Neil F. Johnson. Steganography. Technical Report. November 1995.

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3.3.1 Hide and Seek v 4.1

Hide and Seek versions 4.1 and 5.0 by Colin Maroney have similar limitations with minimum image sizes (320 x 480). In version 4.1 if the image is smaller than the minimum, then the stego-image is padded with black space. If the cover image is larger, the stego-image is cropped to fit. In version 5.0 the same is true with minimum image sizes. If any image exceeds 1024 x 768, an error message is returned. The Hide and Seek 1.0 for Windows 95 version seems to have these issues resolved and is a much improved steganography tool. Version 4.1 is evaluated here to illustrate limitations of some steganography tools.

Hide and Seek 4.1 is free software which contains a series of DOS programs that embed data in GIF files and comes with the source code.

Hide and Seek uses the Least Significant Bit of each pixel to encode characters, 8 pixels per character and spreads the data throughout the GIF in a somewhat random fashion. The larger the message the more likely the resulting image will be degraded. Since the data is dispersed "randomly" and the message file header is encrypted, there is no telling what is in an embedded file.

Unfortunately the hidden file can be no longer than 19,000 bytes because the maximum display used is 320 x 480 pixels. Each character takes 8 pixels two hide ( (320x480)/8 = 19200).

C2 (Shakespeare) was used to embed M1. The original image of Shakespeare is 222 x 282 pixels and 256 shades of gray. The resulting image was forced to 320 x 480 pixels. Instead of "stretching" the image to fit, large black areas were added to the image making it 320 x 480. The image on the left is the original C2 and the image on the right is embedded with M1.

 [Fig 7: Result of embedding Message1 into Container2 (37k)]

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