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
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179

//! SHA-256

use crate::consts::{H224, H256, STATE_LEN};
use block_buffer::{
    byteorder::{ByteOrder, BE},
    BlockBuffer,
};
use digest::impl_write;
use digest::{
    consts::{U28, U32, U64},
    generic_array::GenericArray,
};
use digest::{BlockInput, FixedOutputDirty, Reset, Update};

#[cfg(not(feature = "asm"))]
use crate::sha256_utils::compress256;

#[cfg(feature = "asm")]
use sha2_asm::compress256;

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

/// A structure that represents that state of a digest computation for the
/// SHA-2 512 family of digest functions
#[derive(Clone)]
struct Engine256State {
    h: [u32; 8],
}

impl Engine256State {
    fn new(h: &[u32; STATE_LEN]) -> Engine256State {
        Engine256State { h: *h }
    }

    #[cfg(not(feature = "asm-aarch64"))]
    pub fn process_block(&mut self, block: &Block) {
        let block = unsafe { &*(block.as_ptr() as *const [u8; 64]) };
        compress256(&mut self.h, block);
    }

    #[cfg(feature = "asm-aarch64")]
    pub fn process_block(&mut self, block: &Block) {
        let block = unsafe { &*(block.as_ptr() as *const [u8; 64]) };
        // TODO: Replace this platform-specific call with is_aarch64_feature_detected!("sha2") once
        // that macro is stabilised and https://github.com/rust-lang/rfcs/pull/2725 is implemented
        // to let us use it on no_std.
        if ::aarch64::sha2_supported() {
            compress256(&mut self.h, block);
        } else {
            ::sha256_utils::compress256(&mut self.h, block);
        }
    }
}

/// A structure that keeps track of the state of the Sha-256 operation and
/// contains the logic necessary to perform the final calculations.
#[derive(Clone)]
struct Engine256 {
    len: u64,
    buffer: BlockBuffer<BlockSize>,
    state: Engine256State,
}

impl Engine256 {
    fn new(h: &[u32; STATE_LEN]) -> Engine256 {
        Engine256 {
            len: 0,
            buffer: Default::default(),
            state: Engine256State::new(h),
        }
    }

    fn update(&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 = Engine256State::new(h);
    }
}

/// The SHA-256 hash algorithm with the SHA-256 initial hash value.
#[derive(Clone)]
pub struct Sha256 {
    engine: Engine256,
}

impl Default for Sha256 {
    fn default() -> Self {
        Sha256 {
            engine: Engine256::new(&H256),
        }
    }
}

impl BlockInput for Sha256 {
    type BlockSize = BlockSize;
}

impl Update for Sha256 {
    fn update(&mut self, input: impl AsRef<[u8]>) {
        self.engine.update(input.as_ref());
    }
}

impl FixedOutputDirty for Sha256 {
    type OutputSize = U32;

    fn finalize_into_dirty(&mut self, out: &mut digest::Output<Self>) {
        self.engine.finish();
        BE::write_u32_into(&self.engine.state.h, out.as_mut_slice());
    }
}

impl Reset for Sha256 {
    fn reset(&mut self) {
        self.engine.reset(&H256);
    }
}

/// The SHA-256 hash algorithm with the SHA-224 initial hash value. The result
/// is truncated to 224 bits.
#[derive(Clone)]
pub struct Sha224 {
    engine: Engine256,
}

impl Default for Sha224 {
    fn default() -> Self {
        Sha224 {
            engine: Engine256::new(&H224),
        }
    }
}

impl BlockInput for Sha224 {
    type BlockSize = BlockSize;
}

impl Update for Sha224 {
    fn update(&mut self, input: impl AsRef<[u8]>) {
        self.engine.update(input.as_ref());
    }
}

impl FixedOutputDirty for Sha224 {
    type OutputSize = U28;

    fn finalize_into_dirty(&mut self, out: &mut digest::Output<Self>) {
        self.engine.finish();
        BE::write_u32_into(&self.engine.state.h[..7], out.as_mut_slice());
    }
}

impl Reset for Sha224 {
    fn reset(&mut self) {
        self.engine.reset(&H224);
    }
}

impl_opaque_debug!(Sha224);
impl_opaque_debug!(Sha256);

impl_write!(Sha224);
impl_write!(Sha256);