feat(wpcarro/scratch): Upload my solutions to picoCTF challenges r/3500

Just getting my feet wet...

Change-Id: Ia1db0c69fe7d5ea5cb5585853d0688ef97f2680a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/4739
Reviewed-by: wpcarro <wpcarro@gmail.com>
Autosubmit: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI

9 files changed, 107 insertions, 0 deletions

diff --git a/users/wpcarro/scratch/picoctf/.skip-subtree b/users/wpcarro/scratch/picoctf/.skip-subtree
new file mode 100644
index 000000000000..e69de29bb2d1
--- /dev/null
+++ b/users/wpcarro/scratch/picoctf/.skip-subtree
diff --git a/users/wpcarro/scratch/picoctf/README.md b/users/wpcarro/scratch/picoctf/README.md
new file mode 100644
index 000000000000..03a49817f745
--- /dev/null
+++ b/users/wpcarro/scratch/picoctf/README.md
@@ -0,0 +1,3 @@
+# picoCTF
+
+My solutions for some of the questsions at https://play.picoctf.org/practice.
diff --git a/users/wpcarro/scratch/picoctf/challenge_144.py b/users/wpcarro/scratch/picoctf/challenge_144.py
new file mode 100644
index 000000000000..570a7fd5a77b
--- /dev/null
+++ b/users/wpcarro/scratch/picoctf/challenge_144.py
@@ -0,0 +1,11 @@
+def rotate_alpha(x, n):
+    def rotate_char(c, n):
+        offset = 'A' if c.isupper() else 'a'
+        return chr((ord(c) - ord(offset) + n) % 26 + ord(offset))
+    return "".join([rotate_char(c, n) if c.isalpha() else c for c in x])
+
+xs = [
+    "cvpbPGS{arkg_gvzr_V'yy_gel_2_ebhaqf_bs_ebg13_Ncualgvd}",
+]
+for x in xs:
+    print(rotate_alpha(x, 13))
diff --git a/users/wpcarro/scratch/picoctf/challenge_156.py b/users/wpcarro/scratch/picoctf/challenge_156.py
new file mode 100644
index 000000000000..8c87a1ce7694
--- /dev/null
+++ b/users/wpcarro/scratch/picoctf/challenge_156.py
@@ -0,0 +1,13 @@
+bytestring = [
+    112, 105, 99, 111, 67, 84, 70, 123, 103, 48, 48, 100, 95, 107, 49, 116,
+    116, 121, 33, 95, 110, 49, 99, 51, 95, 107, 49, 116, 116, 121, 33, 95, 57,
+    98, 51, 98, 55, 51, 57, 50, 125, 10,
+]
+
+def decode(xs):
+    result = []
+    for x in xs:
+        result.append(chr(x))
+    return "".join(result)
+
+print(decode(bytestring))
diff --git a/users/wpcarro/scratch/picoctf/challenge_166/ende.py b/users/wpcarro/scratch/picoctf/challenge_166/ende.py
new file mode 100644
index 000000000000..08395f920909
--- /dev/null
+++ b/users/wpcarro/scratch/picoctf/challenge_166/ende.py
@@ -0,0 +1,60 @@
+
+import sys
+import base64
+from cryptography.fernet import Fernet
+
+
+
+usage_msg = "Usage: "+ sys.argv[0] +" (-e/-d) [file]"
+help_msg = usage_msg + "\n" +\
+        "Examples:\n" +\
+        "  To decrypt a file named 'pole.txt', do: " +\
+        "'$ python "+ sys.argv[0] +" -d pole.txt'\n"
+
+
+
+if len(sys.argv) < 2 or len(sys.argv) > 4:
+    print(usage_msg)
+    sys.exit(1)
+
+
+
+if sys.argv[1] == "-e":
+    if len(sys.argv) < 4:
+        sim_sala_bim = input("Please enter the password:")
+    else:
+        sim_sala_bim = sys.argv[3]
+
+    ssb_b64 = base64.b64encode(sim_sala_bim.encode())
+    c = Fernet(ssb_b64)
+
+    with open(sys.argv[2], "rb") as f:
+        data = f.read()
+        data_c = c.encrypt(data)
+        sys.stdout.write(data_c.decode())
+
+
+elif sys.argv[1] == "-d":
+    if len(sys.argv) < 4:
+        sim_sala_bim = input("Please enter the password:")
+    else:
+        sim_sala_bim = sys.argv[3]
+
+    ssb_b64 = base64.b64encode(sim_sala_bim.encode())
+    c = Fernet(ssb_b64)
+
+    with open(sys.argv[2], "r") as f:
+        data = f.read()
+        data_c = c.decrypt(data.encode())
+        sys.stdout.buffer.write(data_c)
+
+
+elif sys.argv[1] == "-h" or sys.argv[1] == "--help":
+    print(help_msg)
+    sys.exit(1)
+
+
+else:
+    print("Unrecognized first argument: "+ sys.argv[1])
+    print("Please use '-e', '-d', or '-h'.")
+
diff --git a/users/wpcarro/scratch/picoctf/challenge_166/flag.txt.en b/users/wpcarro/scratch/picoctf/challenge_166/flag.txt.en
new file mode 100644
index 000000000000..1c4d245811e8
--- /dev/null
+++ b/users/wpcarro/scratch/picoctf/challenge_166/flag.txt.en
@@ -0,0 +1 @@
+gAAAAABgUAIWsYfVayn4m1dKle5X91HrZW_MIRAW4ILPgf4gD6jalLF4PysYB5_YTpDwclcQPqw_0xTxanpJ_Urx5Vi6mTeBA_rWPA_WQLvVXXHp1mG3EpOgY8Na1_NIAfc9LceH_L2o
\ No newline at end of file
diff --git a/users/wpcarro/scratch/picoctf/challenge_166/pw.txt b/users/wpcarro/scratch/picoctf/challenge_166/pw.txt
new file mode 100644
index 000000000000..a4c1c7ae6631
--- /dev/null
+++ b/users/wpcarro/scratch/picoctf/challenge_166/pw.txt
@@ -0,0 +1 @@
+67c6cc9667c6cc9667c6cc9667c6cc96
diff --git a/users/wpcarro/scratch/picoctf/challenge_166/shell.nix b/users/wpcarro/scratch/picoctf/challenge_166/shell.nix
new file mode 100644
index 000000000000..07a3a2e281b4
--- /dev/null
+++ b/users/wpcarro/scratch/picoctf/challenge_166/shell.nix
@@ -0,0 +1,7 @@
+{ pkgs, ... }:
+
+let
+  python =pkgs.python3.withPackages (pypkgs: with pypkgs; [
+    cryptography
+  ]);
+in python.env
diff --git a/users/wpcarro/scratch/picoctf/challenge_170/README.md b/users/wpcarro/scratch/picoctf/challenge_170/README.md
new file mode 100644
index 000000000000..2507208f5c1a
--- /dev/null
+++ b/users/wpcarro/scratch/picoctf/challenge_170/README.md
@@ -0,0 +1,11 @@
+# challenge 170
+
+The following should work on most Linux distros, but it didn't for me on NixOS:
+
+```shell
+chmod u+x ./warm
+./warm -h
+```
+
+So instead, just call `strings` on the exectuable to search for the help text,
+which contains the flag.