81 lines
3.2 KiB
Markdown
81 lines
3.2 KiB
Markdown
# png_data -- Data as images
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## png_data -- Data to PNG
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`png_data` encodes a file into a png image.
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### Encoding
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`png_data -l rgb8 -e file.pdf -o output.png -c "(.pdf) documentation"`
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Where:
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* `rgb8` is the RGB layout with 8 bits per pixel
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* `file.pdf` is the file to store in the resulting image
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* `output.png` the resulting png image
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**Available layouts**
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* `rgb[8|16]` RGB with 8 or 16 bits per channel
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* `rgba[8|16]` RGBA with 8 or 16 bits per channel (densest layout)
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* `g[1|2|4|8|16]` Grayscale with 1-16 bits per channel
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* `ga[1|2|4|8|16]` Grayscale Alpha with 1-16 bits per channel
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### Decoding
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`png_data -d output.png -o original.pdf`
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Where:
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* `output.png` the encoded png image
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* `original.pdf` the resulting decoded file
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### Getting header information
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`png_data -z output.png`
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* `output.png` a `png_data` encoded image
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This will display the header of the encoded file, as well as the comment.
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## png_embed -- Embed files into mostly innocent PNG
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`png_embed` encodes a file into an existing png image making it possible to recover that file by passing the image around.
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### Current algorithm:
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* `lo` Embeds data in the colors channels lowest bits.
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See [examples/test.sh](examples/test.sh) for usage.
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### Encoding an image
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`png_embed -l lo2 -e embed.tar original.png -o output.png -c "(.tar) archive"`
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Where:
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* `lo2` is the `Lo` algorithm using the 2 lowest bits
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* `embed.tar` the file to embed into the final image
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* `original.png` the original PNG file
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* `output.png` the resulting PNG file
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* `"(.tar) archive"` an optional comment
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**Additional Options**
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* `-s|--seed TXT` Sets the random seed for determining the payload blocks. By default the random seed is "WIDTHxHEIGHT" where WIDTH and HEIGHT are the original image's dimensions.
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* `-n|--entropy` Fills unused payload blocks with random data that tries to match the payload's entropy. This feature is experimental and may not fully protect against entropy based steganography-detection. We highlihy recommend that the payload has maximal entropy, which can be achieved by compressing it.
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### Decoding an image
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`png_embed -l lo2 -d image.png -o embed.tar`
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Where:
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* `lo2` is the `Lo` algorithm using the 2 lowest bits
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* `image.png` the PNG containing an embed
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* `embed.tar` the extracted embedded file
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**Additional Options**
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* `-s|--seed TXT` Sets the random seed for determining the payload blocks. By default the random seed is "WIDTHxHEIGHT" where WIDTH and HEIGHT are the original image's dimensions.
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### Getting header information
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`png_embed -l lo2 -z output.png`
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* `lo2` is the `Lo` algorithm using the 2 lowest bits
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* `output.png` a `png_embed` encoded image
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This will display the header of the encoded file, as well as the comment.
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**Additional Options**
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* `-s|--seed TXT` Sets the random seed for determining the payload blocks. By default the random seed is "WIDTHxHEIGHT" where WIDTH and HEIGHT are the original image's dimensions.
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# License
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png_data is licensed under the GNU AGPL version 3 or later. See [LICENSE.md](LICENSE.md) for more information.
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License for third-party dependencies can be accessed via `cargo license`
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