feat(aes): generate subkeys

aes/src/constants.rs

@@ -1 +1,80 @@
 // AES Constants
+pub const S_BOXES: [[u8; 16]; 16] = [
+    [
+        0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB,
+        0x76,
+    ],
+    [
+        0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72,
+        0xC0,
+    ],
+    [
+        0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31,
+        0x15,
+    ],
+    [
+        0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2,
+        0x75,
+    ],
+    [
+        0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F,
+        0x84,
+    ],
+    [
+        0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58,
+        0xCF,
+    ],
+    [
+        0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F,
+        0xA8,
+    ],
+    [
+        0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3,
+        0xD2,
+    ],
+    [
+        0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19,
+        0x73,
+    ],
+    [
+        0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B,
+        0xDB,
+    ],
+    [
+        0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4,
+        0x79,
+    ],
+    [
+        0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE,
+        0x08,
+    ],
+    [
+        0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B,
+        0x8A,
+    ],
+    [
+        0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D,
+        0x9E,
+    ],
+    [
+        0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28,
+        0xDF,
+    ],
+    [
+        0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB,
+        0x16,
+    ],
+];
+
+pub const RCON: [u32; 10] = [
+    0x0100_0000,
+    0x0200_0000,
+    0x0400_0000,
+    0x0800_0000,
+    0x1000_0000,
+    0x2000_0000,
+    0x4000_0000,
+    0x8000_0000,
+    0x1B00_0000,
+    0x3600_0000,
+];

aes/src/key/expanded.rs

@@ -0,0 +1,5 @@
+use crate::secret_key;
+
+secret_key! {
+    pub struct ExpandedKey(u32, 32, 0xFFFF_FFFF);
+}

aes/src/key/mod.rs

@@ -1,4 +1,5 @@
 mod aes_key;
+mod expanded;
 mod secret_key;
 mod subkey;
 mod subkeys;

aes/src/key/secret_key.rs

@@ -15,7 +15,7 @@ macro_rules! secret_key {
     $vis:vis struct $name:ident ( $int:tt, $bits:expr, $mask:expr );
 ) => {
         $(#[$meta])*
-        #[derive(::zeroize::ZeroizeOnDrop, Default)]
+        #[derive(Default, Clone, Copy)]
         $vis struct $name($int);
 
         impl $name {

aes/src/key/subkey.rs

@@ -1,4 +1,5 @@
-use crate::key::secret_key;
+use crate::key::{expanded::ExpandedKey, secret_key};
+use std::ops::BitXor;
 
 secret_key! {
     /// A single AES round subkey
@@ -10,4 +11,34 @@ impl Subkey {
     pub const fn zero() -> Self {
         Self(0)
     }
+
+    /// Shifts the bits to the left by a specified amount, `n`,
+    /// wrapping the truncated bits to the end of the resulting integer.
+    ///
+    /// Please note this isn't the same operation as the `<<` shifting operator!
+    pub const fn rotate_left(self, n: u32) -> Self {
+        Self(self.0.rotate_left(n))
+    }
+
+    /// Shifts the bits to the right by a specified amount, `n`,
+    /// wrapping the truncated bits to the beginning of the resulting integer.
+    ///
+    /// Please note this isn't the same operation as the `>>` shifting operator!
+    pub const fn rotate_right(self, n: u32) -> Self {
+        Self(self.0.rotate_right(n))
+    }
+}
+
+impl BitXor<ExpandedKey> for Subkey {
+    type Output = Self;
+    fn bitxor(self, rhs: ExpandedKey) -> Self::Output {
+        Self(self.0 ^ rhs.as_u32())
+    }
+}
+
+impl BitXor for Subkey {
+    type Output = Self;
+    fn bitxor(self, rhs: Self) -> Self::Output {
+        Self(self.0 ^ rhs.0)
+    }
 }

aes/src/key/subkeys.rs

@@ -1,4 +1,7 @@
-use crate::key::{Key, subkey::Subkey};
+use crate::{
+    constants::{RCON, S_BOXES},
+    key::{Key, expanded::ExpandedKey, subkey::Subkey},
+};
 use std::{
     fmt::Debug,
     iter::Rev,
@@ -6,14 +9,32 @@ use std::{
     slice::{Iter, IterMut},
 };
 
+const SUBKEY_COUNT: usize = 44;
+
 // #[derive(Default)]
-pub struct Subkeys([Subkey; 44]);
+pub struct Subkeys([Subkey; SUBKEY_COUNT]);
 
 impl Subkeys {
     /// Generates 44 round subkeys from the given key.
     #[must_use]
     pub fn from_key(key: &Key) -> Self {
-        todo!()
+        let mut subkeys = [const { Subkey::zero() }; 44];
+
+        // Load initial key
+        for (idx, &key) in key.as_2d().iter().enumerate() {
+            subkeys[idx] = Subkey::from_u32(u32::from_be_bytes(key));
+        }
+
+        for (round, &rcon) in RCON.iter().enumerate() {
+            let idx = round * 4 + 4;
+
+            subkeys[idx + 0] = subkeys[idx - 4] ^ expand(&subkeys[idx - 1], rcon);
+            subkeys[idx + 1] = subkeys[idx] ^ subkeys[idx - 3];
+            subkeys[idx + 2] = subkeys[idx + 1] ^ subkeys[idx - 2];
+            subkeys[idx + 3] = subkeys[idx + 2] ^ subkeys[idx - 1];
+        }
+
+        Self(subkeys)
     }
 
     /// Returns an iterator over the subkeys.
@@ -61,6 +82,25 @@ impl Debug for Subkeys {
     }
 }
 
+const fn expand(subkey: &Subkey, rcon: u32) -> ExpandedKey {
+    let word = subkey.rotate_left(8).as_u32();
+
+    let b0 = sbox_lookup(word >> 24);
+    let b1 = sbox_lookup(word >> 16);
+    let b2 = sbox_lookup(word >> 8);
+    let b3 = sbox_lookup(word);
+    let substituted = (b0 << 24) | (b1 << 16) | (b2 << 8) | b3;
+    ExpandedKey::from_u32(substituted ^ rcon)
+}
+
+const fn sbox_lookup(byte: u32) -> u32 {
+    const MASK: u32 = 0xFF;
+    let row = ((byte & MASK) as usize) >> 4;
+    let col = ((byte & MASK) as usize) & 0xF;
+
+    S_BOXES[row][col] as u32
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

aes/src/lib.rs

@@ -2,5 +2,6 @@ mod aes;
 mod block;
 mod constants;
 mod key;
+mod utils;
 
 pub use {aes::Aes, block::Block128};

aes/src/utils.rs

@@ -0,0 +1,28 @@
+/// Generic bit permutation for DES specification.
+/// DES uses 1-based positioning where bit 1 is the leftmost (MSB) and bit 64 is the rightmost (LSB).
+/// This function handles this correctly for arbitrary input/output sizes.
+///
+/// # Arguments
+/// - `input` - The input value (treated as a bitfield of `input_bits` size)
+/// - `input_bits` - Number of meaningful bits in the input (1-64)
+/// - `output_bits` - Number of bits in the output (1-64)
+/// - `position_table` - Table of 1-based positions (1 to `input_bits`) where each output bit comes from.
+///   The table should have `output_bits` entries. For each entry i (0-based), `position_table`[i] indicates
+///   which input bit (1-based) should go to the i-th output bit position (from MSB to LSB).
+#[must_use]
+pub fn permutate(
+    input: u64,
+    input_bit_amount: u64,
+    output_bit_amount: u64,
+    position_table: &[u8],
+) -> u64 {
+    position_table
+        .iter()
+        .enumerate()
+        .fold(0, |acc, (idx, &input_pos_1based)| {
+            let input_bit_pos = input_bit_amount - u64::from(input_pos_1based);
+            let bit_value = (input >> input_bit_pos) & 1;
+            let output_bit_pos = output_bit_amount - 1 - (idx as u64);
+            acc | (bit_value << output_bit_pos)
+        })
+}

des/src/lib.rs

@@ -1,7 +1,7 @@
 mod block;
-pub(crate) mod constants;
+pub mod constants;
 mod des;
 mod key;
-pub(crate) mod utils;
+pub mod utils;
 
 pub use {block::Block64, des::Des};