An image file has three 8-bit components per pixel. These three components speci

Question

An image file has three 8-bit components per pixel. These three components specify the strength of the red (R), green (G) and blue (B) colours in a pixel. It is thought that the image file hides a message using LSB steganography, where the least-significant bit of each colour component may hide a bit. The message is thought to be ASCll-encoded and null terminated. The RGB values of the first eight pixels of the image are given below (expressed in hexadecimal). 0x7289D2, 0x6C8BCE, 0x6893D2, 0x697FC2, 0x768AC1, 0x688DC4, 0x7986C9, 0x6A81C5 What is likely to be the first ASCII character of the hidden message?

Explanation / Answer

Given hex decimal to binary

0x7289D2 0111 0010 1000 1001 1101 0010 ->  
0x6C8BCE 0110 1100 1000 1011 1100 1110
0x6893D2 0110 1000 1001 0011 1101 0010
0x697FC2 0110 1001 0111 1111 1100 0010
0x768AC1 0111 0110 1000 1010 1100 0001
0x688DC4 0110 1000 1000 1101 1100 0100
0x7986C9 0111 1001 1000 0110 1100 1001
0x6A81C5 0110 1010 1000 0001 1100 0101

first 8 bit for R second 8 bit for G third eight bit for Blue

choose last bit of each color as

0x7289D2 0111 0010 1000 1001 1101 0010 -> 010
0x6C8BCE 0110 1100 1000 1011 1100 1110- > 010
0x6893D2 0110 1000 1001 0011 1101 0010 - > 010
0x697FC2 0110 1001 0111 1111 1100 0010 -> 110
0x768AC1 0111 0110 1000 1010 1100 0001 -> 001
0x688DC4 0110 1000 1000 1101 1100 0100-> 010
0x7986C9 0111 1001 1000 0110 1100 1001-> 101
0x6A81C5 0110 1010 1000 0001 1100 0101- > 011

we get string of 010010010110001010101011

to bits

01001001 01100010 10101011

convert bin to ascii is " Ib« "

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