Methods for optical image encryption and decryption based on biological information

A method for encrypting and decrypting biological information based on a biological image, comprising:

• acquiring biological information that comprises fingerprint, iris, face, palm print, and voiceprint;
• preprocessing the biological information using a chaotic mapping method to construct a first chaotic biological phase plate and a second chaotic biological phase plate;
• acquiring an original image to be encrypted, and performing discrete cosine transform on the original image to be encrypted, to obtain an encrypted image after discrete cosine transform;
• multiplying the first chaotic biological phase plate with the encrypted image after discrete cosine transform to obtain an encrypted image modulated by the first chaotic biological phase plate;
• performing a first Fresnel transformation on the encrypted image modulated by the first chaotic biological phase plate to obtain an encrypted image after the first Fresnel transformation;
• performing a first phase truncation and phase preservation on the encrypted image after the first Fresnel transform to obtain an encrypted image after the first phase truncation and phase preservation;
• multiplying the second chaotic biological phase plate with the encrypted image after the first phase truncation and phase preservation to obtain an encrypted image modulated by the second chaotic biological phase plate;
• performing a second Fresnel transform on the encrypted image modulated by the second chaotic biological phase plate to obtain an encrypted image after the second Fresnel transform;
• performing a second phase truncation and phase preservation on the encrypted image after the second Fresnel transform to obtain an encrypted image after the second phase truncation and phase preservation;
• causing the encrypted image after the second phase truncation and phase preservation to undergo Fresnel diffraction, and an interference with an introduced reference light to output a light intensity distribution of a plane hologram as a final encrypted image;
• and;
• obtaining users' biological information;
• judging whether the user is a legal user according to the biological information of the user;
• if so, acquiring a first key and a second key, and irradiating the final encrypted image with reference light;
• decrypting the final encrypted image after irradiation according to the first key and the second key;
• by using a Fresnel inverse transform method and the chaotic mapping method to obtain the original image;
• if not, stopping decryption.