Feat: Update readme file to mention local-dev dockerfile

Dockerfile

@@ -1,10 +1,12 @@
-FROM --platform=linux/arm64 alpine:3.20
+FROM alpine:3.20
 
 RUN apk add --no-cache gdb strace
  
 WORKDIR /challenge
 COPY main    ./main
-COPY license ./build/license
 RUN chmod +x ./main
+
+COPY license ./license
+
  
-CMD ["/challenge/main"]
+CMD ["/bin/sh"]

codegen/generate.py

@@ -1,5 +1,6 @@
 import random
 import sys
+import os
 
 def generate_flag(length):
     characters = list("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
@@ -13,7 +14,7 @@ def custom_op_xor(value, amount):
     return (((value << amount) ^ 0xFF) >> amount)
 
 
-manglers = [
+hard_manglers = [
     (lambda value: custom_op_xor(value, 5), lambda value: f"trunc_xor({value}, 5)"),
     (lambda value: custom_op_xor(value, 3), lambda value: f"trunc_xor({value}, 3)"),
     (lambda value: custom_op_xor(value, 2), lambda value: f"trunc_xor({value}, 2)"),
@@ -26,7 +27,17 @@ manglers = [
     # (lambda value: value, lambda value: f"{value}")
 ]
 
-def mangle(value):
+easy_manglers = [
+    (lambda value: value + 1, lambda value: f"{value} + 1"),
+    (lambda value: value - 1, lambda value: f"{value} - 1"),
+    (lambda value: value * 2, lambda value: f"{value} * 2"),
+    (lambda value: value ^ 0xAB, lambda value: f"({value} ^ 0xAB)"),
+    (lambda value: value, lambda value: f"{value}")
+]
+
+
+
+def mangle(value, manglers):
     result = b""
     c_manglers = []
 
@@ -42,11 +53,18 @@ def mangle(value):
 
     return (result, c_manglers)
 
-def get_check_code(flag_part, user_part, c_mangler):
-    variations = [
-        f"custom_jmp_neq({flag_part} ^ 0x7C, {c_mangler(user_part)},        label_false);",
-        f"custom_jmp_neq({flag_part},        {c_mangler(user_part)} ^ 0x7C, label_false);"
-    ]
+def get_check_code(flag_part, user_part, c_mangler, difficulty):
+
+    if difficulty == "HARD":
+        variations = [
+            f"custom_jmp_neq({flag_part} ^ 0x7C, {c_mangler(user_part)},        label_false);",
+            f"custom_jmp_neq({flag_part},        {c_mangler(user_part)} ^ 0x7C, label_false);"
+        ]
+    else: 
+        variations = [
+            f"if({flag_part} != {c_mangler(user_part)}) {{ return false; }}"
+        ]
+
     return random.choice(variations)
 
 def main():
@@ -64,6 +82,8 @@ def main():
         if flag_seed.lower() != "false":
             random.seed("totallysecurepadding" + flag_seed + "sonoonecanguesstheflag!")
 
+    difficulty = os.getenv("DIFFICULTY", "EASY")
+
     # Generate a secret
     secret = generate_flag(flag_len)
     secret = flag_format.replace("FLAG_GOES_HERE", secret)
@@ -71,7 +91,7 @@ def main():
     eprint(f"Generated Flag: {secret}")
 
     # Change the bytes of the secret
-    mangled_secret, c_manglers = mangle(secret)
+    mangled_secret, c_manglers = mangle(secret, easy_manglers if difficulty == "EASY" else hard_manglers)
 
     # Shuffle the secret, but keep track of the order
     # We need this so we know the real location of the characters to compare
@@ -89,7 +109,7 @@ def main():
 
     checks = []
     for i, c_mangler in enumerate(c_manglers):
-        checks.append(get_check_code(f"MANGLED[{i}]", f"userflag[{secret_shuffleorder[i]}]", c_mangler))
+        checks.append(get_check_code(f"MANGLED[{i}]", f"userflag[{secret_shuffleorder[i]}]", c_mangler, difficulty))
     
     random.shuffle(checks)
     check = "\n".join(checks)
@@ -108,7 +128,7 @@ def main():
 static volatile uint8_t MANGLED[] = "{mangled_secret}";
 
 bool check(char* userflag, uint8_t len) {{
-    custom_jmp_neq(len ^ 0x7C, {len(secret)}, label_false);
+    {f"custom_jmp_neq(len ^ 0x7C, {len(secret)}, label_false);" if difficulty == "HARD" else f"if (len != {len(secret)}) {{ return false; }}"}
 
     {check}
 

src/encryptor.c

@@ -109,6 +109,8 @@ int main(int argc, char** argv) {
     fprintf(f_readme, "This doesn't just run on any hardware, I don't know how they did it\n");
     fprintf(f_readme, "but it only works on my %s processor\n", hwinfo.model_name);
     fprintf(f_readme, "running linux (version %s) with %s kb of RAM\n", hwinfo.os_version, hwinfo.mem_total);
+    fprintf(f_readme, "I also included a dockerfile so you can run all that shi easier.\n");
+    fprintf(f_readme, "Just unzip that thang and run docker build . -t local-dev and then docker run -it local-dev in the folder you unzipped to.\n");
     fprintf(f_readme, "You'll find a way, slime. I'm sorry that I can't give you any more details\n");
     fprintf(f_readme, "this is the last message I could get out before they... you know... ⛓️‍👮‍♂️\n");
     fprintf(f_readme, "\n");

src/spoof/spoofer.c

@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <dlfcn.h>
+#include <unistd.h>
 
 static FILE *(*real_fopen)(const char *path, const char *mode) = NULL;
 
@@ -38,3 +39,19 @@ FILE *fopen(const char *path, const char *mode) {
 
     return real_fopen(path, mode);
 }
+
+FILE *tmpfile(void) {
+    char path[] = "./tmpfile_XXXXXX";
+    int fd = mkstemp(path);
+    if (fd == -1) {
+        fprintf(stderr, "proc_redirect: mkstemp failed\n");
+        abort();
+    }
+    fprintf(stderr, "proc_redirect: tmpfile created at %s\n", path);
+    FILE *f = fdopen(fd, "w+");
+    if (!f) {
+        close(fd);
+        abort();
+    }
+    return f;
+}