go get lukechampine.com/jsteg
jsteg is a package for hiding data inside jpeg files, a technique known as
steganography. This is accomplished
by copying each bit of the data into the least-significant bits of the image.
The amount of data that can be hidden depends on the filesize of the jpeg; it
takes about 10-14 bytes of jpeg to store each byte of the hidden data.
// open an existing jpeg
f, _ := os.Open(filename)
img, _ := jpeg.Decode(f)
// add hidden data to it
out, _ := os.Create(outfilename)
data := []byte("my secret data")
jsteg.Hide(out, img, data, nil)
// read hidden data:
hidden, _ := jsteg.Reveal(out)
Note that the data is not demarcated in any way; the caller is responsible for
determining which bytes of hidden it cares about. The easiest way to do this
is to prepend the data with its length.
A jsteg command is included, providing a simple wrapper around the
functions of this package. It can hide and reveal data in jpeg files and
supports input/output redirection. It automatically handles length prefixes
and uses a magic header to identify jpegs that were produced by jsteg.
A more narrowly-focused command named slink is also included. slink embeds
a public key in a jpeg, and makes it easy to sign data and verify signatures
using keypairs derived from password strings. See cmd/slink for a
full description.
Binaries for both commands can be found here.
This package reuses a significant amount of code from the image/jpeg package.
The BSD-style license that governs the use of that code can be found in the
go_LICENSE file.