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Enciphering and Deciphering Images

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Introduction to Enciphering and Deciphering Images

Most images, by design, are made to be viewed often and by many people. Web images, for example, may be viewed hundreds of times a day by a multitude of web vistors. However, in some cases, you may want to keep a particular image private so that only you or perhaps a select group of your friends or web visitors can view it. ImageMagick permits you to scramble your images such that unless someone knows your passphrase, they will be unable to view the original content.

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Encipher an Image

Use the -encipher option to scramble your image so that it is unrecognizable. The option requires a filename that contains your passphrase. In this example we scramble an image and save it in the PNG format:

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$magick> convert rose.jpg -encipher smiley.gif rose.png

Decipher an Image

Use the -decipher option to unscramble your image so that it is recognizable once again. The option requires a filename that contains your passphrase. In this example we unscramble an image and save it in the JPEG format:

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$magick> convert rose.png -decipher passphrase.txt rose.jpg

Encipher and Decipher Caveats

Some formats do not support enciphered pixels-- the JPEG or GIF format, for @@ -236,8 +262,8 @@ use a standard cipher and mode so other vendors are encouraged to support enciphered image content.

Some small practical examples of image enciphering can be found in IM -Examples Encrypting Image Data.

+Examples Encrypting Image Data.

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