**Abstract**

Fragile watermarking algorithm is a technique used to authenticate of digital data multimedia such as video. A watermarking algorithm consists of two processes: embedding and extraction of watermark. In this paper, a secure video fragile watermarking algorithm in spatial domain based on chaos is proposed. The watermark is a binary image which has the same size with frame size of the video. Before embedding, in order to increase security, the watermark is encrypted using XOR operation with a random image. The random image is generated by using Cross-Coupled Chaotic random Bit Generator (CCCBG). The encrypted watermark is embedded to each frame. In the extraction process, the encrypted watermark is extracted from the watermarked video, decrypted it, and then compared to the original watermark. This algorithm has capability to localize the area being tampered in the video frames. We have performed some typical attacks to the watermarked video and then authenticated it. Based on the experiment results, the algorithm can detect and localize the modified region of video frames very well. Sensitivity to the slightest change on initial conditions of the chaos map provided security of the algorithm.

**Keywords:** fragile watermarking, authentication, digital video, chaos
