linear_cryptanalysis

commit 70579322b5f819dd1854e434410506cc12c31dab
parent 24e3768742d0b98e845a2d8dfc87a3307c2321cb
Author: superpozycja <anna@superpozycja.net>
Date:   Thu, 12 Sep 2024 13:25:40 +0200

prepare round functions - not all yet

Diffstat:
A
src/lib.rs
 | 
36
++++++++++++++++++++++++++++++++++++
M
src/main.rs
 | 
4
++++

2 files changed, 40 insertions(+), 0 deletions(-)
diff --git a/src/lib.rs b/src/lib.rs
@@ -0,0 +1,36 @@
+use std::ops::Shl;
+use std::ops::Shr;
+
+/* this can be side channeled i think */
+static s_box: [u8; 16] = 
+    [0xe, 0x4, 0xd, 0x1, 0x2, 0xf, 0xb, 0x8,
+     0x3, 0xa, 0x6, 0xc, 0x5, 0x9, 0x0, 0x7];
+
+fn sub_byte(x: u8) -> u8 {
+    let mut res: u8 = 0;
+    res += s_box[(x & 0x0f) as usize];
+    let x = x >> 4;
+    res += s_box[(x & 0x0f) as usize] << 4;
+
+    res
+}
+
+fn xor(x: &mut [u8; 2], y: &[u8; 2]) {
+    x[0] ^= y[0];
+    x[1] ^= y[1];
+}
+
+fn sub(x: &mut [u8; 2]) {
+    x[0] = sub_byte(x[0]);
+    x[1] = sub_byte(x[1]);
+}
+
+pub fn encrypt(pt: &[u8; 2], key: &[u8; 2]) -> [u8; 2] {
+    println!("encrypting");
+    let mut ct = pt.clone();
+    println!("{:#04x}{:02x}", ct[0], ct[1]);
+    xor(&mut ct, key);
+    println!("{:#04x}{:02x}", ct[0], ct[1]);
+    sub(&mut ct);
+    ct
+}
diff --git a/src/main.rs b/src/main.rs
@@ -1,3 +1,7 @@
+use linear_cryptanalysis as la;
+
 fn main() {
     println!("Hello, world!");
+    let ct = la::encrypt(b"ab", b"xy");
+    println!("ciphertext = {:#04x}{:02x}", ct[0], ct[1])
 }