AES(Advanced Encryption Standard)

2.0 Block Ciphers

Block cipher - is one of the two common modern symmetric cipher types. It is distinguished from a stream cipher, because a b lock cipher performs operations on a chuck or blocks of plain text at once, whereas a stream cipher can operate on a single bit of plaintext at a time. The generated ciphertext has blocks equal to the number of blocks in plaintext and also has the same number of bits in each block as of plain text. Block cipher uses a symmetric key (the same key for encryption and decryption.
                   The foremost example of a modern block cipher is the Advanced Encryption Standard (AES) . AES is the primary cipher approved for use by the U.S. government to protect electronic data. It was certified in 2001, and has been something of a de facto standard cryptographic algorithm worldwide. It replaced the aging DES, also a block cipher, which was issued in 1977 . There are too many block ciphers to list them all, but DES and AES are the two most famous examples..
                   AES, encrypts 128 bit blocks with a key of predetermined length: 128, 192, or 256 bits. DES divides the plain text into the number of blocks, each of 64-bit. DES operates on one block of plain text at a time. Key of 56-bit is applied to each block of plain text to produce its corresponding ciphertext of 64-bit. During decryption also only one block of ciphertext is operated at a time to produce its corresponding block plain text. In DES the decryption algorithm is the same as the encryption one.

2.1 The AES Algorithm

This algorithm consists of First, dividing the data into blocks. Under this method of encryption, the first thing that happens is that your plaintext (which is the information that you want to be encrypted) is separated into blocks. The block size of AES is 128-bits, so it separates the data into a four-by-four column of sixteen bytes (there are eight bits in a byte and 16 x 8 = 128).
If your message was “welcome to projectfpga” the first block looks like this:

w          o          t           r
e          m          o           o
l          e                      j
c                     p           e

and the next block will be

c         g
t         a
f
p

We can see the algorithm flow likewise:

• Add round key
• Substitute bytes
• Shift rows
• Mix columns
• Add round key

This project is written in verilog and will consist of the logism circuit and a youtube tutorial.Watch this video by Shad luiter for an overview of what we will be accomplishing in this project.