This is the source code of the AES series created by What's a Creel. The video series can be found here. I do not take credit for this and I'm only posting it since it was requested in the comment section. However, I did implement the decryption portion and added a bit more context on what some of these functions do.
I tried to reorganize some of the code in a way that still closely resembles the original. It should be noted this is for ECE AES-128. For larger bit keys the process is very similar and mostly differs on the key expansion and number of rounds. If you are more curious I recommend you view this implementation. It helped me when trying to work out the decryption portion and supports different key sizes.
As mentioned in the beginning of the series this should not be used in any implementation and is for the sake of understanding the operations of AES. One type of attack mentioned by the author is cache-timing attacks where response times can leak information regarding the key. Many processors also include their own implementation of AES with a new instruction that vastly improves performance and according to current research should be safe from these types of attacks.
Another reason to not base any real world applications on this is the fact that AES-ECB is not semantically secure. Comparing two ciphertexts or looking for repetitive information within a single ciphertext can leak plaintext information. A good explanation can be found here.
make
Like in the video series the key is hardcoded and can be found in the aes_key.h file.
$ ./bin/enc -?
Usage: enc [OPTION...] message hex-print
Encrypts input message with ECB AES-128
-h, --hex-print Output encrypted message as hex
-m, --message=This is an AES encrypted message!
Message to encrypt.
-?, --help Give this help list
--usage Give a short usage message
Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.
- Binary output of test message
$ ./bin/enc
- Hex output of test message
$ ./bin/enc -h
- Enter your own message
$ ./bin/enc -m "This is a new message" -h
$ ./dec -?
Usage: dec [OPTION...] message hex-print
Decrypts input message with ECB AES-128
-m, --message=Input message as bytes
Message to decrypt.
-?, --help Give this help list
--usage Give a short usage message
Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.
- Decryption of hard coded test message
$ ./bin/dec
- Decrypt your own message read from binary
$ ./bin/dec -m "own message"