(struct block));
+		for (k = 0; k < BESTN; k++) {
+			if (cmp.cnt > bestblocks[k].cnt || !bestblocks[k].cnt) {
+				memcpy(&tmp, &bestblocks[k], sizeof(struct block));
+				memcpy(&bestblocks[k], &cmp, sizeof(struct block));
+				memcpy(&cmp, &tmp, sizeof(struct block));
+			}
+		}
+	}
+}
+
+
+int
+main(int argc, const char **argv)
+{
+	const int wwidth = 1920;
+	const int wheight = 1080;
+	struct block bestblocks[BESTN];
+	struct block *blocks;
+	char textbuf[256];
+	size_t blockslen;
+	size_t imgoff, imglen;
+	size_t width, height;
+	size_t x, y, pos, i;
+	uint8_t *img;
+
+	if (argc < 2) return 1;
+
+	img = read_file(argv[1], &imglen);
+
+	blocks = malloc(imglen / BLOCKSIZE * sizeof(struct block));
+	if (!blocks) err(1, "malloc");
+
+	InitWindow(wwidth, wheight, "bmpass");
+
+	update(blocks, bestblocks, &blockslen, img, imglen);
+
+	width = wwidth;
+	imgoff = 0;
+	while (!WindowShouldClose()) {
+		if (IsKeyDown(KEY_LEFT) && width > 0)
+			width -= 1;
+		else if (IsKeyDown(KEY_RIGHT))
+			width += 1;
+		else if (IsKeyDown(KEY_DOWN) && imgoff > 0)
+			imgoff -= BLOCKSIZE;
+		else if (IsKeyDown(KEY_UP))
+			imgoff += BLOCKSIZE;
+		else if (IsKeyDown(KEY_ESCAPE))
+			break;
+
+		BeginDrawing();
+
+		ClearBackground(GRAY);
+
+		height = (imglen - imgoff) / width;
+		for (y = 0; y < height; y++) {
+			if (y >= wheight) continue;
+			for (x = 0; x < width; x++) {
+				if (x >= wwidth) continue;
+				pos = (imgoff + y * width + x)
+					/ BLOCKSIZE * BLOCKSIZE;
+				if (pos + BLOCKSIZE >= imglen) continue;
+				for (i = 0; i < BESTN; i++) {
+					if (!memcmp(bestblocks[i].data,
+							img + pos, BLOCKSIZE))
+						break;
+				}
+				if (i != BESTN)
+					DrawPixel(x, wheight - 1 - y, BLACK);
+				else
+					DrawPixel(x, wheight - 1 - y, WHITE);
+			}
+		}
+
+		snprintf(textbuf, sizeof(textbuf), "imgoff %lu", imgoff);
+		DrawText(textbuf, 10, wheight - 40, 20, BLACK);
+
+		snprintf(textbuf, sizeof(textbuf), "width %lu", width);
+		DrawText(textbuf, 10, wheight - 20, 20, BLACK);
+
+		EndDrawing();
+	}
+
+	CloseWindow();
+}
diff --git a/meta/recover.py b/meta/recover.py
new file mode 100644
index 0000000..72b3a6c
--- /dev/null
+++ b/meta/recover.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+
+from pyray import *
+import struct
+import sys
+
+img_enc = open(sys.argv[1], "rb").read()
+
+
+blocksize = 16
+
+pix = img_enc[0x480:] # offset needs to be blocksize aligned
+img_off = 0x0a
+
+print(len(pix) - img_off, 1920 * 1080)
+
+blocks = {}
+for i in range(0, len(pix)-blocksize+1, blocksize):
+    block = pix[i:i+blocksize]
+    if block not in blocks:
+        blocks[block] = []
+    blocks[block].append(i)
+blocks_items = [(k,len(v)) for k,v in blocks.items()]
+blocks_sorted = sorted(blocks_items, key=lambda x: x[1], reverse=True)[8:]
+blocks_top = {k:v for k,v in blocks_sorted}
+
+imgbuf = []
+for i in range(0, len(pix)-blocksize+1, blocksize):
+    block = pix[i:i+blocksize]
+    if block not in blocks_top:
+        imgbuf += [Color(255, 255, 255, 255)] * blocksize
+    else:
+        imgbuf += [Color(0, 0, 0, 255)] * blocksize
+
+width = 1920
+init_window(1920, 1080, "bmpass")
+while not window_should_close():
+    while key := get_key_pressed():
+        if key == KEY_LEFT:
+            width -= 1
+        elif key == KEY_RIGHT:
+            width += 1
+        elif key == KEY_UP and img_off > 0:
+            img_off -= 1
+        elif key == KEY_DOWN:
+            img_off += 1
+    begin_drawing()
+    clear_background(GRAY)
+    height = len(imgbuf) // width
+    for y in range(height):
+        for x in range(width):
+            draw_pixel(x, height - 1 - y, imgbuf[img_off + y * width + x])
+    end_drawing()
+close_window()
+