encryption - When encrypting data that is not an even multiple of the block size do I have to send a complete last block? -

If I am using a block cipher such as AES that has a block size of 128 bits, what should I do if My data is not too many of 128 bit? I'm working with data packets and do not want to change the size of my packet when encrypting, even though my data is not too many of 128?

Does the AES block cipher allow handling of the last block that is less without encrypting the size of my message?

The description of that type depends on the Chaining Mode which you use The Chenning mode is that which defines how many times you invite AES primitive. And for the given input message, on what. The simplest chaining mode involves dividing the input data into 16-byte blocks and independently encrypting each of them; It is called ECB ("Electronic Code Book") and it is known for vulnerabilities (i.e., if two input blocks are equal, which are often in "real life" data , Then two related output blocks will be equal to one another, and no one else can see it).

Some chaining mode enlarges the data, meaning encrypted messages will be slightly larger than the input message. There are no other chaining modes (eg CTR), almost all secure chaining modes are required to deal with "initial value", which is a piece of data (usually the same size as a block), which should not be confidential, but For both the sender and the receiver, they should be separated, and some modes (like CBC) for each message are required to be equally random IV, while some other modes Rural will be happy to counter. It is customary to send encrypted messages as well as IV. You can get IV with heavy function as well as secret key.

These things are difficult, and it is difficult to know that you have done this right: safety can not be tested; A weak crypto system is compiled and runs just like any other application. Designing your cryptographic protocol is not recommended. Sure. There is no guarantee that employing strong priorities will be safeguarded.