Extension visual encryption and decryption method

Abstract

The invention discloses an extension visual encryption and decryption method. In the extension visual encryption process, a cover image is chunked first, and pixels in each block are divided into secret information pixels, auxiliary black pixels and common pixels; then (2,2) lines of a visual cryptography fundamental matrix are filled at the position of secret information, share images are divided into four areas, and secret images and watermark images are sequentially embedded into the four areas; at last, limited error diffusion is used for incorporating the characteristics of the cover image. In the extension visual decryption process, the two share images are overlaid in a staggered mode, and watermarks are recovered; then the two images align to each other to recover secret images. The extension visual encryption and decryption method has the advantages that image sharing is meaningful, the dimension is not extended, decryption does not need a computer, a tampering authentication function is achieved, and the recovered secrete images and the watermarks can be free of interference of the cover images at the same time.

Description

technical field [0001] The invention relates to an extended visual encryption method and an extended visual decryption method. Background technique [0002] Visual encryption is a secret sharing method that is efficient in the decoding process and does not require any calculation. It divides a secret image into n parts for transmission. Only when at least k parts are obtained, the content of the secret image can be recovered by superimposing them. However, the shared images generated by general visual encryption methods appear as meaningless noise, which may attract the attention of potential attackers during transmission and arouse the attacker's interest in intercepting or cracking. In addition, the shared image may be intercepted by the attacker during the transmission process, and the attacker may carry out a replacement attack on the intercepted shared image. Image 1 constructs a forged shared image 2, superimposes shared image 1 and forged shared image 2, and recovers...

AI Technical Summary

Problems solved by technology

[0003] To sum up, the existing visual encryption methods have the following defects: (1) the generated shared image is meaningless; (2) the generated shared image has pixel expansion relative to the masked image; (3) when decoding secret information Computer participation is required; (4) there is no tampering authentication function; (5) there is interference from the carrier image on the recovered secret information or watermark

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