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Fix CBC mode padding and use adler32 for checksums (#315)

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* Fix CBC mode padding and use adler32 for checksums

* Change line order

This change comes to improve the readability of the code.

* Use zero-padding for CBC mode
This commit is contained in:
Daniel Høyer Iversen 2020-03-04 22:24:09 +01:00 • committed by GitHub
parent dfd478922b
commit 8e7446f410
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 9 additions and 26 deletions
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35
broadlink/__init__.py
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@ -8,6 +8,7 @@ import struct
import threading import threading
import time import time
from datetime import datetime from datetime import datetime
from zlib import adler32
from cryptography.hazmat.backends import default_backend from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
@ -109,11 +110,8 @@ def discover(timeout=None, local_ip_address=None):
packet[0x1c] = port & 0xff packet[0x1c] = port & 0xff
packet[0x1d] = port >> 8 packet[0x1d] = port >> 8
packet[0x26] = 6 packet[0x26] = 6
checksum = 0xbeaf
for i in range(len(packet)): checksum = adler32(packet, 0xbeaf) & 0xffff
checksum += packet[i]
checksum = checksum & 0xffff
packet[0x20] = checksum & 0xff packet[0x20] = checksum & 0xff
packet[0x21] = checksum >> 8 packet[0x21] = checksum >> 8
@ -251,26 +249,17 @@ class device:
# pad the payload for AES encryption # pad the payload for AES encryption
if payload: if payload:
numpad = (len(payload) // 16 + 1) * 16 payload += bytearray(((len(payload)-1)//16+1)*16 - len(payload))
payload = payload.ljust(numpad, b"\x00")
checksum = adler32(payload, 0xbeaf) & 0xffff
checksum = 0xbeaf
for i in range(len(payload)):
checksum += payload[i]
checksum = checksum & 0xffff
payload = self.encrypt(payload)
packet[0x34] = checksum & 0xff packet[0x34] = checksum & 0xff
packet[0x35] = checksum >> 8 packet[0x35] = checksum >> 8
payload = self.encrypt(payload)
for i in range(len(payload)): for i in range(len(payload)):
packet.append(payload[i]) packet.append(payload[i])
checksum = 0xbeaf checksum = adler32(packet, 0xbeaf) & 0xffff
for i in range(len(packet)):
checksum += packet[i]
checksum = checksum & 0xffff
packet[0x20] = checksum & 0xff packet[0x20] = checksum & 0xff
packet[0x21] = checksum >> 8 packet[0x21] = checksum >> 8
@ -403,9 +392,7 @@ class bg1(device):
for i in range(len(js)): for i in range(len(js)):
packet.append(js[i]) packet.append(js[i])
checksum = 0xc0ad checksum = adler32(packet[0x08:], 0xc0ad) & 0xffff
for c in packet[0x08:]:
checksum = (checksum + c) & 0xffff
packet[0x06] = checksum & 0xff packet[0x06] = checksum & 0xff
packet[0x07] = checksum >> 8 packet[0x07] = checksum >> 8
@ -969,11 +956,7 @@ def setup(ssid, password, security_mode):
payload[0x85] = pass_length # Character length of password payload[0x85] = pass_length # Character length of password
payload[0x86] = security_mode # Type of encryption (00 - none, 01 = WEP, 02 = WPA1, 03 = WPA2, 04 = WPA1/2) payload[0x86] = security_mode # Type of encryption (00 - none, 01 = WEP, 02 = WPA1, 03 = WPA2, 04 = WPA1/2)
checksum = 0xbeaf checksum = adler32(payload, 0xbeaf) & 0xffff
for i in range(len(payload)):
checksum += payload[i]
checksum = checksum & 0xffff
payload[0x20] = checksum & 0xff # Checksum 1 position payload[0x20] = checksum & 0xff # Checksum 1 position
payload[0x21] = checksum >> 8 # Checksum 2 position payload[0x21] = checksum >> 8 # Checksum 2 position