Init.HEADmaster

11 files changed, 1300 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..4d24a79
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+openssl-1.1.0f
\ No newline at end of file
diff --git a/LostKey b/LostKey
new file mode 100755
index 0000000..cf1015b
--- /dev/null
+++ b/LostKey
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..56c3c34
--- /dev/null
+++ b/README.md
@@ -0,0 +1,22 @@
+LostKey
+===
+
+# Author
+n0p
+
+# Description
+You know the area around your house at the edge of the world quite well. However,
+the world is big and its edge is long. To have a look at the other parts of the
+world's edge, you took one month off and planned a road trip. But you just can't
+seem to find your car key...
+Luckily you've left yourself some hints where you might find it, as this is not
+the first time you forgot where you've put it!
+
+# Solution
+See notes.txt and rop_in_c.c
+
+# Point Value
+350
+
+# Flag
+flag{Th3_key_1s_in_th3_secret_comp4rtment_of_your_t00l_sh3d...}
diff --git a/build.sh b/build.sh
new file mode 100755
index 0000000..39a1e0c
--- /dev/null
+++ b/build.sh
@@ -0,0 +1,9 @@
+rm LostKey
+cd openssl-1.1.0f
+CC=clang ./Configure no-shared -m32 linux-generic32 -O0
+make -j 16 all
+cd ..
+clang -s -static -m32 lost_key.c rop.c -L openssl-1.1.0f -l:libcrypto.a -oLostKey
+cd openssl-1.1.0f
+make clean
+cd ..
diff --git a/encrypt_decoy.c b/encrypt_decoy.c
new file mode 100644
index 0000000..3cde750
--- /dev/null
+++ b/encrypt_decoy.c
@@ -0,0 +1,80 @@
+/*
+ * gcc encrypt_decoy.c -lcrypto
+ */
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "openssl/aes.h"
+
+int main() {
+  AES_KEY enc_key;
+
+  unsigned char plain[80] =
+      "Oh my, there's nothing here... Move along, but don't fall off the "
+      "edge!\0",
+                keys[4][16], cipher[4][80];
+
+  // Getting 4 random 128 bit keys.
+  int fd = open("/dev/urandom", O_RDONLY);
+  if (fd == -1) {
+    exit(-1);
+  }
+
+  for (int i = 0; i < 4; i++) {
+    if (read(fd, keys[i], 16) != 16) {
+      exit(-1);
+    }
+  }
+
+  close(fd);
+
+  // Encrypting the plain text with the 4 keys to 4 cipher texts.
+  for (int i = 0; i < 4; i++) {
+    AES_set_encrypt_key(keys[i], 128, &enc_key);
+
+    for (int j = 0; j < 5; j++) {
+      AES_encrypt(plain + 16 * j, cipher[i] + 16 * j, &enc_key);
+    }
+  }
+
+  // PP the key for copy & paste to the challenge source.
+  for (int i = 0; i < 4; i++) {
+    if (i == 0) {
+      printf("static unsigned char decoy_keys[4][16] = {{");
+    } else {
+      printf("                                          {");
+    }
+
+    for (int j = 0; j < 16; j++) {
+      if (j == 15) {
+        printf("'\\x%02X'", keys[i][j]);
+      } else {
+        printf("'\\x%02X', ", keys[i][j]);
+      }
+    }
+
+    if (i == 3) {
+      printf("}};\n");
+    } else {
+      printf("},\n");
+    }
+  }
+
+  // PP the cipher texts.
+  for (int i = 0; i < 4; i++) {
+    printf("static const unsigned char cipher[80] = {");
+
+    for (int j = 0; j < 80; j++) {
+      if (j == 79) {
+        printf("'\\x%02X'};\n", cipher[i][j]);
+      } else {
+        printf("'\\x%02X', ", cipher[i][j]);
+      }
+    }
+  }
+
+  return 0;
+}
\ No newline at end of file
diff --git a/lost_key.c b/lost_key.c
new file mode 100644
index 0000000..9c8a06a
--- /dev/null
+++ b/lost_key.c
@@ -0,0 +1,534 @@
+#define _GNU_SOURCE
+#include <sched.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "openssl/aes.h"
+#include "openssl/md5.h"
+
+#include "rop.h"
+
+static void create() __attribute__((constructor));
+static void destroy() __attribute__((destructor));
+
+int flag_0(void *);
+int flag_1(void *);
+int flag_2(void *);
+int flag_3(void *);
+
+struct clone_args {
+  unsigned char *decoy_key;
+  char *argv;
+};
+
+static char flag[100] = {0};
+// Final key: {0xC2E1FAFF, 0xFFFAE1C2, 0xFFFAE1C2, 0xC2E1FAFF}
+uint32_t tea_key[4] = {0};
+
+static unsigned char decoy_keys[4][16] = {
+    {'\xBF', '\xE3', '\x80', '\x6E', '\x8C', '\xB7', '\x0A', '\x4E', '\x6E',
+     '\x96', '\x00', '\x63', '\x88', '\x00', '\x09', '\x9E'},
+    {'\xC7', '\x7F', '\x3A', '\x98', '\xB1', '\xD3', '\x12', '\xC0', '\x14',
+     '\x5E', '\x29', '\xEE', '\x42', '\x76', '\xE8', '\x27'},
+    {'\xA7', '\x2B', '\x91', '\x7D', '\x05', '\xB8', '\xBC', '\x4B', '\x6A',
+     '\xA9', '\x02', '\x4F', '\x13', '\xF2', '\xBB', '\x9D'},
+    {'\xAD', '\x6E', '\xFB', '\xE2', '\x4C', '\x2E', '\x26', '\xD9', '\x7A',
+     '\x6B', '\x68', '\xB2', '\x37', '\xC7', '\xA7', '\x35'}};
+
+static void *stack = NULL;
+static size_t stack_size = 1024 * 1024;
+
+static uintptr_t flag_funcs[] = {(uintptr_t)flag_0, (uintptr_t)flag_1,
+                                 (uintptr_t)flag_2, (uintptr_t)flag_3};
+
+int main(int argc, char *argv[]) {
+  if (argc != 5 || stack == NULL) {
+    return -1;
+  }
+
+  printf("Speak, flag, and get your key's location.\n");
+
+  for (int i = 0; i < 4; i++) {
+    struct clone_args *args = malloc(sizeof(struct clone_args));
+    args->decoy_key = decoy_keys[i];
+    args->argv = argv[i + 1];
+
+    pid_t pid = clone((int (*)(void *))flag_funcs[i],
+                      stack + stack_size - (i + 1) * 0x1000, CLONE_VM | SIGCHLD,
+                      (void *)args);
+
+    if (waitpid(pid, NULL, 0) == -1) {
+      return -1;
+    }
+
+    free(args);
+  }
+
+  printf("Did you speak flag?\n%s\n", flag);
+
+  return 0;
+}
+
+int flag_0(void *key) {
+  if (ptrace(PTRACE_TRACEME, 0, 0, 0) == 0) {
+    tea_key[0] = 0x466C7578;
+    tea_key[1] = 0x78756C46;
+    tea_key[2] = 0x78756C46;
+    tea_key[3] = 0x466C7578;
+  }
+
+  *(uintptr_t *)(&key - 1) = (uintptr_t)rop_get_arg;
+
+  if (ptrace(PTRACE_TRACEME, 0, 0, 0) == -1) {
+    tea_key[0] ^= 0x6861636B;
+    tea_key[1] ^= 0x6B636168;
+    tea_key[2] ^= 0x6B636168;
+    tea_key[3] ^= 0x6861636B;
+  }
+
+  static const unsigned char cipher[80] = {
+      '\x35', '\x6F', '\x21', '\xDE', '\xF7', '\xBD', '\x78', '\xFE', '\x6D',
+      '\xB1', '\x3C', '\xC6', '\xBC', '\x49', '\x9C', '\xA9', '\x14', '\x44',
+      '\x5C', '\xAC', '\x2B', '\xFD', '\xB9', '\x56', '\x7E', '\x62', '\xB1',
+      '\x59', '\x6B', '\x7B', '\xFE', '\x75', '\xA1', '\x29', '\x31', '\xBC',
+      '\x8F', '\x46', '\x51', '\x73', '\x52', '\x3A', '\xA0', '\xAC', '\x94',
+      '\x7C', '\x9E', '\xC2', '\x03', '\xE0', '\xE4', '\xA4', '\x23', '\x11',
+      '\x39', '\x10', '\x70', '\xC6', '\x96', '\x22', '\x99', '\xC5', '\x7A',
+      '\x53', '\xEF', '\xC1', '\xD9', '\x0E', '\x01', '\x8C', '\x1F', '\x18',
+      '\xB1', '\x70', '\x95', '\x80', '\xD5', '\x9E', '\xC4', '\xCC'};
+
+  if (key == NULL || ((struct clone_args *)key)->decoy_key == NULL ||
+      ((struct clone_args *)key)->argv == NULL) {
+    return -1;
+  }
+
+  AES_KEY dec_key;
+  unsigned char plain[17] = {0};
+
+  if (AES_set_decrypt_key(((struct clone_args *)key)->decoy_key, 128,
+                          &dec_key) != 0) {
+    return -1;
+  }
+
+  for (int i = 0; i < 5; i++) {
+    AES_decrypt(cipher + 16 * i, plain, &dec_key);
+    printf("%s", plain);
+  }
+
+  printf("\n");
+
+  return 0;
+}
+
+int flag_1(void *key) {
+  if (ptrace(PTRACE_TRACEME, 0, 0, 0) == 0) {
+    tea_key[0] ^= 0xFFFFFFFF;
+    tea_key[1] ^= 0xFFFFFFFF;
+    tea_key[2] ^= 0xFFFFFFFF;
+    tea_key[3] ^= 0xFFFFFFFF;
+  }
+
+  *(uintptr_t *)(&key - 1) = (uintptr_t)rop_get_arg;
+
+  if (ptrace(PTRACE_TRACEME, 0, 0, 0) == -1) {
+    tea_key[0] ^= 0x01010101;
+    tea_key[1] ^= 0x01010101;
+    tea_key[2] ^= 0x01010101;
+    tea_key[3] ^= 0x01010101;
+  }
+
+  static const unsigned char cipher[80] = {
+      '\x6B', '\xB1', '\x28', '\x40', '\x27', '\xD6', '\xF1', '\x4D', '\x61',
+      '\x5E', '\x09', '\x72', '\xED', '\xDF', '\x01', '\xBF', '\x2E', '\x88',
+      '\xEF', '\x43', '\xF8', '\xDD', '\x79', '\xAF', '\xBE', '\x1A', '\x00',
+      '\x1B', '\xC6', '\x41', '\x14', '\x2A', '\xBC', '\x00', '\xBE', '\x7C',
+      '\xA7', '\xAB', '\xF1', '\x27', '\xDA', '\xE6', '\xAC', '\xAC', '\xAE',
+      '\xC8', '\x72', '\x04', '\x79', '\x39', '\x07', '\x61', '\x53', '\x36',
+      '\x03', '\x33', '\xEA', '\x41', '\xD1', '\x77', '\xCD', '\x59', '\x7C',
+      '\xC8', '\xC6', '\xB9', '\xD9', '\x05', '\xCE', '\x89', '\x56', '\x59',
+      '\x8E', '\x98', '\x3B', '\x19', '\x22', '\x10', '\x10', '\x59'};
+
+  if (key == NULL || ((struct clone_args *)key)->decoy_key == NULL ||
+      ((struct clone_args *)key)->argv == NULL) {
+    return -1;
+  }
+
+  AES_KEY dec_key;
+  unsigned char plain[17] = {0};
+
+  if (AES_set_decrypt_key(((struct clone_args *)key)->decoy_key, 128,
+                          &dec_key) != 0) {
+    return -1;
+  }
+
+  for (int i = 0; i < 5; i++) {
+    AES_decrypt(cipher + 16 * i, plain, &dec_key);
+    printf("%s", plain);
+  }
+
+  printf("\n");
+
+  return 0;
+}
+
+int flag_2(void *key) {
+  if (ptrace(PTRACE_TRACEME, 0, 0, 0) == 0) {
+    tea_key[0] ^= 0x10101010;
+    tea_key[1] ^= 0x10101010;
+    tea_key[2] ^= 0x10101010;
+    tea_key[3] ^= 0x10101010;
+  }
+
+  *(uintptr_t *)(&key - 1) = (uintptr_t)rop_get_arg;
+
+  if (ptrace(PTRACE_TRACEME, 0, 0, 0) == -1) {
+    tea_key[0] ^= 0x02020202;
+    tea_key[1] ^= 0x02020202;
+    tea_key[2] ^= 0x02020202;
+    tea_key[3] ^= 0x02020202;
+  }
+
+  static const unsigned char cipher[80] = {
+      '\x51', '\x54', '\x7C', '\x65', '\xEC', '\x8B', '\x27', '\xFF', '\xD7',
+      '\x4F', '\xDA', '\xA2', '\xD1', '\x91', '\x63', '\x8A', '\x45', '\x78',
+      '\xE8', '\x44', '\xC4', '\xA8', '\x18', '\x5D', '\x91', '\x4F', '\xCD',
+      '\xFF', '\xE0', '\x5B', '\x4B', '\x81', '\x59', '\x00', '\xFB', '\x69',
+      '\x72', '\xD2', '\xAB', '\x72', '\xF7', '\xA8', '\x9F', '\x40', '\x21',
+      '\x9C', '\xC4', '\x8F', '\x54', '\x89', '\xAB', '\x4D', '\xBA', '\x9B',
+      '\x3B', '\x8A', '\x33', '\x61', '\xDB', '\xD3', '\x8D', '\x23', '\x14',
+      '\xCF', '\xAE', '\xD0', '\x6B', '\x26', '\x2D', '\x8E', '\x73', '\xC4',
+      '\xFF', '\x6C', '\xAA', '\x18', '\x53', '\x0E', '\x85', '\x38'};
+
+  if (key == NULL || ((struct clone_args *)key)->decoy_key == NULL ||
+      ((struct clone_args *)key)->argv == NULL) {
+    return -1;
+  }
+
+  AES_KEY dec_key;
+  unsigned char plain[17] = {0};
+
+  if (AES_set_decrypt_key(((struct clone_args *)key)->decoy_key, 128,
+                          &dec_key) != 0) {
+    return -1;
+  }
+
+  for (int i = 0; i < 5; i++) {
+    AES_decrypt(cipher + 16 * i, plain, &dec_key);
+    printf("%s", plain);
+  }
+
+  printf("\n");
+
+  return 0;
+}
+
+uint32_t tmp[4];
+
+int flag_3(void *key) {
+  *(uintptr_t *)(&key - 1) = (uintptr_t)rop_get_arg;
+
+  static const unsigned char cipher[80] = {
+      '\xF9', '\x19', '\x1F', '\x45', '\x8D', '\xCB', '\x5F', '\x8C', '\x01',
+      '\x0A', '\x8B', '\x76', '\xFD', '\xD6', '\x2E', '\x2D', '\x47', '\x4D',
+      '\xA0', '\x7F', '\x48', '\x52', '\xF7', '\xD2', '\x3C', '\x07', '\xB0',
+      '\xC7', '\x72', '\x5B', '\xA5', '\x72', '\xA7', '\xC2', '\x0C', '\x77',
+      '\xA1', '\x79', '\xC2', '\x10', '\x42', '\xE1', '\x45', '\x0A', '\xFD',
+      '\xAD', '\x10', '\xF7', '\x8F', '\x56', '\x8E', '\x85', '\xC1', '\x7F',
+      '\x89', '\x3A', '\x8E', '\x85', '\x4F', '\xE2', '\x2E', '\x8B', '\xD0',
+      '\x01', '\xCB', '\x0C', '\x13', '\x46', '\xBF', '\x1C', '\x01', '\x9B',
+      '\x2C', '\x7F', '\x48', '\x99', '\xA7', '\xEA', '\x56', '\xB4'};
+
+  if (key == NULL || ((struct clone_args *)key)->decoy_key == NULL ||
+      ((struct clone_args *)key)->argv == NULL) {
+    return -1;
+  }
+
+  AES_KEY dec_key;
+  unsigned char plain[17] = {0};
+
+  if (AES_set_decrypt_key(((struct clone_args *)key)->decoy_key, 128,
+                          &dec_key) != 0) {
+    return -1;
+  }
+
+  for (int i = 0; i < 5; i++) {
+    AES_decrypt(cipher + 16 * i, plain, &dec_key);
+    printf("%s", plain);
+  }
+
+  printf("\n");
+
+  return 0;
+}
+
+__attribute__((constructor)) void create() {
+  if (stack != NULL) {
+    return;
+  }
+
+  stack = calloc(stack_size, 1);
+
+  if (stack == NULL) {
+    return;
+  }
+
+  uintptr_t *stack_flag_0 = (stack + stack_size - 0x1000 - 0x0C);
+
+  stack_flag_0[0] = 0;
+  stack_flag_0[1] = 1;
+  stack_flag_0[2] = 2;
+  stack_flag_0[3] = 3;
+  stack_flag_0[4] = 4;
+  stack_flag_0[5] = (uintptr_t)rop_flag_0_0;
+  stack_flag_0[6] = (uintptr_t)rop_exit;
+  stack_flag_0[7] = (uintptr_t)rop_flag_0_1;
+  stack_flag_0[8] = 0x466C7578;
+  stack_flag_0[9] = 0x78756C46;
+  stack_flag_0[10] = 0x466C7578;
+  stack_flag_0[11] = 0x210D191E;
+  stack_flag_0[12] = 0;
+  stack_flag_0[13] = 1;
+  stack_flag_0[14] = 2;
+  stack_flag_0[15] = 3;
+  stack_flag_0[16] = 4;
+  stack_flag_0[17] = (uintptr_t)rop_flag_0_2;
+  stack_flag_0[18] = (uintptr_t)rop_exit;
+  stack_flag_0[19] = 0x78756C46;
+  stack_flag_0[20] = 0x4B1D383D;
+  stack_flag_0[21] = 4;
+  stack_flag_0[22] = 8;
+  stack_flag_0[23] = 3;
+  stack_flag_0[24] = 0;
+  stack_flag_0[25] = 7;
+  stack_flag_0[26] = (uintptr_t)rop_exit;
+  stack_flag_0[27] = (uintptr_t)strlen;
+  stack_flag_0[28] = (uintptr_t)rop_copy_correct_flag;
+  stack_flag_0[29] = (uintptr_t)flag;
+  stack_flag_0[30] = 100;
+  stack_flag_0[31] = (uintptr_t)strncpy;
+  stack_flag_0[32] = (uintptr_t)rop_exit;
+  stack_flag_0[33] = (uintptr_t)flag;
+  // &"flag{Th3" (argv)
+  // sizeof(flag) - strlen(flag)
+
+  uintptr_t *stack_flag_1 = (stack + stack_size - 0x2000 - 0x0C);
+
+  stack_flag_1[0] = 0;
+  stack_flag_1[1] = 0x1C;
+  stack_flag_1[2] = 0xFFFFFFFC;
+  stack_flag_1[3] = 3;
+  stack_flag_1[4] = 4;
+  stack_flag_1[5] = (uintptr_t)rop_flag_1_0;
+  stack_flag_1[6] = (uintptr_t)rop_exit;
+  stack_flag_1[7] = (uintptr_t)strcpy;
+  stack_flag_1[8] = (uintptr_t)rop_flag_1_1;
+  // &(stack_flag_1[400])
+  // &"_key_1s_in_th3_secret_com" (argv)
+  stack_flag_1[11] = (uintptr_t)strlen;
+  stack_flag_1[12] = (uintptr_t)rop_flag_1_2;
+  // &"_key_1s_in_th3_secret_com" (argv)
+  stack_flag_1[14] = (uintptr_t)rop_flag_1_3;
+  stack_flag_1[15] = 0xFFFFFFFC;
+  stack_flag_1[16] = (uintptr_t)rop_flag_1_4;
+  stack_flag_1[17] = 8;
+  stack_flag_1[18] = (uintptr_t)rop_flag_1_5;
+  stack_flag_1[19] = 0x41;
+  stack_flag_1[20] = (uintptr_t)rop_flag_1_6;
+  stack_flag_1[21] = (uintptr_t)rop_flag_1_7;
+  stack_flag_1[22] = (uintptr_t)rop_flag_1_8;
+  stack_flag_1[23] = (uintptr_t)rop_flag_1_9;
+  stack_flag_1[24] = (uintptr_t)rop_flag_1_10;
+  stack_flag_1[25] = (uintptr_t)rop_flag_1_11;
+  stack_flag_1[26] = (uintptr_t)rop_flag_1_12;
+  stack_flag_1[27] = (uintptr_t)rop_flag_1_13;
+  stack_flag_1[28] = (uintptr_t)rop_flag_1_14;
+  stack_flag_1[29] = (uintptr_t)rop_flag_2_2;
+  stack_flag_1[30] = 4;
+  stack_flag_1[31] = 8;
+  stack_flag_1[32] = 3;
+  stack_flag_1[33] = 0;
+  stack_flag_1[34] = 7;
+  stack_flag_1[35] = (uintptr_t)rop_exit;
+  stack_flag_1[36] = (uintptr_t)strlen;
+  stack_flag_1[37] = (uintptr_t)rop_copy_correct_flag;
+  stack_flag_1[38] = (uintptr_t)flag;
+  stack_flag_1[39] = 100;
+  stack_flag_1[40] = (uintptr_t)strncpy;
+  stack_flag_1[41] = (uintptr_t)rop_exit;
+  stack_flag_1[42] = (uintptr_t)flag;
+
+  stack_flag_1[500] = 0x37D02C61;
+  stack_flag_1[501] = 0x63979F3B;
+  stack_flag_1[502] = 0xD07E4607;
+  stack_flag_1[503] = 0xAD79934A;
+  stack_flag_1[504] = 0xDDBDBBCA;
+  stack_flag_1[505] = 0x64A669E7;
+  stack_flag_1[506] = 0x68;
+
+  uintptr_t *stack_flag_2 = (stack + stack_size - 0x3000 - 0x0C);
+
+  stack_flag_2[0] = 0;
+  stack_flag_2[1] = 1;
+  stack_flag_2[2] = 2;
+  stack_flag_2[3] = 3;
+  stack_flag_2[4] = 4;
+  stack_flag_2[5] = (uintptr_t)rop_flag_2_0;
+  stack_flag_2[6] = (uintptr_t)rop_exit;
+  stack_flag_2[7] = (uintptr_t)MD5;
+  stack_flag_2[8] = (uintptr_t)rop_flag_2_1;
+  // &"p4rtme" (argv)
+  stack_flag_2[10] = 6;
+  // &md5_result
+  stack_flag_2[12] = 0xF46F4D7B;
+  stack_flag_2[13] = 0x3F6CC46A;
+  stack_flag_2[14] = 0x93CC8A62;
+  stack_flag_2[15] = 0x817D930D;
+  stack_flag_2[16] = (uintptr_t)rop_flag_2_2;
+  stack_flag_2[17] = 0x757960e1;
+  stack_flag_2[18] = 0x17733c32;
+  stack_flag_2[19] = 0x1ed9caff;
+  stack_flag_2[20] = 0xbc6a393e;
+  stack_flag_2[21] = 4;
+  stack_flag_2[22] = 8;
+  stack_flag_2[23] = 3;
+  stack_flag_2[24] = 0;
+  stack_flag_2[25] = 7;
+  stack_flag_2[26] = (uintptr_t)rop_exit;
+  stack_flag_2[27] = (uintptr_t)strlen;
+  stack_flag_2[28] = (uintptr_t)rop_copy_correct_flag;
+  stack_flag_2[29] = (uintptr_t)flag;
+  stack_flag_2[30] = 100;
+  stack_flag_2[31] = (uintptr_t)strncpy;
+  stack_flag_2[32] = (uintptr_t)rop_exit;
+  stack_flag_2[33] = (uintptr_t)flag;
+
+  uintptr_t *stack_flag_3 = (stack + stack_size - 0x4000 - 0x0C);
+
+  stack_flag_3[0] = 0;
+  stack_flag_3[1] = 1;
+  stack_flag_3[2] = 2;
+  stack_flag_3[3] = 3;
+  stack_flag_3[4] = 4;
+  stack_flag_3[5] = (uintptr_t)rop_flag_3_tea_init_0;
+  stack_flag_3[6] = (uintptr_t)rop_exit;
+  stack_flag_3[7] = (uintptr_t)(flag + 49);
+  stack_flag_3[8] = 0;
+  stack_flag_3[9] = (uintptr_t)rop_flag_3_tea_add_delta_to_sum;
+  stack_flag_3[10] = 0x9e3779b8;
+  stack_flag_3[11] = (uintptr_t)rop_flag_3_tea_v1_shl;
+  stack_flag_3[12] = (uintptr_t)rop_flag_3_tea_add_k0;
+  stack_flag_3[13] = (uintptr_t) & (tea_key[0]);
+  stack_flag_3[14] = (uintptr_t)rop_flag_3_tea_add_sum;
+  stack_flag_3[15] = (uintptr_t)rop_flag_3_tea_1st_xor;
+  stack_flag_3[16] = (uintptr_t)rop_flag_3_tea_v1_shr;
+  stack_flag_3[17] = (uintptr_t)rop_flag_3_tea_add_k1_or_k3;
+  stack_flag_3[18] = (uintptr_t) & (tea_key[1]);
+  stack_flag_3[19] = (uintptr_t)rop_flag_3_tea_2nd_and_4th_xor;
+  stack_flag_3[20] = (uintptr_t)rop_flag_3_tea_add_to_v0;
+  stack_flag_3[21] = (uintptr_t)rop_flag_3_tea_v1_shl;
+  stack_flag_3[22] = (uintptr_t)rop_flag_3_tea_add_k2;
+  stack_flag_3[23] = (uintptr_t) & (tea_key[2]);
+  stack_flag_3[24] = (uintptr_t)rop_flag_3_tea_add_sum;
+  stack_flag_3[25] = (uintptr_t)rop_flag_3_tea_3rd_xor;
+  stack_flag_3[26] = (uintptr_t)rop_flag_3_tea_v1_shr;
+  stack_flag_3[27] = (uintptr_t)rop_flag_3_tea_add_k1_or_k3;
+  stack_flag_3[28] = (uintptr_t) & (tea_key[3]);
+  stack_flag_3[29] = (uintptr_t)rop_flag_3_tea_2nd_and_4th_xor;
+  stack_flag_3[30] = (uintptr_t)rop_flag_3_tea_add_to_v1;
+  stack_flag_3[31] = (uintptr_t)rop_flag_3_tea_loop_tail;
+  stack_flag_3[32] = (uintptr_t)(flag + 49);
+  stack_flag_3[33] = 31;
+  stack_flag_3[34] = 0x6C;
+  stack_flag_3[35] = 0;
+  stack_flag_3[36] = (uintptr_t)rop_flag_3_check_tea;
+  stack_flag_3[37] = 0xA42D6EBF;
+  stack_flag_3[38] = 0x0EFE89E7;
+
+  stack_flag_3[39] = (uintptr_t)rop_exit;
+  stack_flag_3[40] = (uintptr_t)rop_flag_3_tea_init_1;
+  stack_flag_3[41] = (uintptr_t)(flag + 49);
+  stack_flag_3[42] = (uintptr_t)rop_flag_3_tea_add_delta_to_sum;
+  stack_flag_3[43] = 0x9e3779b8;
+  stack_flag_3[44] = (uintptr_t)rop_flag_3_tea_v1_shl;
+  stack_flag_3[45] = (uintptr_t)rop_flag_3_tea_add_k0;
+  stack_flag_3[46] = (uintptr_t) & (tea_key[0]);
+  stack_flag_3[47] = (uintptr_t)rop_flag_3_tea_add_sum;
+  stack_flag_3[48] = (uintptr_t)rop_flag_3_tea_1st_xor;
+  stack_flag_3[49] = (uintptr_t)rop_flag_3_tea_v1_shr;
+  stack_flag_3[50] = (uintptr_t)rop_flag_3_tea_add_k1_or_k3;
+  stack_flag_3[51] = (uintptr_t) & (tea_key[1]);
+  stack_flag_3[52] = (uintptr_t)rop_flag_3_tea_2nd_and_4th_xor;
+  stack_flag_3[53] = (uintptr_t)rop_flag_3_tea_add_to_v0;
+  stack_flag_3[54] = (uintptr_t)rop_flag_3_tea_v1_shl;
+  stack_flag_3[55] = (uintptr_t)rop_flag_3_tea_add_k2;
+  stack_flag_3[56] = (uintptr_t) & (tea_key[2]);
+  stack_flag_3[57] = (uintptr_t)rop_flag_3_tea_add_sum;
+  stack_flag_3[58] = (uintptr_t)rop_flag_3_tea_3rd_xor;
+  stack_flag_3[59] = (uintptr_t)rop_flag_3_tea_v1_shr;
+  stack_flag_3[60] = (uintptr_t)rop_flag_3_tea_add_k1_or_k3;
+  stack_flag_3[61] = (uintptr_t) & (tea_key[3]);
+  stack_flag_3[62] = (uintptr_t)rop_flag_3_tea_2nd_and_4th_xor;
+  stack_flag_3[63] = (uintptr_t)rop_flag_3_tea_add_to_v1;
+  stack_flag_3[64] = (uintptr_t)rop_flag_3_tea_loop_tail;
+  stack_flag_3[65] = (uintptr_t)(flag + 49);
+  stack_flag_3[66] = 31;
+  stack_flag_3[67] = 0x6C;
+  stack_flag_3[68] = 0;
+  stack_flag_3[69] = (uintptr_t)rop_flag_3_check_tea;
+  stack_flag_3[70] = 0xAADD934D;
+  stack_flag_3[71] = 0x4E4E7F13;
+
+  stack_flag_3[72] = (uintptr_t)rop_exit;
+  stack_flag_3[73] = (uintptr_t)rop_flag_3_tea_init_2;
+  stack_flag_3[74] = (uintptr_t)(flag + 49);
+  stack_flag_3[75] = (uintptr_t)rop_flag_3_tea_add_delta_to_sum;
+  stack_flag_3[76] = 0x9e3779b8;
+  stack_flag_3[77] = (uintptr_t)rop_flag_3_tea_v1_shl;
+  stack_flag_3[78] = (uintptr_t)rop_flag_3_tea_add_k0;
+  stack_flag_3[79] = (uintptr_t) & (tea_key[0]);
+  stack_flag_3[80] = (uintptr_t)rop_flag_3_tea_add_sum;
+  stack_flag_3[81] = (uintptr_t)rop_flag_3_tea_1st_xor;
+  stack_flag_3[82] = (uintptr_t)rop_flag_3_tea_v1_shr;
+  stack_flag_3[83] = (uintptr_t)rop_flag_3_tea_add_k1_or_k3;
+  stack_flag_3[84] = (uintptr_t) & (tea_key[1]);
+  stack_flag_3[85] = (uintptr_t)rop_flag_3_tea_2nd_and_4th_xor;
+  stack_flag_3[86] = (uintptr_t)rop_flag_3_tea_add_to_v0;
+  stack_flag_3[87] = (uintptr_t)rop_flag_3_tea_v1_shl;
+  stack_flag_3[88] = (uintptr_t)rop_flag_3_tea_add_k2;
+  stack_flag_3[89] = (uintptr_t) & (tea_key[2]);
+  stack_flag_3[90] = (uintptr_t)rop_flag_3_tea_add_sum;
+  stack_flag_3[91] = (uintptr_t)rop_flag_3_tea_3rd_xor;
+  stack_flag_3[92] = (uintptr_t)rop_flag_3_tea_v1_shr;
+  stack_flag_3[93] = (uintptr_t)rop_flag_3_tea_add_k1_or_k3;
+  stack_flag_3[94] = (uintptr_t) & (tea_key[3]);
+  stack_flag_3[95] = (uintptr_t)rop_flag_3_tea_2nd_and_4th_xor;
+  stack_flag_3[96] = (uintptr_t)rop_flag_3_tea_add_to_v1;
+  stack_flag_3[97] = (uintptr_t)rop_flag_3_tea_loop_tail;
+  stack_flag_3[98] = (uintptr_t)(flag + 49);
+  stack_flag_3[99] = 31;
+  stack_flag_3[100] = 0x6C;
+  stack_flag_3[101] = 0;
+  stack_flag_3[102] = (uintptr_t)rop_flag_3_check_tea;
+  stack_flag_3[103] = 0x8EC32CA9;
+  stack_flag_3[104] = 0x8559D4E9;
+
+  stack_flag_3[105] = (uintptr_t)rop_exit;
+  stack_flag_3[106] = (uintptr_t)strlen;
+  stack_flag_3[107] = (uintptr_t)rop_copy_correct_flag;
+  stack_flag_3[108] = (uintptr_t)flag;
+  stack_flag_3[109] = 100;
+  stack_flag_3[110] = (uintptr_t)strncpy;
+  stack_flag_3[111] = (uintptr_t)rop_exit;
+  stack_flag_3[112] = (uintptr_t)flag;
+}
+
+__attribute__((destructor)) void destroy() {
+  if (stack != NULL) {
+    free(stack);
+  }
+}
diff --git a/md5_hash.txt b/md5_hash.txt
new file mode 100644
index 0000000..d6dd48f
--- /dev/null
+++ b/md5_hash.txt
@@ -0,0 +1 @@
+7b4d6ff46ac46c3f628acc930d937d81
\ No newline at end of file
diff --git a/notes.txt b/notes.txt
new file mode 100644
index 0000000..92ebce8
--- /dev/null
+++ b/notes.txt
@@ -0,0 +1,23 @@
+Useful for debugging with gdb:
+    
+    set follow-fork-mode child
+    set detach-on-fork off
+
+    info inferiors
+    inferior infno
+
+
+Hashcat for the 3rd argument:
+    
+    hashcat -m 0 -a 3 md5_hash.txt \?a\?a\?a\?a\?a\?a
+
+
+LostKey with correct arguments:
+    ./LostKey flag{Th3 _key_1s_in_th3_secret_com p4rtme $(python2 -c "print 'nt_of_your_t00l_sh3d...}'")
+
+
+My zsh complains about
+    zsh: no matches found: ?a?a?a?a?a?a
+and
+    zsh: parse error near `}'
+:/
\ No newline at end of file
diff --git a/rop.c b/rop.c
new file mode 100644
index 0000000..ea686cf
--- /dev/null
+++ b/rop.c
@@ -0,0 +1,462 @@
+#include "rop.h"
+
+__attribute__((naked)) void rop_exit() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "mov eax, 0x1\n"
+      "call dword ptr gs:0x10");
+}
+
+__attribute__((naked)) void rop_get_arg() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop ebp\n"
+      "cmp eax, 0\n"
+      "cmove ebp, [ebp+4]\n"
+      "pop eax\n"
+      "pop esi\n"
+      "pop edi\n"
+      "pop edx\n"
+      "pop ebx\n"
+      "cmovne eax, ebx\n"
+      "add eax, esp\n"
+      "xchg eax, esp\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_0_0() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "mov eax, [ebp]\n"
+      "pop edx\n"
+      "retn 8");
+}
+
+__attribute__((naked)) void rop_flag_0_1() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop ebx\n"
+      "xor eax, ebx\n"
+      "pop ebx\n"
+      "cmp eax, ebx\n"
+      "pop esi\n"
+      "pop edi\n"
+      "pop edx\n"
+      "pop eax\n"
+      "pop ebx\n"
+      "cmovne esi, ebx\n"
+      "add esi, esp\n"
+      "xchg esi, esp\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_0_2() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "mov eax, [ebp+4]\n"
+      "pop esi\n"
+      "pop ebx\n"
+      "xor eax, ebx\n"
+      "pop ebx\n"
+      "cmp eax, ebx\n"
+      "pop eax\n"
+      "pop esi\n"
+      "pop edi\n"
+      "pop edx\n"
+      "pop ebx\n"
+      "cmove edx, eax\n"
+      "add edx, esp\n"
+      "xchg edx, esp\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_copy_correct_flag() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop ecx\n"
+      "add ecx, eax\n"
+      "mov [esp+0xC], ecx\n"
+      "pop edx\n"
+      "sub edx, eax\n"
+      "mov [esp+0x10], edx\n"
+      "mov [esp+0xC], ebp\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_0() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop edx\n"
+      "mov ecx, esp\n"
+      "add ecx, 0x624\n"
+      "mov [esp+8], ecx\n"
+      "mov [esp+0xC], ebp\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_1() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop ebx\n"
+      "pop ecx\n"
+      "sub eax, ecx\n"
+      "cmp eax, ebx\n"
+      "cmovg eax, edx\n"
+      "mov [esp+8], ebp\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_2() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "cmp eax, 1\n"
+      "cmovle edi, esi\n"
+      "sub esp, edi\n"
+      "retn 4");
+}
+
+__attribute__((naked)) void rop_flag_1_3() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "dec eax\n"
+      "xor ebx, ebx\n"
+      "mov esi, ebp\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_4() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "movzx edx, byte ptr [esi]\n"
+      "not edx\n"
+      "movzx edx, dl\n"
+      "mov ecx, edx\n"
+      "shl edx, 4\n"
+      "shr ecx, 4\n"
+      "or edx, ecx\n"
+      "mov [esi], dl\n"
+      "movzx edx, byte ptr [esi+1]\n"
+      "xor [esi], dl\n"
+      "inc ebx\n"
+      "pop edi\n"
+      "xor edx, edx\n"
+      "cmp ebx, eax\n"
+      "cmovl edx, edi\n"
+      "sub esp, edx\n"
+      "inc esi\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_5() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "movzx edx, byte ptr [esi]\n"
+      "not edx\n"
+      "movzx edx, dl\n"
+      "mov ecx, edx\n"
+      "shl edx, 4\n"
+      "shr ecx, 4\n"
+      "or edx, ecx\n"
+      "mov [esi], dl\n"
+      "pop edx\n"
+      "xor [esi], dl\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_6() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "xor ecx, ecx\n"
+      "mov ebx, [ebp]\n"
+      "cmp ebx, [esp+0x77C]\n"
+      "setne cl\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_7() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "mov ebx, [ebp+4]\n"
+      "cmp ebx, [esp+0x77C]\n"
+      "setne cl\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_8() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "mov ebx, [ebp+8]\n"
+      "cmp ebx, [esp+0x77C]\n"
+      "setne cl\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_9() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "mov ebx, [ebp+0xC]\n"
+      "cmp ebx, [esp+0x77C]\n"
+      "setne cl\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_10() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "mov ebx, [ebp+0x10]\n"
+      "cmp ebx, [esp+0x77C]\n"
+      "setne cl\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_11() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "mov ebx, [ebp+0x14]\n"
+      "cmp ebx, [esp+0x77C]\n"
+      "setne cl\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_12() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "movzx ebx, byte ptr [ebp+0x18]\n"
+      "cmp ebx, [esp+0x77C]\n"
+      "setne cl\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_13() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "mov ebp, esp\n"
+      "add ebp, 0x5D0\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_1_14() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "cmp ecx, 0\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_2_0() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop edx\n"
+      "lea eax, [esp+0x250]\n"
+      "mov [esp+8], ebp\n"
+      "mov [esp+0x10], eax\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_2_1() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "add esp, 0xC\n"
+      "xor edx, edx\n"
+      "pop esi\n"
+      "cmp esi, [esp+0x238]\n"
+      "setne dl\n"
+      "pop esi\n"
+      "cmp esi, [esp+0x238]\n"
+      "setne dl\n"
+      "pop esi\n"
+      "cmp esi, [esp+0x238]\n"
+      "setne dl\n"
+      "pop esi\n"
+      "cmp esi, [esp+0x238]\n"
+      "setne dl\n"
+      "cmp edx, 0\n"
+      "ret 0x10");
+}
+
+__attribute__((naked)) void rop_flag_2_2() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop eax\n"
+      "pop esi\n"
+      "pop edi\n"
+      "pop edx\n"
+      "pop ebx\n"
+      "cmove edx, eax\n"
+      "add edx, esp\n"
+      "xchg edx, esp\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_init_0() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop edx\n"
+      "xor eax, eax\n"
+      "pop ecx\n"
+      "mov byte ptr [ecx], al\n"
+      "pop ebx\n"
+      "mov edi, [ebp]\n"
+      "mov esi, [ebp+4]\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_init_1() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "xor eax, eax\n"
+      "pop ebx\n"
+      "mov byte ptr [ebx], al\n"
+      "xor ebx, ebx\n"
+      "mov edi, [ebp+8]\n"
+      "mov esi, [ebp+0xC]\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_init_2() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "xor eax, eax\n"
+      "pop edx\n"
+      "mov byte ptr [edx], al\n"
+      "xor ebx, ebx\n"
+      "mov edi, [ebp+0x10]\n"
+      "mov esi, [ebp+0x14]\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_add_delta_to_sum() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop ecx\n"
+      "inc ecx\n"
+      "add ebx, ecx\n"
+      "mov ecx, esi\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_v1_shl() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "shl ecx, 4\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_add_k0() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop eax\n"
+      "mov eax, [eax]\n"
+      "add ecx, eax\n"
+      "mov edx, esi\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_add_sum() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "add edx, ebx\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_1st_xor() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "xor ecx, edx\n"
+      "mov edx, esi\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_v1_shr() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "shr edx, 5\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_add_k1_or_k3() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop eax\n"
+      "mov eax, [eax]\n"
+      "add edx, eax\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_2nd_and_4th_xor() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "xor ecx, edx\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_add_to_v0() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "add edi, ecx\n"
+      "mov ecx, edi\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_add_k2() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop eax\n"
+      "mov eax, [eax]\n"
+      "add ecx, eax\n"
+      "mov edx, edi\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_3rd_xor() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "xor ecx, edx\n"
+      "mov edx, edi\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_add_to_v1() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "add esi, ecx\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_tea_loop_tail() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop ecx\n"
+      "xor eax, eax\n"
+      "mov al, byte ptr [ecx]\n"
+      "inc eax\n"
+      "mov byte ptr [ecx], al\n"
+      "pop edx\n"
+      "cmp eax, edx\n"
+      "pop ecx\n"
+      "pop edx\n"
+      "cmovbe edx, ecx\n"
+      "sub esp, edx\n"
+      "ret");
+}
+
+__attribute__((naked)) void rop_flag_3_check_tea() {
+  __asm__ volatile(
+      ".intel_syntax noprefix\n"
+      "pop ecx\n"
+      "xor eax, eax\n"
+      "cmp edi, ecx\n"
+      "setne al\n"
+      "pop ecx\n"
+      "cmp esi, ecx\n"
+      "setne al\n"
+      "xor ebx, ebx\n"
+      "inc ebx\n"
+      "inc ebx\n"
+      "inc ebx\n"
+      "inc ebx\n"
+      "xor ecx, ecx\n"
+      "cmp eax, ecx\n"
+      "cmove ecx, ebx\n"
+      "add esp, ecx\n"
+      "ret");
+}
diff --git a/rop.h b/rop.h
new file mode 100644
index 0000000..84b2e96
--- /dev/null
+++ b/rop.h
@@ -0,0 +1,52 @@
+#ifndef ROP_H_
+#define ROP_H_
+
+void rop_exit() __attribute__((naked));
+
+void rop_get_arg() __attribute__((naked));
+
+void rop_copy_correct_flag() __attribute__((naked));
+
+void rop_flag_0_0() __attribute__((naked));
+void rop_flag_0_1() __attribute__((naked));
+void rop_flag_0_2() __attribute__((naked));
+
+void rop_flag_1_0() __attribute__((naked));
+void rop_flag_1_1() __attribute__((naked));
+void rop_flag_1_2() __attribute__((naked));
+void rop_flag_1_3() __attribute__((naked));
+void rop_flag_1_4() __attribute__((naked));
+void rop_flag_1_5() __attribute__((naked));
+void rop_flag_1_6() __attribute__((naked));
+void rop_flag_1_7() __attribute__((naked));
+void rop_flag_1_8() __attribute__((naked));
+void rop_flag_1_9() __attribute__((naked));
+void rop_flag_1_10() __attribute__((naked));
+void rop_flag_1_11() __attribute__((naked));
+void rop_flag_1_12() __attribute__((naked));
+void rop_flag_1_13() __attribute__((naked));
+void rop_flag_1_14() __attribute__((naked));
+
+void rop_flag_2_0() __attribute__((naked));
+void rop_flag_2_1() __attribute__((naked));
+void rop_flag_2_2() __attribute__((naked));
+
+void rop_flag_3_tea_init_0() __attribute__((naked));
+void rop_flag_3_tea_init_1() __attribute__((naked));
+void rop_flag_3_tea_init_2() __attribute__((naked));
+void rop_flag_3_tea_add_delta_to_sum() __attribute__((naked));
+void rop_flag_3_tea_v1_shl() __attribute__((naked));
+void rop_flag_3_tea_add_k0() __attribute__((naked));
+void rop_flag_3_tea_add_sum() __attribute__((naked));
+void rop_flag_3_tea_1st_xor() __attribute__((naked));
+void rop_flag_3_tea_v1_shr() __attribute__((naked));
+void rop_flag_3_tea_add_k1_or_k3() __attribute__((naked));
+void rop_flag_3_tea_2nd_and_4th_xor() __attribute__((naked));
+void rop_flag_3_tea_add_to_v0() __attribute__((naked));
+void rop_flag_3_tea_add_k2() __attribute__((naked));
+void rop_flag_3_tea_3rd_xor() __attribute__((naked));
+void rop_flag_3_tea_add_to_v1() __attribute__((naked));
+void rop_flag_3_tea_loop_tail() __attribute__((naked));
+void rop_flag_3_check_tea() __attribute__((naked));
+
+#endif  // ROP_H_
diff --git a/rop_in_c.c b/rop_in_c.c
new file mode 100644
index 0000000..75de723
--- /dev/null
+++ b/rop_in_c.c
@@ -0,0 +1,116 @@
+/*
+ * gcc -static -m32 rop_in_c.c -L openssl-1.1.0f -l:libcrypto.a
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "openssl/md5.h"
+
+void stringFlag1EncDec(uint32_t *string) {
+  string[0] = string[0] ^ 0x466C7578;
+  string[1] = string[1] ^ 0x78756C46;
+}
+
+void stringFlag2Enc(char *_string) {
+  uint8_t *string = (uint8_t *)_string;
+  uint8_t tmp;
+  int length = strlen(_string);
+
+  if (length < 2) {
+    return;
+  }
+
+  for (int i = 0; i < length - 1; i++) {
+    tmp = ~string[i];
+    tmp = (tmp << 4) | (tmp >> 4);
+    tmp ^= string[i + 1];
+    string[i] = tmp;
+  }
+
+  tmp = ~string[length - 1];
+  tmp = (tmp << 4) | (tmp >> 4);
+  tmp ^= 0x41;
+  string[length - 1] = tmp;
+}
+
+void stringFlag2Dec(char *_string) {
+  uint8_t *string = (uint8_t *)_string;
+  uint8_t tmp;
+  int length = strlen(_string);
+
+  if (length < 2) {
+    return;
+  }
+
+  tmp = string[length - 1];
+  tmp ^= 0x41;
+  tmp = (tmp << 4) | (tmp >> 4);
+  string[length - 1] = ~tmp;
+
+  for (int i = length - 2; i >= 0; i--) {
+    tmp = string[i];
+    tmp ^= string[i + 1];
+    tmp = (tmp << 4) | (tmp >> 4);
+    string[i] = ~tmp;
+  }
+}
+
+// From https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm
+void encrypt(uint32_t *v, uint32_t *k) {
+  uint32_t v0 = v[0], v1 = v[1], sum = 0, i; /* set up */
+  uint32_t delta = 0x9e3779b9;               /* a key schedule constant */
+  uint32_t k0 = k[0], k1 = k[1], k2 = k[2], k3 = k[3]; /* cache key */
+  for (i = 0; i < 32; i++) {                           /* basic cycle start */
+    sum += delta;
+    v0 += ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1);
+    v1 += ((v0 << 4) + k2) ^ (v0 + sum) ^ ((v0 >> 5) + k3);
+  } /* end cycle */
+  v[0] = v0;
+  v[1] = v1;
+}
+
+int main() {
+  char flag[] =
+      "flag{Th3_key_1s_in_th3_secret_comp4rtment_of_your_t00l_sh3d...}";
+  char flag1[] = "flag{Th3";
+  char flag2[] = "_key_1s_in_th3_secret_com";
+  char flag3[] = "p4rtme";
+  char flag4[] = "nt_of_your_t00l_sh3d...}";
+
+  unsigned char digest[MD5_DIGEST_LENGTH];
+  uint32_t tea_key[] = {0xC2E1FAFF, 0xFFFAE1C2, 0xFFFAE1C2, 0xC2E1FAFF};
+
+  stringFlag1EncDec((uint32_t *)flag1);
+  printf("Flag part 1: 0x%X 0x%X\n", *(uint32_t *)flag1,
+         *(uint32_t *)(flag1 + 4));
+
+  stringFlag1EncDec((uint32_t *)flag1);
+  printf("Flag part 1: %s\n", flag1);
+
+  stringFlag2Enc(flag2);
+  printf("Flag part 2: 0x%X 0x%X 0x%X 0x%X 0x%X 0x%X 0x%X\n",
+         *(uint32_t *)flag2, *(uint32_t *)(flag2 + 4), *(uint32_t *)(flag2 + 8),
+         *(uint32_t *)(flag2 + 12), *(uint32_t *)(flag2 + 16),
+         *(uint32_t *)(flag2 + 20), flag2[24] & 0xFF);
+
+  stringFlag2Dec(flag2);
+  printf("Flag part 2: %s\n", flag2);
+
+  MD5((unsigned char *)flag3, strlen(flag3), digest);
+  printf("Flag part 3: 0x%X 0x%X 0x%X 0x%X\n", *(uint32_t *)digest,
+         *(uint32_t *)(digest + 4), *(uint32_t *)(digest + 8),
+         *(uint32_t *)(digest + 12));
+
+  encrypt((uint32_t *)flag4, tea_key);
+  encrypt((uint32_t *)(flag4 + 8), tea_key);
+  encrypt((uint32_t *)(flag4 + 0x10), tea_key);
+
+  printf("Flag part 4: 0x%08X 0x%08X 0x%08X 0x%08X 0x%08X 0x%08X\n",
+         *(uint32_t *)flag4, *(uint32_t *)(flag4 + 4), *(uint32_t *)(flag4 + 8),
+         *(uint32_t *)(flag4 + 12), *(uint32_t *)(flag4 + 16),
+         *(uint32_t *)(flag4 + 20));
+
+  return 0;
+}
\ No newline at end of file