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

use block_buffer::byteorder::{ByteOrder, BE};
use block_buffer::BlockBuffer;
use digest::generic_array::typenum::{U32, U64};
use digest::generic_array::GenericArray;
use digest::{BlockInput, FixedOutput, Input, Reset};

use crate::consts::{IV, STATE_LEN};
use crate::utils::compress256;

type BlockSize = U64;
type Block = GenericArray<u8, BlockSize>;

#[derive(Clone)]
struct EngineState {
    h: [u32; STATE_LEN],
}

impl EngineState {
    fn new(h: &[u32; STATE_LEN]) -> EngineState {
        EngineState { h: *h }
    }

    pub fn process_block(&mut self, block: &Block) {
        let block = unsafe { &*(block.as_ptr() as *const [u8; 64]) };
        compress256(&mut self.h, block);
    }
}

#[derive(Clone)]
struct Engine {
    len: u64,
    buffer: BlockBuffer<BlockSize>,
    state: EngineState,
}

impl Engine {
    fn new(h: &[u32; STATE_LEN]) -> Engine {
        Engine {
            len: 0,
            buffer: Default::default(),
            state: EngineState::new(h),
        }
    }

    fn input(&mut self, input: &[u8]) {
        // Assumes that input.len() can be converted to u64 without overflow
        self.len += (input.len() as u64) << 3;
        let self_state = &mut self.state;
        self.buffer
            .input(input, |input| self_state.process_block(input));
    }

    fn finish(&mut self) {
        let self_state = &mut self.state;
        let l = self.len;
        self.buffer
            .len64_padding::<BE, _>(l, |b| self_state.process_block(b));
    }

    fn reset(&mut self, h: &[u32; STATE_LEN]) {
        self.len = 0;
        self.buffer.reset();
        self.state = EngineState::new(h);
    }
}

#[derive(Clone)]
pub struct Sm3 {
    engine: Engine,
}

impl Default for Sm3 {
    fn default() -> Self {
        Sm3 {
            engine: Engine::new(&IV),
        }
    }
}

impl BlockInput for Sm3 {
    type BlockSize = BlockSize;
}

impl Input for Sm3 {
    fn input<B: AsRef<[u8]>>(&mut self, input: B) {
        self.engine.input(input.as_ref());
    }
}

impl FixedOutput for Sm3 {
    type OutputSize = U32;

    fn fixed_result(mut self) -> GenericArray<u8, Self::OutputSize> {
        self.engine.finish();
        let mut out = GenericArray::default();
        BE::write_u32_into(&self.engine.state.h, out.as_mut_slice());
        out
    }
}

impl Reset for Sm3 {
    fn reset(&mut self) {
        self.engine.reset(&IV);
    }
}