From 7a9bf1d6e76adbf3ec0d85050c018d75b3879431 Mon Sep 17 00:00:00 2001
From: rsiddharth <s@ricketyspace.net>
Date: Tue, 17 Nov 2020 21:17:36 -0500
Subject: lib: aes: add AddRoundKey
---
lib/aes.go | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/lib/aes.go b/lib/aes.go
index a4c8ec2..389dc44 100644
--- a/lib/aes.go
+++ b/lib/aes.go
@@ -3,6 +3,30 @@
package lib
+func AddRoundKey(state, ks [][]byte) [][]byte {
+ if len(ks) != 4 {
+ return state
+ }
+ nb := 4
+
+ // Get tranpose of ks.
+ ks_t := make([][]byte, 4)
+ for i := 0; i < 4; i++ {
+ ks_t[i] = make([]byte, 4)
+ for j := 0; j < 4; j++ {
+ ks_t[i][j] = ks[j][i]
+ }
+ }
+
+ // Round key transformation.
+ for c := 0; c < nb; c++ {
+ for r := 0; r < 4; r++ {
+ state[r][c] = state[r][c] ^ ks_t[r][c]
+ }
+ }
+ return state
+}
+
// Makes and returns initial the state array from 16-byte input 'in'.
func MkState(in []byte) [][]byte {
if len(in) != 16 {
--
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