From b1d49d52356b1cb4f8bad99f6f565bbf75d4ee66 Mon Sep 17 00:00:00 2001
From: Dimitri Merejkowsky <dimitri.merejkowsky@tanker.io>
Date: Thu, 27 Jun 2019 12:00:01 +0200
Subject: [PATCH] stegano soluce

---
 sources/stegano/requirements.lock | 21 ++++++++
 sources/stegano/setup.cfg         | 24 +++++++++
 sources/stegano/setup.py          |  2 +
 sources/stegano/stegano.py        | 82 +++++++++++++++++++++++++++++++
 sources/stegano/test_stegano.py   |  9 ++++
 5 files changed, 138 insertions(+)
 create mode 100644 sources/stegano/requirements.lock
 create mode 100644 sources/stegano/setup.cfg
 create mode 100644 sources/stegano/setup.py
 create mode 100644 sources/stegano/stegano.py
 create mode 100644 sources/stegano/test_stegano.py

diff --git a/sources/stegano/requirements.lock b/sources/stegano/requirements.lock
new file mode 100644
index 0000000..d274567
--- /dev/null
+++ b/sources/stegano/requirements.lock
@@ -0,0 +1,21 @@
+# Generated with dmenv 0.15.0, python 3.7.1, on Linux
+appdirs==1.4.3
+atomicwrites==1.3.0
+attrs==19.1.0
+black==19.3b0
+Click==7.0
+importlib-metadata==0.18
+more-itertools==7.1.0
+packaging==19.0
+Pillow==6.0.0
+pip==19.1.1
+pluggy==0.12.0
+py==1.8.0
+pyparsing==2.4.0
+pytest==4.6.3
+setuptools==41.0.1
+six==1.12.0
+toml==0.10.0
+wcwidth==0.1.7
+wheel==0.33.4
+zipp==0.5.1
diff --git a/sources/stegano/setup.cfg b/sources/stegano/setup.cfg
new file mode 100644
index 0000000..0f130ea
--- /dev/null
+++ b/sources/stegano/setup.cfg
@@ -0,0 +1,24 @@
+[metadata]
+name = stegano
+version = 0.1.0
+description = simple steagography script
+author = e2l
+
+[options]
+py_modules = ["stegano"],
+
+install_requires =
+  Pillow
+
+classifiers =
+  "Programming Language :: Python :: 3"
+
+
+[options.extras_require]
+dev =
+  black
+  pytest
+
+[options.entry_points]
+console_scripts =
+   stegano = stegano:main
diff --git a/sources/stegano/setup.py b/sources/stegano/setup.py
new file mode 100644
index 0000000..8bf1ba9
--- /dev/null
+++ b/sources/stegano/setup.py
@@ -0,0 +1,2 @@
+from setuptools import setup
+setup()
diff --git a/sources/stegano/stegano.py b/sources/stegano/stegano.py
new file mode 100644
index 0000000..e3539a1
--- /dev/null
+++ b/sources/stegano/stegano.py
@@ -0,0 +1,82 @@
+import PIL.Image
+import itertools
+
+import sys
+
+
+def get_bitstream(message):
+    for c in message:
+        bin_string = "{:08b}".format(c)
+        for bit in bin_string:
+            yield int(bit)
+
+
+def parse_bitstream(stream):
+    for bits in by_chunk(stream, 8, fillvalue=0):
+        binstr = "".join([str(b) for b in bits])
+        c = int(binstr, 2)
+        if chr(c) == "\n":
+            break
+        yield c
+
+
+def by_chunk(iterable, size, fillvalue=0):
+    "Collect data into fixed-length chunks or blocks"
+    args = [iter(iterable)] * size
+    return itertools.zip_longest(*args, fillvalue=fillvalue)
+
+
+def set_bit(old_byte, new_bit):
+    b = list(bin(old_byte))
+    b[-1] = str(new_bit)
+    return int("".join(b), 2)
+
+
+def main_encrypt():
+    base_name = sys.argv[2]
+    message = (sys.argv[3] + "\n").encode()
+    carrier_name = base_name.replace(".png", ".carrier.png")
+    base_image = PIL.Image.open(base_name)
+    width, height = base_image.size
+    new_image = PIL.Image.new("RGB", (width, height), "white")
+    bitstream = get_bitstream(message)
+    for row in range(height):
+        for col in range(width):
+            r, g, b = base_image.getpixel((col, row))
+            value = None
+            try:
+                value = next(bitstream)
+            except StopIteration:
+                pass
+            if value is not None:
+                r = set_bit(r, value)
+            new_image.putpixel((col, row), (r, g, b))
+
+    new_image.save(carrier_name, "png")
+    print("carrier written to", carrier_name)
+
+
+def yield_bits(carrier_image):
+    width, height = carrier_image.size
+    for row in range(height):
+        for col in range(width):
+            r, g, b = carrier_image.getpixel((col, row))
+            last_bit = int(bin(r)[-1])
+            yield last_bit
+
+
+def main_decrypt():
+    carrier_name = sys.argv[2]
+    carrier_image = PIL.Image.open(carrier_name)
+    encoded = yield_bits(carrier_image)
+    decoded = bytes(parse_bitstream(encoded))
+    print(decoded.decode())
+
+
+def main():
+    if sys.argv[1] == "encrypt":
+        main_encrypt()
+    elif sys.argv[1] == "decrypt":
+        main_decrypt()
+    else:
+        sys.exit("choose from encrypt, decrypt")
diff --git a/sources/stegano/test_stegano.py b/sources/stegano/test_stegano.py
new file mode 100644
index 0000000..a23bf44
--- /dev/null
+++ b/sources/stegano/test_stegano.py
@@ -0,0 +1,9 @@
+import stegano
+
+
+def test_message_conversion():
+    message = b"I love you\ngarbage"
+    encoded = list(stegano.get_bitstream(message))
+
+    decoded = bytes(stegano.parse_bitstream(encoded))
+    assert decoded == b"I love you"