A Python MP4 decrypter for CENC encrypted MP4s
pymp4decrypt uses the excellent parsing library by beardypig, but with some extra modifications for CENC boxes.
By itself as a script:
python decrypt.py -k KEY -i INPUT_FILE_ENCRYPTED.mp4 -o OUTPUT_FILE_DECRYPTED.mp4
As a library:
>>> import binascii
>>> import pymp4decrypt
>>> enc = open('encrypted.mp4', 'rb')
>>> dec = open('decrypted.mp4', 'wb')
>>> key = binascii.unhexlify('4ce68c303ae037a59888d4866de39ffb')
>>> pymp4decrypt.decrypt(key, enc, dec)
>>>