In the field of medical image content protection and security sharing, the introduction of blockchain technology has a problem in that the secret key may be lost and cannot be recovered. Therefore, this paper proposes an authenticable medical image-sharing scheme based on an embedded small shadow QR code and a blockchain framework. First, a small shadow image is obtained by employing a secret image-sharing method based on the Chinese remainder theorem. Then, the shadow image is embedded into a

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... R code with error correction. This not only ensures the security and integrity of the shadow image transmission in the public channel but also avoids the problem where the secret key is lost and cannot be recovered. Compared with some existing excellent schemes, our scheme adopts a hash bit stream for authentication purposes and employs smart contracts to authenticate and restore secret images, thus reducing the local load. In addition, experiments validate that the recovered secret medical image is lossless and that the cover QR code is more robust and secure. This method is suitable for medical image content protection and security sharing.