A new algorithm for encrypting H.264 SVC (Scalable Video Codec) video data is developed. Security requirements of encoded video are examined together with constraints arising from structural properties of the SVC software. Performance analysis of the new algorithm is reported and its strength against cryptanalysis attacks is discussed. It has been demonstrated that the new algorithm has almost no overhead with low level encryption and acceptable overhead for high level encryption that leads to totally unperceivable video. (C) 2011 Elsevier Inc. All rights reserved.