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use super::BlockCipher;
use byte_tools::{read_u64_be, write_u64_be};
use generic_array::GenericArray;
use generic_array::typenum::{U1, U8};
use core::fmt;
use consts::{SBOXES, SHIFTS};
#[derive(Copy, Clone)]
pub struct Des {
pub(crate) keys: [u64; 16],
}
fn delta_swap(a: u64, delta: u64, mask: u64) -> u64 {
let b = (a ^ (a >> delta)) & mask;
a ^ b ^ (b << delta)
}
fn pc1(mut key: u64) -> u64 {
key = delta_swap(key, 2, 0x3333000033330000);
key = delta_swap(key, 4, 0x0f0f0f0f00000000);
key = delta_swap(key, 8, 0x009a000a00a200a8);
key = delta_swap(key, 16, 0x00006c6c0000cccc);
key = delta_swap(key, 1, 0x1045500500550550);
key = delta_swap(key, 32, 0x00000000f0f0f5fa);
key = delta_swap(key, 8, 0x00550055006a00aa);
key = delta_swap(key, 2, 0x0000333330000300);
key & 0xFFFFFFFFFFFFFF00
}
fn pc2(key: u64) -> u64 {
let key = key.rotate_left(61);
let b1 = (key & 0x0021000002000000) >> 7;
let b2 = (key & 0x0008020010080000) << 1;
let b3 = key & 0x0002200000000000;
let b4 = (key & 0x0000000000100020) << 19;
let b5 = (key.rotate_left(54) & 0x0005312400000011)
.wrapping_mul(0x0000000094200201) & 0xea40100880000000;
let b6 = (key.rotate_left(7) & 0x0022110000012001)
.wrapping_mul(0x0001000000610006) & 0x1185004400000000;
let b7 = (key.rotate_left(6) & 0x0000520040200002)
.wrapping_mul(0x00000080000000c1) & 0x0028811000200000;
let b8 = (key & 0x01000004c0011100)
.wrapping_mul(0x0000000000004284) & 0x0400082244400000;
let b9 = (key.rotate_left(60) & 0x0000000000820280)
.wrapping_mul(0x0000000000089001) & 0x0000000110880000;
let b10 = (key.rotate_left(49) & 0x0000000000024084)
.wrapping_mul(0x0000000002040005) & 0x000000000a030000;
b1 | b2 | b3 | b4 | b5 | b6 | b7 | b8 | b9 | b10
}
fn fp(mut message: u64) -> u64 {
message = delta_swap(message, 24, 0x000000FF000000FF);
message = delta_swap(message, 24, 0x00000000FF00FF00);
message = delta_swap(message, 36, 0x000000000F0F0F0F);
message = delta_swap(message, 18, 0x0000333300003333);
delta_swap(message, 9, 0x0055005500550055)
}
fn ip(mut message: u64) -> u64 {
message = delta_swap(message, 9, 0x0055005500550055);
message = delta_swap(message, 18, 0x0000333300003333);
message = delta_swap(message, 36, 0x000000000F0F0F0F);
message = delta_swap(message, 24, 0x00000000FF00FF00);
delta_swap(message, 24, 0x000000FF000000FF)
}
fn e(block: u64) -> u64 {
const BLOCK_LEN: usize = 32;
const RESULT_LEN: usize = 48;
let b1 = (block << (BLOCK_LEN - 1)) & 0x8000000000000000;
let b2 = (block >> 1) & 0x7C00000000000000;
let b3 = (block >> 3) & 0x03F0000000000000;
let b4 = (block >> 5) & 0x000FC00000000000;
let b5 = (block >> 7) & 0x00003F0000000000;
let b6 = (block >> 9) & 0x000000FC00000000;
let b7 = (block >> 11) & 0x00000003F0000000;
let b8 = (block >> 13) & 0x000000000FC00000;
let b9 = (block >> 15) & 0x00000000003E0000;
let b10 = (block >> (RESULT_LEN - 1)) & 0x0000000000010000;
b1 | b2 | b3 | b4 | b5 | b6 | b7 | b8 | b9 | b10
}
fn p(block: u64) -> u64 {
let block = block.rotate_left(44);
let b1 = (block & 0x0000000000200000) << 32;
let b2 = (block & 0x0000000000480000) << 13;
let b3 = (block & 0x0000088000000000) << 12;
let b4 = (block & 0x0000002020120000) << 25;
let b5 = (block & 0x0000000442000000) << 14;
let b6 = (block & 0x0000000001800000) << 37;
let b7 = (block & 0x0000000004000000) << 24;
let b8 = (block & 0x0000020280015000).wrapping_mul(0x0000020080800083) & 0x02000a6400000000;
let b9 = (block.rotate_left(29) & 0x01001400000000aa).wrapping_mul(0x0000210210008081) & 0x0902c01200000000;
let b10 = (block & 0x0000000910040000).wrapping_mul(0x0000000c04000020) & 0x8410010000000000;
b1 | b2 | b3 | b4 | b5 | b6 | b7 | b8 | b9 | b10
}
pub(crate) fn gen_keys(key: u64) -> [u64; 16] {
let mut keys: [u64; 16] = [ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
let key = pc1(key);
let key = key >> 8;
let mut c = key >> 28;
let mut d = key & 0x0FFFFFFF;
for i in 0..16 {
c = rotate(c, SHIFTS[i]);
d = rotate(d, SHIFTS[i]);
keys[i] = pc2(((c << 28) | d) << 8 );
}
keys
}
fn rotate(mut val: u64, shift: u8) -> u64 {
let top_bits = val >> (28 - shift);
val <<= shift;
(val | top_bits) & 0x0FFFFFFF
}
fn round(input: u64, key: u64) -> u64 {
let l = input & (0xFFFF_FFFF << 32);
let r = input << 32;
r | ((f(r, key) ^ l) >> 32)
}
fn f(input: u64, key: u64) -> u64 {
let mut val = e(input as u64);
val ^= key;
val = apply_sboxes(val);
p(val)
}
fn apply_sboxes(input: u64) -> u64 {
let mut output: u64 = 0;
for i in 0..8 {
let sbox = SBOXES[i];
let val = (input >> (58 - (i * 6))) & 0x3F;
output |= (sbox[val as usize] as u64) << (60 - (i * 4));
}
output
}
impl Des {
pub(crate) fn encrypt(&self, mut data: u64) -> u64 {
data = ip(data);
for key in self.keys.iter() {
data = round(data, *key);
}
fp((data << 32) | (data >> 32))
}
pub(crate) fn decrypt(&self, mut data: u64) -> u64 {
data = ip(data);
for key in self.keys.iter().rev() {
data = round(data, *key);
}
fp((data << 32) | (data >> 32))
}
}
impl BlockCipher for Des {
type KeySize = U8;
type BlockSize = U8;
type ParBlocks = U1;
fn new(key: &GenericArray<u8, U8>) -> Self {
Des { keys: gen_keys(read_u64_be(key)) }
}
fn encrypt_block(&self, block: &mut GenericArray<u8, U8>) {
let data = read_u64_be(block);
write_u64_be(block, self.encrypt(data));
}
fn decrypt_block(&self, block: &mut GenericArray<u8, U8>) {
let data = read_u64_be(block);
write_u64_be(block, self.decrypt(data));
}
}
impl_opaque_debug!(Des);