In this section, we will protect our TCP tunnel with AES encryption. Now, generally speaking, AES encryption can operate in two modes, the Counter (CTR) mode encryption (also called the Stream Mode) and the Cipher Block Chaining (CBC) mode encryption(also called the Block Mode).
The Block Mode means that we need to send data in the form of chunks:
For instance, if we say that we have a block size of 512 bytes and we want to send 500 bytes, then we need to add 12 bytes additional padding to reach 512 bytes of total size. If we want to send 514 bytes, then the first 512 bytes will be sent in a chunk and the second chunk or the next chunk will have a size of 2 bytes. However, we cannot just send 2 bytes alone, as we need to add additional padding of 510 bytes to reach 512 in total for the second chunk. Now, on the receiver side, you would need to reverse the steps by removing the padding and decrypting the...