func read_stego(img io.Reader, secret string, out io.Writer) {
// see if encryption is used or not
var encrypt bool = false
var crypt *rc4.Cipher
if secret != "" {
encrypt = true
var err error
crypt, err = rc4.NewCipher([]byte(secret))
if err != nil {
panic(err)
}
// when the function is finished, zero the keyspace
defer crypt.Reset()
}
// get a buffer to read data from the image
buf := make([]byte, 128)
// create the stego img reader to read the data
stegoReader, err := stegoimg.NewStegoImgReader(img)
if err != nil {
panic(err)
}
// read and decrypt the data
for {
// read the new data block
n, err := stegoReader.Read(buf)
if err != nil && err != io.EOF {
panic(err)
}
// break if no data was read
if n == 0 {
break
}
// optionally decrypt
if encrypt {
crypt.XORKeyStream(buf[:n], buf[:n])
}
// write to the stego writer
_, writeErr := out.Write(buf[:n])
if writeErr != nil {
panic(writeErr)
}
// break if that's the end of the data
if err == io.EOF {
break
}
}
return
}
func write_stego(img, data io.Reader, secret string, out io.Writer) {
// see if encryption is used or not
var encrypt bool = false
var crypt *rc4.Cipher
if secret != "" {
encrypt = true
var err error
crypt, err = rc4.NewCipher([]byte(secret))
if err != nil {
panic(err)
}
// when the function is finished, zero the keyspace
defer crypt.Reset()
}
// get a buffer to read data from the data
buf := make([]byte, 128)
// create the new stego img writer to encode the data
stegoWriter, err := stegoimg.NewStegoImgWriter(img, out)
if err != nil {
panic(err)
}
defer stegoWriter.Close()
// read and encode the data
for {
// read the new data block
n, err := data.Read(buf)
if err != nil && err != io.EOF {
panic(err)
}
// break if no data was read
if n == 0 {
break
}
// optionally encrypt
if encrypt {
crypt.XORKeyStream(buf[:n], buf[:n])
}
// write to the stego writer
_, writeErr := stegoWriter.Write(buf[:n])
// check if the image filled up
if writeErr == stegoimg.ImageFullError && err != io.EOF {
fmt.Println("Image full before data finished")
break
}
// break if that's the end of the data
if err == io.EOF {
break
}
}
// finished creating the image
return
}
