[go: up one dir, main page]

aesni 0.2.1

AES (Rijndael) block ciphers implementation using AES-NI
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132

use core::{mem, fmt};

use u64x2::u64x2;
use super::{Aes128, Aes192, Aes256};

const BLOCK_SIZE: usize = 16;
const PAR_BLOCKS: usize = 8;
const PAR_BLOCKS_SIZE: usize = PAR_BLOCKS*BLOCK_SIZE;

#[inline(always)]
fn xor_block8(buf: &mut [u8], ctr: [u64x2; 8]) {
    assert_eq!(buf.len(), PAR_BLOCKS_SIZE);
    let t = unsafe {
        &mut *(buf.as_mut_ptr() as *mut [u64x2; PAR_BLOCKS])
    };
    for i in 0..PAR_BLOCKS {
        t[i].0 ^= ctr[i].0;
        t[i].1 ^= ctr[i].1;
    }
}

macro_rules! impl_ctr {
    ($name:ident, $cipher:ty, $key_size:expr, $doc:expr) => {
        #[doc=$doc]
        #[derive(Clone)]
        pub struct $name {
            ctr: u64x2,
            cipher: $cipher,

            leftover_buf: [u8; BLOCK_SIZE],
            leftover_cursor: usize,
        }

        impl $name {
            pub fn new(key: &[u8; $key_size], nonce: &[u8; BLOCK_SIZE]) -> Self {
                let ctr = u64x2::read(nonce).swap_bytes();
                let cipher = <$cipher>::init(key);
                Self{
                    ctr, cipher,
                    leftover_cursor: BLOCK_SIZE,
                    leftover_buf: [0u8; BLOCK_SIZE]
                }
            }

            #[inline]
            pub fn xor(&mut self, mut buf: &mut [u8]) {
                // process leftover bytes from the last call if any
                if self.leftover_cursor != BLOCK_SIZE {
                    // check if input buffer is large enough to be xor'ed
                    // with all leftover bytes
                    if buf.len() >= BLOCK_SIZE - self.leftover_cursor {
                        let n = self.leftover_cursor;
                        let leftover = &self.leftover_buf[n..];
                        let (r, l) = {buf}.split_at_mut(leftover.len());
                        buf = l;
                        for (a, b) in r.iter_mut().zip(leftover) { *a ^= *b; }
                        self.leftover_cursor = BLOCK_SIZE;
                    } else {
                        let s = self.leftover_cursor;
                        let leftover = &self.leftover_buf[s..s + buf.len()];
                        self.leftover_cursor += buf.len();

                        for (a, b) in buf.iter_mut().zip(leftover) { *a ^= *b; }
                        return;
                    }
                }

                // process 8 blocks at a time
                while buf.len() >= PAR_BLOCKS_SIZE {
                    let (r, l) = {buf}.split_at_mut(PAR_BLOCKS_SIZE);
                    buf = l;
                    xor_block8(r, self.next_block8());
                }

                // process one block at a time
                while buf.len() >= BLOCK_SIZE {
                    let (r, l) = {buf}.split_at_mut(BLOCK_SIZE);
                    buf = l;

                    let block = self.next_block();

                    let t = unsafe {
                        &mut *(r.as_mut_ptr() as *mut u64x2)
                    };
                    t.0 ^= block.0;
                    t.1 ^= block.1;
                }

                // process leftover bytes
                if buf.len() != 0 {
                    let block = self.next_block();
                    self.leftover_buf = unsafe {
                         mem::transmute::<u64x2, [u8; BLOCK_SIZE]>(block)
                    };
                    let n = buf.len();
                    self.leftover_cursor = n;
                    for (a, b) in buf.iter_mut().zip(&self.leftover_buf[..n]) {
                        *a ^= *b;
                    }
                }
            }

            #[inline(always)]
            fn next_block(&mut self) -> u64x2 {
                let mut block = self.ctr.swap_bytes();
                self.ctr.inc_be();
                self.cipher.encrypt_u64x2(&mut block);
                block
            }

            #[inline(always)]
            fn next_block8(&mut self) -> [u64x2; 8] {
                let mut block8 = [u64x2(0, 0); PAR_BLOCKS];
                let mut ctr = self.ctr;
                for i in 0..PAR_BLOCKS {
                    block8[i] = ctr.swap_bytes();
                    ctr.inc_be();
                }
                self.ctr = ctr;

                self.cipher.encrypt_u64x2_8(&mut block8);
                block8
            }
        }

        impl_opaque_debug!($name);
    }
}

impl_ctr!(CtrAes128, Aes128, 16, "AES128 in CTR mode");
impl_ctr!(CtrAes192, Aes192, 24, "AES192 in CTR mode");
impl_ctr!(CtrAes256, Aes256, 32, "AES256 in CTR mode");