Question: Assume that we have a stego ECG signal with 200 samples in which binary bits of a text message is hidden as secret message. There are 168 bits of the binary secret message. A bit is hidden in the least significant bit (LSB) of an ECG sample. Please note that the bits are embedded sequentially. For example, we have a text message "hello world". The equivalent binary of secret message is: 011010000110010101101100011011000110111100100000011101110110111 1011100100110110001100100 Now, if we hide first 5 bits of the binary string given above in LSB of first 5 ECG samples then the resultant ECG samples will look like as follows:
ECG Samples
Equivalent Binary Binary After Hiding a bit in LSB
-0.045 10111101001110000101000111101100 10111101001110000101000111101100 -0.055 10111101011000010100011110101110 10111101011000010100011110101111 -0.055 10111101011000010100011110101110 10111101011000010100011110101111 -0.075 10111101100110011001100110011010 10111101100110011001100110011010 -0.065 10111101100001010001111010111000 10111101100001010001111010111001 ? ? ?
You need to perform steganalysis to find out the secret text message from the stego ECG signal. In order to do this, convert each ECG samples into 64 bit binary and read corresponding LSB to store. At the end, convert retrieved bits into text.