On the Security of Selectively Encrypted HEVC Video Bitstreams

What is it about?

With the increasing use of videos in various applications, ensuring their security has become crucial. Selective encryption (SE) is a widely used method to protect video content because it works well with video codecs, maintains acceptable visual distortion, and is computationally efficient. However, little attention has been given to the security of SE against cryptographic attacks. In our work, we identify vulnerabilities in SE-encrypted video bitstreams and propose two known plaintext attacks (KPAs) to exploit them. We also suggest a defense strategy to counter these attacks. Our analysis demonstrates that existing SE schemes in HEVC videos can be compromised. By leveraging selected syntax elements recorded during video encoding and incorporating them into the decoding process, we can reconstruct critical encryption parameters and design a pseudo-key stream (PKS) to decrypt the protected content. Our experiments show that the proposed KPAs can break two SE schemes, with an average key stream estimation accuracy of over 93% for a single bitstream and up to 99% with multiple bitstreams.

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Photo by Sam McGhee on Unsplash

Photo by Sam McGhee on Unsplash

Why is it important?

Ensuring video security is critical as video content is widely used in various applications, including streaming, surveillance, and communications. Selective encryption (SE) is a popular approach due to its efficiency, but its security against cryptographic attacks has been largely overlooked. If SE schemes are vulnerable, attackers can potentially recover protected video content, leading to privacy breaches, intellectual property theft, or unauthorized access to sensitive information. By analyzing these vulnerabilities and demonstrating successful known plaintext attacks (KPAs), our research highlights the need for stronger security measures in SE schemes to prevent potential exploitation.

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