When we encrypt data we are basically taking the plaintext information and applying some key material or keystream and conducting something called an XOR or Exclusive-OR operation.
The symbol used for XOR is the following: This is a type of cipher known as a stream cipher.
The operation looks like this:
0101 0001 Plain text
0111 0011 Key stream
0010 0010 Output (ciphertext)
As you can see, it's not simple addition and the XOR Operation uses something called a truth table that explains why 0+1=1 and 1+1=0.
The rules are simples, if both bits are the same the result is zero, if both bits are not the same the result is one.
The following answers are incorrect:
- Bit Swapping: Incorrect. This isn't a known cryptographic operations.
- Logical NOR: Sorry, this isn't correct but is where only 0+0=1. All other combinations of 1+1,
1+0 equals 0. More on NOR here.
- Decryption: Sorry, this is the opposite of the process of encryption or, the process of applying the keystream to the plaintext to get the resulting encrypted text.