A system and method for decrypting encrypted media that have changing initialization vectors and keys is disclosed. As encrypted media is received and played back, the encrypted frames can be monitored (e.g., checked) to detect whether or not initialization vectors are prepended to them. If a prepended initialization vector is detected, the prepended initialization vector is used to facilitate the decryption of the encrypted frame. If no prepended initialization vector is detected, a new initialization vector is generated by using a last portion of bytes of the preceding encrypted frame and the new initialization vector is used to facilitate the decryption of the encrypted frame. A signal byte can be included to signal whether the frame is encrypted or not, whether an initialization vector is included, and other information about the encrypted frame.