Add SLH-DSA Support

[aidangarske]

• Add FIPS 205 SLH-DSA support for all 12 parameter sets.
• Implement key management, signatures, encoders, and decoders.
• Support pure and external message encodings.
• Support deterministic and seeded test operations.
• Serialize operations that share mutable wolfSSL key state.
• Support signing builds and verify-only wolfSSL builds.
• Add OpenSSL KAT, interoperability, version-matrix, and unit coverage.
• Pass all 20 SLH-DSA unit tests and 497 OpenSSL KAT vectors.
• fixes the docker confusion and merges to main docker
• Adds more osp intgration tests for mldsa, mlkem, slh-dsa
• Adds simple example for PQC
• depends on Encrypt PKCS#8 keys when a cipher is set on the PrivateKeyInfo encoder #453 which needs merged first
• depends on Add libacvp PQC test coverage osp#351
• Docs Document the wolfProvider post-quantum build options and defines documentation#274
• revert osp patch to point to osp master

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[Frauschi]

🐺 Skoll Code Review

Overall recommendation: REQUEST_CHANGES
Findings: 12 total — 5 posted, 7 skipped

Posted findings

• [High] openssl_example.c rewrite hard-fails on the IDE/Android and IDE/XCODE flows — examples/openssl_example.c:47-75 (duplicated in examples/pqc_openssl_example.c:225-238)
• [Medium] KAT vector accounting: the verify-only SLH-DSA KAT can pass with zero vectors, the exact 3099 count is pinned against a floating OpenSSL tag, and the old 2602 comment was left behind — .github/workflows/wolfssl-versions-pqc.yml:204-214
• [Medium] WOLFSSL_SLHDSA_CONFIG is missing from the dependency cache key, undocumented in --help, and contradicted by INTEGRATION_GUIDE — scripts/utils-wolfssl.sh:64-70
• [Medium] Example build gating and portability: executableDir may trip -Wmaybe-uninitialized, and BUILD_PQC_EXAMPLE is true for verify-only SLH-DSA builds where the example always fails — examples/openssl_example.c:62-75; examples/pqc_openssl_example.c:225-238
• [Low] wp_mlkem_kem.c doc comment no longer matches the code it documents — src/wp_mlkem_kem.c:186

Skipped findings

• [High] libacvp PQC job likely cannot build runtest, so the whole workflow may no-op
• [Medium] SLH-DSA test coverage gaps: four guard paths and the deterministic-keygen seed length validation are unexercised
• [Low] CI workflow hygiene: example steps run before the dependency push, nginx-pqc adds per-workflow apt installs, and test.sh defaults WOLFPROV_ROOT to a path nothing produces
• [Low] wp_slhdsa_key_types uses opaque index arithmetic into a flat parameter array
• [Low] test_slhdsa.c hygiene: randomised input described as deterministic, a verify context initialised with sign-only params, mixed XMEM*/libc string calls, and redundant double cleanup
• [Low] SLH-DSA locking contract is looser than the mutex implies: the key mutex is held across the full multi-second sign and across thread-local CheckKey work, wp_slhdsa_get_key() hands out a raw pointer to guarded state, and construction-time hasPub/hasPriv writes are unlocked
• [Info] settings.h pulls a wolfSSL algorithm header into every translation unit

Review generated by Skoll via Claude/Codex