A copy protection (CP) key used by a sending source, such as a POD, to encrypt content such as audio and/or video information is derived by a first key generator associated with a first processor and is locally encrypted by the first processor using a locally generated bus encryption key to produce a bus encrypted CP key that is sent over a local unsecure bus to a second processor, such as a graphics processor. The second processor decrypts the bus encrypted copy key using a decryption engine to obtain the CP key. The second processor receives the encrypted content and in one embodiment, also uses the same decryption engine to decrypt the encrypted content. The first and second processors locally exchange public keys to each locally derive a bus encryption key used to encrypt the CP key before it is sent over the unsecure bus and decrypt the encrypted CP key after it is sent over the bus. The locally exchanged public keys are shorter in length than those used between the CPU and POD to produce the original CP key.