Add support for for SLH-DSA by padelsbach · Pull Request #512 · wolfSSL/wolfHSM

padelsbach · 2026-08-14T19:54:19Z

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wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #512

Scan targets checked: wolfhsm-core-bugs, wolfhsm-crypto-bugs, wolfhsm-src

Findings: 11
11 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Reported findings require changes before merge.

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #512

Scan targets checked: wolfhsm-core-bugs, wolfhsm-crypto-bugs, wolfhsm-src

Findings: 7
7 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Reported findings require changes before merge.

Frauschi

Went through the SLH-DSA callback support. Big addition, and the structure mirrors the ML-DSA paths closely enough to follow easily.

Comments inline. The ones I would most like to see addressed are the DMA READ_POST after a denied READ_PRE in _HandleSlhDsaVerifyDma, the unvalidated seedSz / 3 in both keygen handlers, and the seed left resident in the comm packet. The rest are smaller consistency points against the ML-DSA and ML-KEM siblings, and the last few are nits you can take or leave.

Nothing here is a blocker.

Frauschi

Two small follow-ups from the last round - neither is blocking, and the rest of what I raised looks good now.

Copilot

Copilot review overview

🟡 Changes recommended

Cache-mode flag handling, DER error reporting, and DMA cleanup can currently produce false success or leave unintended cached keys.

Review effort: Balanced
Findings: 3

Open (3)

EPHEMERAL flag discards generated key in cache-only API · New
Explicit key IDs can leave cached keys after DMA failure · New
Zero-length DER serialization reported as successful · New

What changed in this PR

Adds end-to-end SLH-DSA support across wolfHSM, including key management, signing, verification, DMA, crypto callbacks, examples, and CI coverage.

Changes:

Adds SLH-DSA wire protocols and client/server cryptographic operations.
Supports cached, exported, seeded, non-DMA, DMA, and callback-only workflows.
Extends configuration, tests, examples, and CI for SLH-DSA.

File	Description
`wolfhsm/wh_settings.h`	Documents SLH-DSA buffer requirements.
`wolfhsm/wh_server_crypto.h`	Declares server cache helpers.
`wolfhsm/wh_message_crypto.h`	Defines SLH-DSA wire messages.
`wolfhsm/wh_crypto.h`	Declares DER serialization support.
`wolfhsm/wh_common.h`	Adds the SLH-DSA algorithm identifier.
`wolfhsm/wh_client_crypto.h`	Exposes client SLH-DSA APIs.
`test/wh_test_check_struct_padding.c`	Covers new message layouts.
`test/config/user_settings.h`	Enables SLH-DSA in tests.
`test-refactor/wh_test_list.c`	Registers SLH-DSA tests.
`test-refactor/posix/Makefile`	Adds verify-only configuration.
`test-refactor/misc/wh_test_check_struct_padding.c`	Covers refactored message layouts.
`src/wh_server_keystore.c`	Supports public-key export.
`src/wh_server_crypto.c`	Implements server operations and DMA handlers.
`src/wh_message_crypto.c`	Implements message translation.
`src/wh_crypto.c`	Implements SLH-DSA DER conversion.
`src/wh_client_cryptocb.c`	Integrates wolfCrypt callbacks.
`src/wh_client_crypto.c`	Implements client and DMA APIs.
`examples/posix/wh_posix_server/user_settings.h`	Enables server-side SLH-DSA.
`examples/posix/wh_posix_client/user_settings.h`	Enables client and callback-only modes.
`examples/posix/wh_posix_client/Makefile`	Adds callback-only build selection.
`examples/demo/client/wh_demo_client_crypto.h`	Declares the SLH-DSA demo.
`examples/demo/client/wh_demo_client_crypto.c`	Implements the SLH-DSA demo.
`examples/demo/client/wh_demo_client_all.c`	Runs the SLH-DSA demo.
`.github/workflows/build-and-test-refactor.yml`	Tests verify-only builds.
`.github/workflows/build-and-run-examples.yml`	Tests callback-only operation.

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Copilot

Copilot review overview

🟡 Changes recommended

Non-DMA responses expose uninitialized padding, and the server header lacks the required SLH-DSA type include.

Review effort: Balanced
Findings: 2

Open (2)

Uninitialized response padding leaks stack data · New
Missing SLH-DSA header include causes unknown type · New

Resolved since last review (3)

Zero-length DER serialization reported as successful
Explicit key IDs can leave cached keys after DMA failure
EPHEMERAL flag discards generated key in cache-only API

padelsbach · 2026-10-30T01:05:14Z

+    int                                ret;
+    SlhDsaKey                          key[1];
+    whMessageCrypto_SlhDsaSignRequest  req;
+    whMessageCrypto_SlhDsaSignResponse res;


bigbrett · 2026-10-05T20:07:50Z

@padelsbach can you check the copilot comments and address if necessary, otherwise resolve and reassign me plz

…minor cleanup

…lag for cleanup, zero check on cleanup

…to match LMS/XMSS

padelsbach force-pushed the add-crypto-cb-slhdsa branch 2 times, most recently from aed3238 to 7fe4069 Compare August 21, 2026 23:20

padelsbach force-pushed the add-crypto-cb-slhdsa branch 4 times, most recently from 64514ae to a9eb8a9 Compare September 16, 2026 19:16

padelsbach marked this pull request as ready for review September 16, 2026 19:49

padelsbach requested review from Frauschi, bigbrett and wolfSSL-Fenrir-bot and removed request for bigbrett September 16, 2026 19:49

padelsbach force-pushed the add-crypto-cb-slhdsa branch from a9eb8a9 to 43e9f7f Compare September 16, 2026 19:55

wolfSSL-Fenrir-bot requested changes Sep 16, 2026

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padelsbach requested a review from wolfSSL-Fenrir-bot September 16, 2026 21:22

wolfSSL-Fenrir-bot requested changes Sep 16, 2026

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padelsbach requested a review from wolfSSL-Fenrir-bot September 18, 2026 00:56

padelsbach assigned bigbrett Sep 18, 2026

Frauschi reviewed Sep 21, 2026

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Frauschi assigned padelsbach Sep 21, 2026

bigbrett removed their assignment Sep 21, 2026

padelsbach assigned Frauschi Sep 22, 2026

padelsbach requested a review from Frauschi September 22, 2026 03:28

Frauschi reviewed Sep 22, 2026

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Comment thread src/wh_server_crypto.c

Comment thread src/wh_client_crypto.c Outdated

Frauschi removed their assignment Sep 22, 2026

padelsbach assigned Frauschi Sep 22, 2026

Frauschi previously approved these changes Sep 23, 2026

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Frauschi assigned bigbrett and unassigned Frauschi Sep 23, 2026

padelsbach changed the title ~~Add crypto callback mode for SLH-DSA~~ Add support for for SLH-DSA Sep 25, 2026

Copilot AI reviewed Oct 2, 2026

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Comment thread src/wh_client_crypto.c Outdated

Comment thread src/wh_client_crypto.c Outdated

Comment thread src/wh_crypto.c

padelsbach requested review from Frauschi and a balanced review from Copilot October 3, 2026 00:42

Copilot started reviewing on behalf of padelsbach October 3, 2026 00:53

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padelsbach removed their assignment Oct 3, 2026

Copilot AI reviewed Oct 3, 2026

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bigbrett assigned padelsbach and unassigned bigbrett Oct 5, 2026

padelsbach force-pushed the add-crypto-cb-slhdsa branch 2 times, most recently from bbc5a63 to aa14855 Compare October 9, 2026 16:06

padelsbach force-pushed the add-crypto-cb-slhdsa branch from fe43259 to 9efa82f Compare October 13, 2026 04:40

padelsbach added 16 commits October 29, 2026 17:39

Add crypto callback mode for SLH-DSA

3a60654

PR feedback: fixes bare handles, verify-only, and DMA

213d410

PR feedback: fixes DMA write post, sign size, zeroization

c881cd9

PR feedback: address POST error, PRE handling, DMA_PARAM, etc

db1ab38

PR feedback: fix aborted case, POST failure case, zeroization, other …

f20cc23

…minor cleanup

Add verify-only test cases

65d6e41

PR feedback: adjust types, zeroization, etc

77b5f9d

PR feedback: zeroization size, reduce comment block

2900e75

PR feedback: add checks for EPHEMERAL, missing zeroizing, committed f…

7fc3e28

…lag for cleanup, zero check on cleanup

PR feedback: zero 'res' vars before use

81ff637

PR feedback: add missing include

8e5ccbb

SLH-DSA: clean up comments

1b26c52

SLH-DSA: style update of total_len arithmetic

4c586a2

SLH-DSA: apply clang-format

14fc950

Updated handling of large SLH-DSA buffers, add local verify callback …

c1376ca

…to match LMS/XMSS

SLH-DSA: align DMA output buffers, clear verify result on failure

7531b59

padelsbach force-pushed the add-crypto-cb-slhdsa branch from d408125 to 7531b59 Compare October 30, 2026 01:04

padelsbach assigned bigbrett Oct 30, 2026

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padelsbach commented Aug 14, 2026

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Fenrir Automated Review — PR #512

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Fenrir Automated Review — PR #512

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Copilot review overview

🟡 Changes recommended

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Copilot review overview

🟡 Changes recommended

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padelsbach Oct 30, 2026

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bigbrett commented Oct 5, 2026

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