aes-soft: use fixslicing for AES encryption (#176)

Fixslicing is presently defined for encryption only.

However, accelerating just encryption is still useful for AES-CTR.

Performance is improved by ~3X as measured on an Intel Core i9
(despite the fixslicing implementation being 32-bit only)

aes/aes-soft/benches/aes128.rs

@@ -2,7 +2,7 @@
 extern crate test;
 
 use aes_soft::cipher::{BlockCipher, NewBlockCipher};
-use aes_soft::{Aes128, Aes128Fixsliced};
+use aes_soft::Aes128;
 
 #[bench]
 pub fn aes128_encrypt(bh: &mut test::Bencher) {
@@ -40,18 +40,6 @@ pub fn aes128_encrypt8(bh: &mut test::Bencher) {
     bh.bytes = (input[0].len() * input.len()) as u64;
 }
 
-#[bench]
-pub fn aes128_encrypt2_fixsliced(bh: &mut test::Bencher) {
-    let cipher = Aes128Fixsliced::new(&Default::default());
-    let mut input = Default::default();
-
-    bh.iter(|| {
-        cipher.encrypt_blocks(&mut input);
-        test::black_box(&input);
-    });
-    bh.bytes = (input[0].len() * input.len()) as u64;
-}
-
 #[bench]
 pub fn aes128_decrypt8(bh: &mut test::Bencher) {
     let cipher = Aes128::new(&Default::default());

aes/aes-soft/benches/aes192.rs

@@ -2,7 +2,7 @@
 extern crate test;
 
 use aes_soft::cipher::{BlockCipher, NewBlockCipher};
-use aes_soft::{Aes192, Aes192Fixsliced};
+use aes_soft::Aes192;
 
 #[bench]
 pub fn aes192_encrypt(bh: &mut test::Bencher) {
@@ -40,18 +40,6 @@ pub fn aes192_encrypt8(bh: &mut test::Bencher) {
     bh.bytes = (input[0].len() * input.len()) as u64;
 }
 
-#[bench]
-pub fn aes192_encrypt2_fixsliced(bh: &mut test::Bencher) {
-    let cipher = Aes192Fixsliced::new(&Default::default());
-    let mut input = Default::default();
-
-    bh.iter(|| {
-        cipher.encrypt_blocks(&mut input);
-        test::black_box(&input);
-    });
-    bh.bytes = (input[0].len() * input.len()) as u64;
-}
-
 #[bench]
 pub fn aes192_decrypt8(bh: &mut test::Bencher) {
     let cipher = Aes192::new(&Default::default());

aes/aes-soft/benches/aes256.rs

@@ -2,7 +2,7 @@
 extern crate test;
 
 use aes_soft::cipher::{BlockCipher, NewBlockCipher};
-use aes_soft::{Aes256, Aes256Fixsliced};
+use aes_soft::Aes256;
 
 #[bench]
 pub fn aes256_encrypt(bh: &mut test::Bencher) {
@@ -40,18 +40,6 @@ pub fn aes256_encrypt8(bh: &mut test::Bencher) {
     bh.bytes = (input[0].len() * input.len()) as u64;
 }
 
-#[bench]
-pub fn aes256_encrypt2_fixsliced(bh: &mut test::Bencher) {
-    let cipher = Aes256Fixsliced::new(&Default::default());
-    let mut input = Default::default();
-
-    bh.iter(|| {
-        cipher.encrypt_blocks(&mut input);
-        test::black_box(&input);
-    });
-    bh.bytes = (input[0].len() * input.len()) as u64;
-}
-
 #[bench]
 pub fn aes256_decrypt8(bh: &mut test::Bencher) {
     let cipher = Aes256::new(&Default::default());

aes/aes-soft/src/bitslice.rs

@@ -21,26 +21,6 @@ pub trait AesOps {
     fn add_round_key(self, rk: &Self) -> Self;
 }
 
-pub fn encrypt_core<S: AesOps + Copy>(state: &S, sk: &[S]) -> S {
-    // Round 0 - add round key
-    let mut tmp = state.add_round_key(&sk[0]);
-
-    // Remaining rounds (except last round)
-    for i in 1..sk.len() - 1 {
-        tmp = tmp.sub_bytes();
-        tmp = tmp.shift_rows();
-        tmp = tmp.mix_columns();
-        tmp = tmp.add_round_key(&sk[i]);
-    }
-
-    // Last round
-    tmp = tmp.sub_bytes();
-    tmp = tmp.shift_rows();
-    tmp = tmp.add_round_key(&sk[sk.len() - 1]);
-
-    tmp
-}
-
 pub fn decrypt_core<S: AesOps + Copy>(state: &S, sk: &[S]) -> S {
     // Round 0 - add round key
     let mut tmp = state.add_round_key(&sk[sk.len() - 1]);