|Embed secret data in a cover file thereby creating a stego file.|
|Extract secret data from a stego file.|
|Display information about a cover or stego file.|
|Display a list of encryption algorithms and modes that can be used. No arguments required.|
|Display short version information. No arguments required.|
|Display steghides license. No arguments required.|
Display a help screen. No arguments required.
You should use the embed command if you want to embed secret data in a cover file. The following arguments can be used with the embed command:
-ef, --embedfile filename Specify the file that will be embedded (the file that contains the secret message). Note that steghide embeds the original file name in the stego file. When extracting data (see below) the default behaviour is to save the embedded file into the current directory under its original name. If this argument is omitted or filename is -, steghide will read the secret data from standard input.
-cf, --coverfile filename Specify the cover file that will be used to embed data. The cover file must be in one of the following formats: AU, BMP, JPEG or WAV. The file-format will be detected automatically based on header information (the extension is not relevant). If this argument is omitted or filename is -, steghide will read the cover file from standard input.
-sf, --stegofile filename Specify the name for the stego file that will be created. If this argument is omitted when calling steghide with the embed command, then the modifications to embed the secret data will be made directly to the cover file without saving it under a new name.
-e, --encryption algo [ mode ] | mode [ algo ] Specify encryption parameters. This option must be followed by one or two strings that identify an encryption algorithm and/or mode. You can get the names of all available algorithms and supported modes with the encinfo command. The default encryption is rijndael-128 (AES) in the cbc mode. If you do not want to use any encryption, use -e none.
-z, --compress level Specify the compression level. The compression level can be any number in 1...9 where 1 means best speed and 9 means best compression.
-Z, --dontcompress Do not compress the secret data before embedding it.
-K, --nochecksum Do not embed a CRC32 checksum. You can use this if the secret data already contains some type of checksum or if you do not want to embed those extra 32 bits needed for the checksum.
-N, --dontembedname Do not embed the file name of the secret file. If this option is used, the extractor needs to specify a filename to tell steghide where to write the embedded data.
If you have received a file that contains a message that has been embedded with steghide, use the extract command to extract it. The following arguments can be used with this command.
-sf, --stegofile filename Specify the stego file (the file that contains embedded data). If this argument is omitted or filename is -, steghide will read a stego file from standard input.
-xf, --extractfile filename Create a file with the name filename and write the data that is embedded in the stego file to it. This option overrides the filename that is embedded int the stego file. If this argument is omitted, the embedded data will be saved to the current directory under its original name.
You can use the info command to get some information about a cover or stego file (for example the capacity). You might want to use this if you have received a file and you are not sure if it contains an embedded message or if you consider using a certain file as cover file and want to find out its capacity.
The command line steghide info <filename> will print information about <filename> and then ask you if you would like to get information about data that is embedded in that file. If you answer with yes you have to supply the passphrase that was used to embed the data in that file.
You can also supply the -p, --passphrase argument (see below) to the info command which has the effect that steghide will automatically try to get information about the data that has been embedded using the given passphrase.
The following options can be used with all commands (where it makes sense).
-p, --passphrase Use the string following this argument as the passphrase. If your passphrase contains whitespace, you have to enclose it in quotes, for example: -p "a very long passphrase".
-v, --verbose Display detailed information about the status of the embedding or extracting process.
-q, --quiet Supress information messages.
-f, --force Always overwrite existing files.
All file name arguments (-cf, -ef, -sf, -xf) also accept - as a filename which makes steghide use standard input or standard output (whichever makes sense). Omitting the corresponding file name argument will have the same effect as using - with two exceptions: If -sf is omitted for the embed command, then the modifications will be done directly in the cover file. If -xf is omitted for extraction, then the embedded data will be saved under the file name that is embedded in the stego file. So when you want to be sure that standard input/output is used, use - as filename.
The basic usage is as follows:
$ steghide embed -cf picture.jpg -ef secret.txt
embedding "secret.txt" in "picture.jpg"... done
This command will embed the file secret.txt in the cover file picture.jpg.
After you have embedded your secret data as shown above you can send the file picture.jpg to the person who should receive the secret message. The receiver has to use steghide in the following way:
$ steghide extract -sf picture.jpg
wrote extracted data to "secret.txt".
If the supplied passphrase is correct, the contents of the original file secret.txt will be extracted from the stego file picture.jpg and saved in the current directory.
If you have received a file that contains embedded data and you want to get some information about it before extracting it, use the info command:
$ steghide info received_file.wav
format: wave audio, PCM encoding
capacity: 3.5 KB
Try to get information about embedded data ? (y/n) y
embedded file "secret.txt":
size: 1.6 KB
encrypted: rijndael-128, cbc
After printing some general information about the stego file (format, capacity) you will be asked if steghide should try to get information about the embedded data. If you answer with yes you have to supply a passphrase. Steghide will then try to extract the embedded data with that passphrase and - if it succeeds - print some information about it.
Steghide returns 0 on success and 1 if a failure occured and it had to terminate before completion of the requested operation. Warnings do not have an effect on the return value.
Stefan Hetzl <email@example.com>
|-->||STEGHIDE (1)||13 Oct 2003|