Device, method, and program for image encryption/decryption

An image decryption device that decrypts an encrypted image into a digital image, comprising:

• marker detection means for detecting a specified marker set in the encrypted image in order to locate a position of a partial area that was encrypted;
• encrypted area detection means for detecting an encrypted image area on the basis of the marker detected by the marker detection means;
• encryption position detection means for detecting an encryption position around which pixel values are converted regularly in the encrypted image area detected by the encrypted area detection means;
• and
• decryption means for decrypting the encrypted image area into the digital image on the basis of the encryption position detected by the encryption position detection means and a decryption key.

An image decryption device that decrypts an encrypted image into a digital image, comprising:

• encrypted area detection means for detecting an encrypted image area;
• encryption position detection means for detecting an encryption position around which pixel values are converted regularly in the encrypted image area detected by the encrypted area detection means;
• decryption means for decrypting the encrypted image area into the digital image on the basis of the encryption position detected by the encryption position detection means and a decryption key;
• and
• checking mark detection means for detecting a specified checking mark for verifying appropriateness of decryption on the basis of the digital image obtained by decryption by the decryption means.

An image decryption device that decrypts an encrypted image into a digital image, comprising:

• marker detection means for detecting a specified marker set in the encrypted image in order to locate a position of a partial area that was encrypted;
• encrypted area detection means for detecting an encrypted image area on the basis of the marker detected by the marker detection means;
• encryption position detection means for detecting an encryption position around which pixel values are converted regularly in the encrypted image area detected by the encrypted area detection means;
• decryption means for decrypting the encrypted image area into the digital image on the basis of the encryption position detected by the encryption position detection means and a decryption key;
• and
• checking mark detection means for detecting a specified checking mark for verifying appropriateness of decryption on the basis of the digital image obtained by decryption by the decryption means.

A method of encrypting an image executed in an image encryption device that encrypts a digital image into an encrypted image, comprising:

• specifying a partial area to be encrypted in the digital image;
• converting the selected partial area into a processed image on the basis of an encryption key;
• and
• generating a converted image by regularly converting pixel values of the processed image obtained through the conversion so that a position of the partial area can be located.

A method of decrypting an image executed in an image decryption device that decrypts an encrypted image into a digital image, comprising:

• detecting a specified marker set in the encrypted image in order to locate a position of a partial area that was encrypted;
• detecting an encrypted image area on the basis of the detected marker;
• detecting an encryption position around which pixel values are converted regularly in the detected encrypted image area;
• and
• decrypting the encrypted image area into the digital image on the basis of the detected encryption position and a decryption key.

A method of decrypting an image executed in an image decryption device that decrypts an encrypted image into a digital image, comprising:

• detecting an encrypted image area;
• detecting an encryption position around which pixel values are converted regularly in the detected encrypted image area;
• decrypting the encrypted image area into the digital image on the basis of the detected encryption position and a decryption key;
• and
• detecting a specified checking mark for verifying appropriateness of decryption on the basis of the digital image obtained by decryption.

A method of decrypting an image executed in an image decryption device that decrypts an encrypted image into a digital image, comprising:

• detecting a specified marker set in the encrypted image in order to locate a position of a partial area that was encrypted;
• detecting an encrypted image area on the basis of the detected marker;
• detecting an encryption position around which pixel values are converted regularly in the detected encrypted image area;
• decrypting the encrypted image area into the digital image on the basis of the detected encryption position and a decryption key;
• and
• detecting a specified checking mark for verifying appropriateness of decryption on the basis of the digital image obtained by decryption.

An image encryption program for causing a computer of an image encryption device that encrypts a digital image into an encrypted image to function as:

• encryption area specifying means for specifying a partial area to be encrypted in the digital image;
• image conversion means for converting the partial area selected by the encryption area specifying means into a processed image on the basis of an encryption key;
• and
• pixel value conversion means for generating a converted image by regularly converting pixel values of the processed image obtained through the conversion by the image conversion means so that a position of the partial area can be located.

An image decryption program for causing a computer of an image decryption device that decrypts an encrypted image into a digital image to function as:

• marker detection means for detecting a specified marker set in the encrypted image in order to locate a position of a partial area that was encrypted;
• encrypted area detection means for detecting an encrypted image area on the basis of the marker detected by the marker detection means;
• encryption position detection means for detecting an encryption position around which pixel values are converted regularly in the encrypted image area detected by the encrypted area detection means;
• and
• decryption means for decrypting the encrypted image area into the digital image on the basis of the encryption position detected by the encryption position detection means and a decryption key.

An image decryption program for causing a computer of an image decryption device that decrypts an encrypted image into a digital image to function as:

• encrypted area detection means for detecting an encrypted image area;
• encryption position detection means for detecting an encryption position around which pixel values are converted regularly in the encrypted image area detected by the encrypted area detection means;
• decryption means for decrypting the encrypted image area into the digital image on the basis of the encryption position detected by the encryption position detection means and a decryption key;
• and
• checking mark detection means for detecting a specified checking mark for verifying appropriateness of decryption on the basis of the digital image obtained by decryption by the decryption means.

An image decryption program for causing a computer of an image decryption device that decrypts an encrypted image into a digital image to function as:

• marker detection means for detecting a specified marker set in the encrypted image in order to locate a position of a partial area that was encrypted;
• encrypted area detection means for detecting an encrypted image area on the basis of the marker detected by the marker detection means;
• encryption position detection means for detecting an encryption position around which pixel values are converted regularly in the encrypted image area detected by the encrypted area detection means;
• decryption means for decrypting the encrypted image area into the digital image on the basis of the encryption position detected by the encryption position detection means and a decryption key;
• and
• checking mark detection means for detecting a specified checking mark for verifying appropriateness of decryption on the basis of the digital image obtained by decryption by the decryption means.