Project 4
This project concerns implementing a simple variant of Galois Counter Mode (GCM). Please see the textbook Understanding Cryptography, p. 134. Take note of the textbook errata:
http://wiki.crypto.rub.de/Buch/en/download/Errata.pdf
Fix the missing parts of the code so that the output of modes.c is the following:
~/Crypto_Spring_18/proj4$ gcc *.c
~/Crypto_Spring_18/proj4$ ./a.out
plaintext: vote
ciphertext: 0x3D391509
tag: 0x8D
validating tag: valid
plaintext: outside
ciphertext: 0xC4C3B5BFBE8688
tag: 0xC4
validating tag: valid
plaintext: plate
ciphertext: 0xFBFAC0D8D2
tag: 0x45
validating tag: valid
plaintext: estate
ciphertext: 0xEEE5D5CDC3A7
tag: 0xAB
replacing tag with 0xAC
a.out: modes.c:160: main: Assertion `valid==VALID' failed.
validating tag: Aborted (core dumped)
