steganography in java

[gaya3]

Hi All,
I'm trying to encrypt the message in the gif image.
is there any algorithm for that to do?
I'm able to get create new image ,and even i retrieved the byte[] of the image.
I want to know how to add the "message" in that byte[].
As we know that messages needed to added at LSB inorder to retaining the
original image.I dont know how to add at LSB.

When i was surfing thro google i came across the contents at

http://www.dreamincode.net/forums/showtopic27950.htm

In that i couldnt get "Bit_Conversion " and "Encode_tex t" part..
can anyone pl help me ASAP..
Thanks in Advance

-Thanks & Regards,
Hamsa

[sukatoa]

Hi All,
I'm trying to encrypt the message in the gif image.
is there any algorithm for that to do?
I'm able to get create new image ,and even i retrieved the byte[] of the image.
I want to know how to add the "message" in that byte[].
As we know that messages needed to added at LSB inorder to retaining the
original image.I dont know how to add at LSB.

When i was surfing thro google i came across the contents at

http://www.dreamincode.net/forums/showtopic27950.htm

In that i couldnt get "Bit_Conversion " and "Encode_tex t" part..
can anyone pl help me ASAP..
Thanks in Advance

-Thanks & Regards,
Hamsa

Maybe this
could help you....

Sukatoa...

[gaya3]

Maybe this
could help you....

Sukatoa...

Thank u Sukatoa... As i'm very much new to this.. I need some basement for that LSB Conversion.. Could u pl help me out?

-Thanks & regards,
Hamsa

[JosAH]

Thank u Sukatoa... As i'm very much new to this.. I need some basement for that LSB Conversion.. Could u pl help me out?

-Thanks & regards,
Hamsa

For those bit operations: let xxxxxxxx be the eight bits in a byte. Let b be a single
bit, either 1 or 0. The following code snippet changes the lowest bit of xxxxxxxx
to b; Here goes:

[code=java]
byte xxxxxxxx= ...; // some byte value
byte b= ...; // either 0 or 1
byte xxxxxxxx= (byte)((xxxxxxx x&0xfe)|b);
[/code]

The value 0xfe in binary is 11111110; if you 'and' another byte value with this you
effectively set the lowest bit to zero. 'or'ing it with 'b' afterwards sets the lowest
bit to 'b'.

kind regards,

Jos

[sukatoa]

Thank u Sukatoa... As i'm very much new to this.. I need some basement for that LSB Conversion.. Could u pl help me out?

-Thanks & regards,
Hamsa

Truth table about AND

a and b = fout

0 0 0
0 1 0
1 0 0
1 1 1


Truth table about OR

a or b = fout

0 0 0
0 1 1
1 0 1
1 1 1

in a register, there are 2 bytes...
since you are focusing in lower significant bit....

at lower byte or higher, there are 8 binary numbers either 0 or 1

first 4 bits (binary digits) are the HSB and the second 4 bit is the LSB

ex. 0000 0000

Applying the AND and OR conversion

AND
0000 0000
1111 1111
---------------------
0000 0000

OR
0000 0000
1111 1111
---------------------
1111 1111

I have not yet experience that kind of implementation in java... I only use it in Assembly...

I hope you could get some idea here...

Apply jo's reply....

[gaya3]

For those bit operations: let xxxxxxxx be the eight bits in a byte. Let b be a single
bit, either 1 or 0. The following code snippet changes the lowest bit of xxxxxxxx
to b; Here goes:

[code=java]
byte xxxxxxxx= ...; // some byte value
byte b= ...; // either 0 or 1
byte xxxxxxxx= (byte)((xxxxxxx x&0xfe)|b);
[/code]

The value 0xfe in binary is 11111110; if you 'and' another byte value with this you
effectively set the lowest bit to zero. 'or'ing it with 'b' afterwards sets the lowest
bit to 'b'.

kind regards,

Jos

Thank u Jos.. Thanks a lot..
Your explanation left me no point for further clarification in LSB conversion..
I need one small clarifiaction for "bit conversion" in this link..
http://www.dreamincode .net/forums/showtopic27950. htm
what they are trying to do there? I couldnt get that..pl help me out..

-Thanks & Regards,
Hamsa

[JosAH]

You mean this method? (ripped from that link):

[code=java]
private byte[] bit_conversion( int i)
{
byte byte3 = (byte)((i & 0xFF000000) >>> 24);
byte byte2 = (byte)((i & 0x00FF0000) >>> 16);
byte byte1 = (byte)((i & 0x0000FF00) >>> 8 );
byte byte0 = (byte)((i & 0x000000FF) );
return(new byte[]{byte3,byte2,by te1,byte0});
}
[/code]

That int i value represents a color 'ARGB' which is a four byte value in one int:
the alpha factor and the red, green and blue component values. The method
just pulls the four bytes out of that in and returns a four element byte array.

It gets those bytes (eight bits) by masking all the irrelevant bits away and shifting
the values to the lowest possible position.

kind regards,

Jos

[gaya3]

You mean this method? (ripped from that link):

[code=java]
private byte[] bit_conversion( int i)
{
byte byte3 = (byte)((i & 0xFF000000) >>> 24);
byte byte2 = (byte)((i & 0x00FF0000) >>> 16);
byte byte1 = (byte)((i & 0x0000FF00) >>> 8 );
byte byte0 = (byte)((i & 0x000000FF) );
return(new byte[]{byte3,byte2,by te1,byte0});
}
[/code]

That int i value represents a color 'ARGB' which is a four byte value in one int:
the alpha factor and the red, green and blue component values. The method
just pulls the four bytes out of that in and returns a four element byte array.

It gets those bytes (eight bits) by masking all the irrelevant bits away and shifting
the values to the lowest possible position.

kind regards,

Jos

Jos i have got new concept from you.. Does "i" is not something like message length? which means the message v need to encrypt.then where does 'ARGB' comes to picture?sorry for inconvenience .if you dont mind, can u please explain me with example?

-Thanks & Regards,
Hamsa

[waikit0513]

Hi ,

i am also doing Steganography project to hide msg in GIF.
Could I know, Is it need to decompress the gif and chnage the bit then compress it to become the Stegoed Image?

I am facing the problem on the loading of GIF file into the int[].
anyone know how was the GIF structure work ?


Regards
Kit

[BigDaddyLH]

Hi ,

i am also doing Steganography project to hide msg in GIF.
Could I know, Is it need to decompress the gif and chnage the bit then compress it to become the Stegoed Image?

I am facing the problem on the loading of GIF file into the int[].
anyone know how was the GIF structure work ?


Regards
Kit

It's simpler to ignore the image's file format. Read in the image:

[CODE=Java]BufferedImage image = ImageIO.read(in File);[/CODE]

Tweak pixel bits then write it out:

[CODE=Java]ImageIO.write(i mage, "gif", outFile);[/CODE]

Here is an example I wrote awhile back, under a different username:

http://forum.java.sun.com/thread.jspa?threadID=5157446&messageID=10074389&start=2

The message embedded is the program for embedding the message!

[gaya3]

It's simpler to ignore the image's file format. Read in the image:

[CODE=Java]BufferedImage image = ImageIO.read(in File);[/CODE]

Tweak pixel bits then write it out:

[CODE=Java]ImageIO.write(i mage, "gif", outFile);[/CODE]

Here is an example I wrote awhile back, under a different username:

http://forum.java.sun.com/thread.jspa?threadID=5157446&messageID=10074389&start=2

The message embedded is the program for embedding the message!

Hi,
Thank u.. Example u have shown is quite good..
i like to know what for this following block needed in that example?

static byte[] convert(int x) {
int b3 = (x & 0xff000000) >>> 24;
int b2 = (x & 0xff0000) >>> 16;
int b1 = (x & 0xff00) >>> 8;
int b0 = x & 0xff;
return new byte[]{(byte)b3, (byte)b2, (byte)b1, (byte)b0};
}
what they are trying to do in the above code?

-Thanks & Regards,
Hamsa

[JosAH]

Hi,
Thank u.. Example u have shown is quite good..
i like to know what for this following block needed in that example?

static byte[] convert(int x) {
int b3 = (x & 0xff000000) >>> 24;
int b2 = (x & 0xff0000) >>> 16;
int b1 = (x & 0xff00) >>> 8;
int b0 = x & 0xff;
return new byte[]{(byte)b3, (byte)b2, (byte)b1, (byte)b0};
}
what they are trying to do in the above code?

-Thanks & Regards,
Hamsa

That's the same thing you were asking about to me. Suppose a four byte number:
aarrggbb, where the a's, r's, g's and b's are hexadecimal digits.

aarrgbb &0xff000000 == aa000000
aa000000 >>> 24 == aa

aarrggbb &0xff0000 == rr0000
rr0000 >>> 16 == rr

etc. etc.

That little method takes apart the four bytes in an int and stores the bytes in a
byte array.

kind regards,

Jos

[BigDaddyLH]

That's the same thing you were asking about to me. Suppose a four byte number:
aarrggbb, where the a's, r's, g's and b's are hexadecimal digits.

aarrgbb &0xff000000 == aa000000
aa000000 >>> 24 == aa

aarrggbb &0xff0000 == rr0000
rr0000 >>> 16 == rr

etc. etc.

That little method takes apart the four bytes in an int and stores the bytes in a
byte array.

kind regards,

Jos

Indeed. You should be able to guess the intent of the method from its signature alone!