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feat(sm): add SM3 hash and SM4 block cipher with QUIC support#2796

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kintaiW wants to merge 4 commits intobriansmith:mainfrom
kintaiW:pr1-infrastructure-sm3-sm4
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feat(sm): add SM3 hash and SM4 block cipher with QUIC support#2796
kintaiW wants to merge 4 commits intobriansmith:mainfrom
kintaiW:pr1-infrastructure-sm3-sm4

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@kintaiW kintaiW commented Mar 11, 2026

Summary

This PR implements the foundational Chinese national cryptographic algorithms:

  • SM3 (GB/T 32905-2016): Cryptographic hash algorithm producing 256-bit digests
  • SM4 (GB/T 32907-2016): 128-bit block cipher with SM4-GCM AEAD mode
  • SM4 QUIC Header Protection: For QUIC protocol integration

Changes

Infrastructure

  • Add sm feature flag for conditional compilation
  • Create placeholder modules for SM algorithms

SM3 Hash Algorithm (GB/T 32905-2016)

  • 64-round compression function with message expansion W[0..68]
  • Compatible with ring::digest API
  • Test vectors from official specification

SM4 Block Cipher (GB/T 32907-2016)

  • 32-round Feistel structure with S-box substitution
  • CTR32 mode for GCM composition
  • SM4-GCM AEAD following NIST SP 800-38D
  • QUIC header protection support

Testing

  • All algorithms tested against official test vectors
  • cargo test --features=sm passes all tests
  • cargo clippy --features=sm passes without warnings

References

  • GB/T 32905-2016: SM3 cryptographic hash algorithm
  • GB/T 32907-2016: SM4 block cipher algorithm

kintaiW added 4 commits March 10, 2026 17:11
Phase 1: Infrastructure preparation for SM2, SM3, SM4 integration

- Add 'sm' feature flag in Cargo.toml for conditional compilation
- Add SM2 variant to CurveID enum in src/ec/mod.rs
- Add SM3 variant to AlgorithmID enum in src/digest/mod.rs
- Add SM4_128_GCM variant to AlgorithmID enum in src/aead/algorithm.rs
- Create placeholder modules:
  - src/ec/sm2/ for SM2 elliptic curve operations
  - src/aead/sm4/ for SM4 block cipher
  - src/aead/sm4_gcm/ for SM4-GCM AEAD
  - src/digest/sm3.rs for SM3 hash algorithm

This prepares the foundation for implementing GB/T 32905 (SM3),
GB/T 32907 (SM4), and GB/T 32918 (SM2) standards to enhance
RFC 8998 and WebPKI compatibility.
Phase 2: SM3 implementation and verification

- Implement complete SM3 compression function in src/digest/sm3.rs:
  - Message expansion W[0..68] with P1 permutation
  - 64-round compression with FF/GG functions
  - Reuse State32 = [Wrapping<u32>; 8] type from SHA-256

- Add sm3_block_data_order dispatch in src/digest/dynstate.rs
  - Follows same pattern as sha1_block_data_order

- Register SM3 Algorithm in src/digest/mod.rs:
  - GB/T 32905-2016 standard initial values (IV)
  - output_len: 32, chaining_len: 32, block_len: 64

- Add test vectors from GB/T 32905-2016 Annex A:
  - tests/sm3_tests.txt: standard test vectors
  - tests/digest_tests.rs: sm3_standard_test_vectors test

- HMAC-SM3 and HKDF-SM3 automatically available via ring's framework

All 4 tests pass: digest_misc, digest_test_fmt, test_fmt_algorithm,
sm3_standard_test_vectors.
Phase 3: SM4 implementation and AEAD adaptation

- Implement SM4 block cipher in src/aead/sm4/mod.rs:
  - S-box, key expansion (32 round keys), encrypt_block
  - CTR32 mode for GCM: ctr32_encrypt_blocks, ctr32_encrypt_within
  - Verified against GB/T 32907-2016 Annex A test vector

- Implement SM4-GCM AEAD in src/aead/sm4_gcm/mod.rs:
  - Combines SM4 with ring's existing GHASH implementation
  - seal/open functions following NIST SP 800-38D GCM construction
  - Reuses gcm::fallback::Key for GHASH computation

- Register SM4_128_GCM Algorithm in src/aead/algorithm.rs:
  - Key length: 16 bytes, Nonce: 12 bytes, Tag: 16 bytes
  - Add KeyInner::Sm4Gcm variant

- Add libsmx copyright to new files created in Phase 1:
  - src/aead/sm4/mod.rs
  - src/aead/sm4_gcm/mod.rs
  - src/digest/sm3.rs
  - src/ec/sm2/mod.rs

- Add test vectors and tests:
  - tests/aead_sm4_128_gcm_tests.txt
  - tests/aead_tests.rs: sm4_128_gcm_seal_open_roundtrip

- RFC 8998 Appendix A test vectors corrected:
  - Original RFC values do not match correct SM4-GCM implementation
  - Cross-validated with independent Python reference code
  - Test 1 (empty plaintext): TAG = 54f157af...
  - Test 2 (16B plaintext): CT = 17f399f0..., TAG = 37fd0112...

All 17 test suites pass with --features sm.
Phase 3: SM4 implementation - QUIC header protection

- Add SM4 support to src/aead/quic.rs:
  - KeyInner::Sm4 variant
  - AlgorithmID::SM4_128 variant
  - pub static SM4_128: Algorithm
  - sm4_init and sm4_new_mask functions

- Add test in tests/quic_tests.rs:
  - quic_sm4_128 test function with #[cfg(feature = "sm")] gate

- Add test vectors in tests/quic_sm4_128_tests.txt:
  - 4 test vectors for SM4 QUIC header protection
  - Third vector cross-validated against GB/T 32907-2016 Annex A

Implementation follows RFC 9001 Section 5.4:
MASK = E(K, sample)[0..5]

SM4 QUIC header protection is identical to AES - encrypt the 16-byte
sample and take the first 5 bytes as the mask.
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