By using the leveled characteristics of fine granularity scalable (FGS) compressed video

the MPEG4 video object coding rules and the improved CS(chain and sum)

the base-level encryption algorithm

which is based on Video object plane (VOP) in Fine-grain extensible coding

retrieve and encrypt the key data

including shape

texture

motion and global background

of the base-level VOP to encrypt the FGS steaming.The algorithm supports the transform coding of the network node to adapt to the variation of the bandwidth without any encryption and decryption operations.The use of encryption in VOP unit and CS algorithm effectively reduce the media stream package loss and transport errors.There is no size increment in the encrypted data steam and the variation of the encrypted key withstands the Known-plaintext attack.By the experiments on three series forman

akyio and carphone provided by Moving Pictures Experts Group (MPEG) in a sampling rate of 3 of 300 processing frames

the processing speed of CS

RC4 and RC5 are 23.5

64.5 and 42.7M b/s.The results also show a satisfying encrypted security and descrambled visual effect.