pywks/init_pssh.py

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2023-11-16 08:08:47 +00:00
import base64
import sys
from pathlib import Path
from google.protobuf.message import DecodeError
from cdm.wks import WidevineCencHeader
# File path to read the raw data
file_path = "your init"
# Read the raw data from the file
raw = Path(file_path).read_bytes()
# Find the offset of 'pssh' in the raw data
pssh_offset = raw.rfind(b'pssh')
if pssh_offset == -1:
print("[ERROR] 'pssh' not found in the file.")
sys.exit(1)
else:
# Extract the PSSH data based on the offset and length information
_start = max(pssh_offset - 4, 0)
_end = min(pssh_offset - 4 + raw[pssh_offset - 1], len(raw))
pssh = raw[_start:_end]
# Display the PSSH data in base64 format
print('\n[INFO] PSSH:', base64.b64encode(pssh).decode('utf-8'))
pssh_b64 = base64.b64encode(pssh)
print("\n[SUCCESS] PSSH extracted successfully.")
# Check if the PSSH data needs modification
if not pssh[12:28] == bytes([237, 239, 139, 169, 121, 214, 74, 206, 163, 200, 39, 220, 213, 29, 33, 237]):
print("[Modifying PSSH data...]")
# Create a new PSSH data with the required modifications
new_pssh = bytearray([0, 0, 0])
new_pssh.append(32 + len(pssh))
new_pssh[4:] = bytearray(b'pssh')
new_pssh[8:] = [0, 0, 0, 0]
new_pssh[13:] = [237, 239, 139, 169, 121, 214, 74, 206, 163, 200, 39, 220, 213, 29, 33, 237]
new_pssh[29:] = [0, 0, 0, 0]
new_pssh[31] = len(pssh)
new_pssh[32:] = pssh
pssh_b64 = base64.b64encode(new_pssh)
print("[Modified PSSH data:", pssh_b64.decode(), "]")
else:
print("[PSSH data doesn't need modification.]")
# Parse the modified or original PSSH data using WidevineCencHeader
parsed_init_data = WidevineCencHeader()
try:
parsed_init_data.ParseFromString(base64.b64decode(pssh_b64))
print("[PSSH data parsed successfully.]")
except (DecodeError, SystemError) as e:
print("[Error parsing PSSH data:", e, "]")
try:
# Attempt to parse PSSH data from byte offset 32
id_bytes = parsed_init_data.ParseFromString(base64.b64decode(pssh_b64)[32:])
print("[PSSH data parsed successfully from byte offset 32.]")
except DecodeError as de:
print("[Error parsing PSSH data from byte offset 32:", de, "]")
sys.exit(1)
# Convert the parsed key_id to a hexadecimal string
key_id_str = ''.join(['{:02x}'.format(b) for b in parsed_init_data.key_id[0]])
print("[Key ID in hexadecimal:", key_id_str, "]")
print("\n[SUCCESS] [Done]\n")