HOW YOUR SMS IS ENCRYPTED?

    

   We know, in this digital world, all the information is digitized(represented in binary using 1 s and 0 s). 

     Say, your plain text (SMS) is digitized as,
Plain text:  1100101....
To encrypt the above message we build a key stream as given below.
key stream:  1010110.... 
 Here '1' means "change the corresponding bit (binary digit) in the plain text".  That is, 1 in plain text changes to 0 and vice versa.
'0' means"leave the bit in the corresponding position as it is ".

How it works:
Plain text ; SMS: 1100101.....
Key stream:         1010110....
Encrypted text:    0110011.....

Here first bit in the 'plain text' is converted to '0' because '1' in the first position of key stream.  The second bit '1' in the plain text is left untouched due to '0' in the key stream. It goes on.....

     The encrypted message now can be sent through any open channel.  No body can unwrap and find the original message.  Because one requires key to decrypt it.

How it is decrypted in your mobile?  If you apply the same key stream to the encrypted message, it will revert back to the original message.  Because, in binary language there are only 2 digits (0,1).  Hence the second time conversion using the same key will naturally bring back the original text.
    The secrecy of 'key stream' must be maintained .  The key can be generated at the sender's end or at the receiver's end based on some rules like

1. Repeat 1101 pattern like
     1101 1101 1101........ 
2. Repeat 1010 pattern, but change the last 2 bits every time.
example:  1010 1001 1010 1001.....
Anyway, keystream should not be predictable or breakable.

Your SMS, chat, talk are strongly encrypted and they are safe.