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-rw-r--r--encrypt.py68
-rw-r--r--filecrypt.py71
-rw-r--r--server.py46
3 files changed, 124 insertions, 61 deletions
diff --git a/encrypt.py b/encrypt.py
index 162b6df..80cedf3 100644
--- a/encrypt.py
+++ b/encrypt.py
@@ -1,73 +1,19 @@
#!/usr/bin/env python3
-import secrets
-from Cryptodome.Cipher import AES
-import base64
-import struct
-import subprocess
-import binascii
+import os
-def encrypt_file(filename_in, chunk_size=1000000//16):
- file_id = secrets.token_urlsafe(22)
- auth_secret = secrets.token_bytes(16)
- key = secrets.token_bytes(16)
- data_nonce = secrets.token_bytes(8)
-
- token_cipher = AES.new(auth_secret, AES.MODE_GCM)
- ciphertext, token_tag = token_cipher.encrypt_and_digest(key)
- token = base64.b64encode(ciphertext)
-
- with open(f'{file_id}.enc', 'wb') as fout, open(filename_in, 'rb') as fin:
- fout.write(token_cipher.nonce) # 16 bytes
- fout.write(token_tag) # 16 bytes
- fout.write(auth_secret) # 16 bytes
- fout.write(data_nonce) # 8 bytes
-
- cipher = AES.new(key, AES.MODE_CTR,
- initial_value=struct.pack('<Q', 0), nonce=data_nonce)
-
- block = fin.read(cipher.block_size*chunk_size)
- while block:
- data = cipher.encrypt(block)
- fout.write(data)
- block = fin.read(cipher.block_size*chunk_size)
-
- return file_id, token
-
-def decrypt_generator(file_id, token, seek=0, chunk_size=1000000//16):
- with open(f'{file_id}.enc', 'rb') as fin:
- token_nonce = fin.read(16)
- token_tag = fin.read(16)
- auth_secret = fin.read(16)
- data_nonce = fin.read(8)
-
- ciphertext = base64.b64decode(token)
- token_cipher = AES.new(auth_secret, AES.MODE_GCM, nonce=token_nonce)
- key = token_cipher.decrypt_and_verify(ciphertext, token_tag)
-
- # Use token cipher's block size assuming the two are the same
- cipher = AES.new(key, AES.MODE_CTR,
- initial_value=struct.pack('<Q', seek // token_cipher.block_size), nonce=data_nonce)
- fin.seek(seek - seek % cipher.block_size, 1)
- offset = seek % cipher.block_size
-
- block = fin.read(cipher.block_size*chunk_size)
- while block:
- data = cipher.decrypt(block)
- yield data[offset:]
- offset = 0
- block = fin.read(cipher.block_size*chunk_size)
+from filecrypt import encrypt_file
if __name__ == '__main__':
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('infile')
- parser.add_argument('outfile')
args = parser.parse_args()
+ if not os.path.isfile(args.infile):
+ print(f'{infile} is not a file or directory, exiting.')
+ os.exit(2)
+
file_id, token = encrypt_file(args.infile)
+ print(f'/{file_id}/{token}/{os.path.basename(args.infile)}')
- with open(args.outfile, 'wb', buffering=8192) as fout:
- for data in decrypt_generator(file_id, token):
- fout.write(data)
-
diff --git a/filecrypt.py b/filecrypt.py
new file mode 100644
index 0000000..ce6e3a1
--- /dev/null
+++ b/filecrypt.py
@@ -0,0 +1,71 @@
+import secrets
+from Cryptodome.Cipher import AES
+import base64
+import struct
+import subprocess
+import binascii
+import os
+
+FILE_ID_LENGTH = 22
+TOKEN_LENGTH = 22
+
+def encrypt_file(filename_in, chunk_size=1000000//16):
+ file_id = secrets.token_urlsafe(16)
+ auth_secret = secrets.token_bytes(16)
+ key = secrets.token_bytes(16)
+ data_nonce = secrets.token_bytes(8)
+
+ token_cipher = AES.new(auth_secret, AES.MODE_GCM)
+ ciphertext, token_tag = token_cipher.encrypt_and_digest(key)
+ token = base64.b64encode(ciphertext).rstrip(b'=').decode()
+
+ with open(f'{file_id}.enc', 'wb') as fout, open(filename_in, 'rb') as fin:
+ fout.write(token_cipher.nonce) # 16 bytes
+ fout.write(token_tag) # 16 bytes
+ fout.write(auth_secret) # 16 bytes
+ fout.write(data_nonce) # 8 bytes
+
+ cipher = AES.new(key, AES.MODE_CTR,
+ initial_value=struct.pack('<Q', 0), nonce=data_nonce)
+
+ block = fin.read(cipher.block_size*chunk_size)
+ while block:
+ data = cipher.encrypt(block)
+ fout.write(data)
+ block = fin.read(cipher.block_size*chunk_size)
+
+ return file_id, token
+
+def payload_size(path):
+ return os.stat(path).st_size - 56
+
+def decrypt_generator(filename, token, seek=0, end=None, chunk_size=1000000//16):
+ with open(filename, 'rb') as fin:
+ token_nonce = fin.read(16)
+ token_tag = fin.read(16)
+ auth_secret = fin.read(16)
+ data_nonce = fin.read(8)
+
+ ciphertext = base64.b64decode(token + '='*((3-len(token)%3)%3))
+ token_cipher = AES.new(auth_secret, AES.MODE_GCM, nonce=token_nonce)
+ key = token_cipher.decrypt_and_verify(ciphertext, token_tag)
+
+ # Use token cipher's block size assuming the two are the same
+ cipher = AES.new(key, AES.MODE_CTR,
+ initial_value=struct.pack('>Q', seek // token_cipher.block_size), nonce=data_nonce)
+ print('Seeking to position', seek, 'iv', seek // token_cipher.block_size, 'pos', seek - seek %
+ cipher.block_size, 'offset', seek % cipher.block_size)
+ fin.seek(seek - seek % cipher.block_size, 1)
+ offset = seek % cipher.block_size
+
+ to_send = end - seek + 1 if end else None
+ block = fin.read(cipher.block_size*chunk_size)
+ while block and (to_send is None or to_send > 0):
+ data = cipher.decrypt(block)
+ out = data[offset:to_send]
+ yield out
+ if to_send is not None:
+ to_send -= len(out)
+ offset = 0
+ block = fin.read(cipher.block_size*chunk_size)
+
diff --git a/server.py b/server.py
new file mode 100644
index 0000000..9df3546
--- /dev/null
+++ b/server.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python3
+
+import re
+import os
+
+from flask import Flask, abort, request, Response
+
+import filecrypt
+
+app = Flask(__name__)
+BASE64_RE = re.compile('^[A-Za-z0-9+-_]+=*$')
+
+@app.route('/<file_id>/<token>/<filename>')
+def download(file_id, token, filename):
+ if not BASE64_RE.match(file_id) or len(file_id) != filecrypt.FILE_ID_LENGTH:
+ abort(400, 'Invalid file ID format')
+ if not BASE64_RE.match(token) or len(token) != filecrypt.TOKEN_LENGTH:
+ abort(400, 'Invalid token format')
+
+ path = f'{file_id}.enc'
+ size = filecrypt.payload_size(path)
+
+ range_header = re.match('^bytes=([0-9]+)-([0-9]*)$', request.headers.get('Range', ''))
+ if not range_header:
+ response = Response(
+ filecrypt.decrypt_generator(path, token),
+ mimetype='application/octet-stream')
+ response.headers['Content-Length'] = size
+ else:
+ range_start, range_end = range_header.groups()
+ range_start = int(range_start)
+ range_end = int(range_end) if range_end else size-1
+ if range_start < 0 or range_end >= size or range_start >= range_end:
+ abort(416)
+
+ response = Response(
+ filecrypt.decrypt_generator(path, token, seek=range_start, end=range_end),
+ status = 206,
+ mimetype='application/octet-stream')
+ response.headers['Content-Range'] = f'bytes {range_start}-{range_end}/{size}'
+ response.headers['Content-Length'] = range_end - range_start + 1
+
+ response.headers['Accept-Ranges'] = 'bytes'
+ response.headers['Content-Disposition'] = f'attachment {filename}'
+ return response
+