diff options
Diffstat (limited to 'src/lib.rs')
| -rw-r--r-- | src/lib.rs | 63 |
1 files changed, 37 insertions, 26 deletions
@@ -642,11 +642,11 @@ fn cipher_aez_core<A: AsRef<[u8]>, T: IntoIterator<Item = A>>( match mode { Mode::Encipher => { s_x = m_x ^ delta ^ x ^ e(0, 1, aez, m_y); - s_y = m_y ^ e(-1, 1, aez, s_x); + s_y = m_y ^ e_neg(1, aez, s_x); } Mode::Decipher => { s_x = m_x ^ delta ^ x ^ e(0, 2, aez, m_y); - s_y = m_y ^ e(-1, 2, aez, s_x); + s_y = m_y ^ e_neg(2, aez, s_x); } } let s = s_x ^ s_y; @@ -659,12 +659,12 @@ fn cipher_aez_core<A: AsRef<[u8]>, T: IntoIterator<Item = A>>( match d { 0 => (), _ if d <= 127 => { - c_u = (m_u ^ e(-1, 4, aez, s)).clip(d); + c_u = (m_u ^ e_neg(4, aez, s)).clip(d); y = y ^ e(0, 4, aez, c_u.pad(d)); } _ => { - c_u = m_u ^ e(-1, 4, aez, s); - c_v = (m_v ^ e(-1, 5, aez, s)).clip(len_v); + c_u = m_u ^ e_neg(4, aez, s); + c_v = (m_v ^ e_neg(5, aez, s)).clip(len_v); y = y ^ e(0, 4, aez, c_u); y = y ^ e(0, 5, aez, c_v.pad(len_v)); } @@ -673,11 +673,11 @@ fn cipher_aez_core<A: AsRef<[u8]>, T: IntoIterator<Item = A>>( let (c_x, c_y); match mode { Mode::Encipher => { - c_y = s_x ^ e(-1, 2, aez, s_y); + c_y = s_x ^ e_neg(2, aez, s_y); c_x = s_y ^ delta ^ y ^ e(0, 2, aez, c_y); } Mode::Decipher => { - c_y = s_x ^ e(-1, 1, aez, s_y); + c_y = s_x ^ e_neg(1, aez, s_y); c_x = s_y ^ delta ^ y ^ e(0, 1, aez, c_y); } } @@ -728,13 +728,13 @@ fn aez_prf<A: AsRef<[u8]>, T: IntoIterator<Item = A>>(aez: &Aez, tweaks: T, buff let delta = aez_hash(aez, tweaks); for chunk in buffer.chunks_exact_mut(16) { let chunk: &mut [u8; 16] = chunk.try_into().unwrap(); - let block = e(-1, 3, aez, delta ^ index); + let block = e_neg(3, aez, delta ^ index); (block ^ Block::from(*chunk)).write_to(chunk); index.count_up(); } let suffix_start = buffer.len() - buffer.len() % 16; let chunk = &mut buffer[suffix_start..]; - let block = e(-1, 3, aez, delta ^ index); + let block = e_neg(3, aez, delta ^ index); for (a, b) in chunk.iter_mut().zip(block.bytes().iter()) { *a ^= *b; } @@ -746,16 +746,14 @@ fn aez_prf<A: AsRef<[u8]>, T: IntoIterator<Item = A>>(aez: &Aez, tweaks: T, buff /// temporary values and makes it much faster to compute E_K^{j, i+1}, E_K^{j, i+2}, ... struct E<'a> { aez: &'a Aez, - i: u32, + i: usize, kj_t_j: Block, ki_p_i: Block, } impl<'a> E<'a> { /// Create a new "suspended" computation of E_K^{j,i}. - fn new(j: i32, i: u32, aez: &'a Aez) -> Self { - assert!(j >= 0); - let j: u32 = j.try_into().expect("j was negative"); + fn new(j: usize, i: usize, aez: &'a Aez) -> Self { let exponent = if i % 8 == 0 { i / 8 } else { i / 8 + 1 }; E { aez, @@ -767,7 +765,7 @@ impl<'a> E<'a> { /// Complete this computation to evaluate E_K^{j,i}(block). fn eval(&self, block: Block) -> Block { - let delta = self.kj_t_j ^ self.ki_p_i ^ self.aez.key_l_multiples[self.i as usize % 8]; + let delta = self.kj_t_j ^ self.ki_p_i ^ self.aez.key_l_multiples[self.i % 8]; self.aez.aes.aes4(block ^ delta) } @@ -862,17 +860,18 @@ impl<'a> Iterator for Eiter<'a> { } /// Shorthand to get E_K^{j,i}(block) -fn e(j: i32, i: u32, aez: &Aez, block: Block) -> Block { - if j == -1 { - let delta = if i < 8 { - aez.key_l_multiples[i as usize] - } else { - aez.key_l * i - }; - aez.aes.aes10(block ^ delta) +fn e(j: usize, i: usize, aez: &Aez, block: Block) -> Block { + E::new(j, i, aez).eval(block) +} + +/// Computes E_K^{-1,i}(block) +fn e_neg(i: usize, aez: &Aez, block: Block) -> Block { + let delta = if i < 8 { + aez.key_l_multiples[i] } else { - E::new(j, i, aez).eval(block) - } + aez.key_l * i + }; + aez.aes.aes10(block ^ delta) } fn split_key(key: &Key) -> (Block, Block, Block) { @@ -920,7 +919,7 @@ pub mod primitives { super::aez_prf(aez, tweaks, buffer) } - pub fn e(j: i32, i: u32, aez: &Aez, block: [u8; 16]) -> [u8; 16] { + pub fn e(j: usize, i: usize, aez: &Aez, block: [u8; 16]) -> [u8; 16] { super::e(j, i, aez, Block::from(block)).bytes() } } @@ -949,7 +948,19 @@ mod test { let a = hex::decode(a).unwrap(); let a = Block::from_slice(&a); let b = hex::decode(b).unwrap(); - assert_eq!(&e(*j, *i, &aez, a).bytes(), b.as_slice(), "{name}"); + if *j >= 0 { + assert_eq!( + &e((*j).try_into().unwrap(), (*i).try_into().unwrap(), &aez, a).bytes(), + b.as_slice(), + "{name}" + ); + } else { + assert_eq!( + &e_neg((*i).try_into().unwrap(), &aez, a).bytes(), + b.as_slice(), + "{name}" + ); + } } } |