99 lines
3.0 KiB
Rust
99 lines
3.0 KiB
Rust
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//! SM3 block-level core (low-level internal type).
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//!
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//! Users should use [`Sm3`] from the crate root instead.
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use core::fmt;
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use digest::{
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HashMarker,
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block_api::{
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AlgorithmName, Block, BlockSizeUser, Buffer, BufferKindUser,
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Eager, FixedOutputCore, OutputSizeUser, UpdateCore,
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},
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typenum::{U32, U64, Unsigned},
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};
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use crate::compress;
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// ── Sm3Core ───────────────────────────────────────────────────────────────────
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/// Low-level SM3 block-processing core.
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///
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/// Implements the `digest::block_api` low-level traits so that the
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/// [`digest::buffer_fixed!`] macro can wrap it into a fully-featured [`Sm3`].
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#[derive(Clone)]
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pub struct Sm3Core {
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state: [u32; 8],
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/// Number of **complete** 64-byte blocks already compressed.
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block_len: u64,
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}
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impl HashMarker for Sm3Core {}
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impl BlockSizeUser for Sm3Core {
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/// SM3 processes 512-bit (64-byte) blocks.
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type BlockSize = U64;
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}
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impl BufferKindUser for Sm3Core {
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/// Eager: compress each full block immediately.
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type BufferKind = Eager;
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}
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impl OutputSizeUser for Sm3Core {
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/// SM3 produces a 256-bit (32-byte) digest.
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type OutputSize = U32;
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}
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impl Default for Sm3Core {
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fn default() -> Self {
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Self { state: compress::IV, block_len: 0 }
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}
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}
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impl digest::Reset for Sm3Core {
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fn reset(&mut self) {
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*self = Self::default();
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}
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}
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impl UpdateCore for Sm3Core {
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#[inline]
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fn update_blocks(&mut self, blocks: &[Block<Self>]) {
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// Reason: only complete blocks are counted here; the partial tail is
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// held by the surrounding BlockBuffer and counted in finalize.
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self.block_len += blocks.len() as u64;
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for block in blocks {
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// Reason: hybrid_array::Array<u8, U64> implements Deref<Target=[u8]>,
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// so we get a &[u8] slice then cast to &[u8; 64] via try_into.
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let b: &[u8; 64] = (&**block).try_into().unwrap();
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compress::compress(&mut self.state, b);
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}
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}
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}
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impl FixedOutputCore for Sm3Core {
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#[inline]
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fn finalize_fixed_core(&mut self, buffer: &mut Buffer<Self>, out: &mut digest::Output<Self>) {
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// Total bit length = (complete blocks × 64 + partial tail) × 8
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let bs = U64::U64;
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let bit_len = 8 * (buffer.get_pos() as u64 + bs * self.block_len);
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// GB/T 32905 §5.3.1 padding: 0x80, zeros, 64-bit big-endian bit count
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buffer.len64_padding_be(bit_len, |block| {
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let b: &[u8; 64] = (&**block).try_into().unwrap();
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compress::compress(&mut self.state, b);
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});
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// Serialize state as big-endian u32 words
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for (chunk, &word) in out.chunks_exact_mut(4).zip(self.state.iter()) {
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chunk.copy_from_slice(&word.to_be_bytes());
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}
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}
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}
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impl AlgorithmName for Sm3Core {
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fn write_alg_name(f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.write_str("Sm3")
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}
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}
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