feat(fw): implement GetUnwrappingKey DDI handler by jaygmsft · Pull Request #501 · Azure/azihsm-sdk

jaygmsft · 2026-06-30T17:45:39Z

Within an open session, return the partition's RSA-2048 unwrapping public key (raw wire n_le || e_le) plus its vault key id, for the host to RSA-AES key-wrap a payload for RsaUnwrap.

Lazy RSA-2048 keygen via a new HsmPartitionManager:: part_ensure_unwrapping_key: the std PAL generates on first use (keygen is too slow to run at partition enable); hardware PALs generate in the background from part-init and report PendingKeyGeneration until ready, prompting the host to retry.
Derive the public key from the vault-stored private key on demand (no separate pub cached, matching the reference firmware) via a new HsmRsa::rsa_priv_pub_key that converts the PAL's vault representation (raw on hardware, DER in the std/OpenSSL PAL) into wire form; the std driver owns the big-endian->little-endian flip.
Serialize the public key straight into the response frame's reserved slot (query/alloc/use) — no intermediate buffer or copy.
Centralize the BE<->LE reverse_copy helper in drivers/mod.rs, shared by the ecc and rsa drivers.
Fix ras_gen_keypair -> rsa_gen_keypair typo.

masked_key is emitted empty for now (firmware-side masking pending the unmask path). Uno PAL methods are stubbed (PendingKeyGeneration / UnsupportedCmd).

Adds get_unwrapping_key smoke tests (happy path, stable-across-calls, no-session). Full smoke 53/53; std PAL unit 157/157.

Within an open session, return the partition's RSA-2048 unwrapping public key (raw wire `n_le || e_le`) plus its vault key id, for the host to RSA-AES key-wrap a payload for RsaUnwrap. - Lazy RSA-2048 keygen via a new HsmPartitionManager:: part_ensure_unwrapping_key: the std PAL generates on first use (keygen is too slow to run at partition enable); hardware PALs generate in the background from part-init and report PendingKeyGeneration until ready, prompting the host to retry. - Derive the public key from the vault-stored private key on demand (no separate pub cached, matching the reference firmware) via a new HsmRsa::rsa_priv_pub_key that converts the PAL's vault representation (raw on hardware, DER in the std/OpenSSL PAL) into wire form; the std driver owns the big-endian->little-endian flip. - Serialize the public key straight into the response frame's reserved slot (query/alloc/use) — no intermediate buffer or copy. - Centralize the BE<->LE reverse_copy helper in drivers/mod.rs, shared by the ecc and rsa drivers. - Fix ras_gen_keypair -> rsa_gen_keypair typo. masked_key is emitted empty for now (firmware-side masking pending the unmask path). Uno PAL methods are stubbed (PendingKeyGeneration / UnsupportedCmd). Adds get_unwrapping_key smoke tests (happy path, stable-across-calls, no-session). Full smoke 53/53; std PAL unit 157/157. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Implements the MBOR GetUnwrappingKey DDI command to return a partition’s RSA-2048 unwrapping public key (wire n_le || e_le) and its vault key id, with PAL support for ensuring/deriving the key and emulator smoke tests.

Changes:

Added core MBOR handler + type plumbing for GetUnwrappingKey and wired it into the dispatcher.
Added PAL APIs to (a) ensure the partition unwrapping key exists and (b) derive a wire-format public key from a vault-stored private key (std PAL implemented; Uno stubs).
Centralized the BE↔LE byte reversal helper and added std RSA public-key wire serialization; added MBOR integration smoke tests.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
fw/plat/uno/fw/pal/src/part.rs	Adds Uno stub for `part_ensure_unwrapping_key` (returns `PendingKeyGeneration`).
fw/plat/uno/fw/pal/src/crypto/rsa.rs	Fixes `ras_gen_keypair` typo to `rsa_gen_keypair`; adds Uno stub for `rsa_priv_pub_key`.
fw/plat/std/pal/src/rsa.rs	Implements `rsa_priv_pub_key` for std PAL by parsing vault DER and emitting wire `n_le
fw/plat/std/pal/src/part.rs	Adds std PAL lazy generation + vault persistence for the unwrapping key id.
fw/plat/std/pal/src/drivers/rsa.rs	Adds `rsa_pub_wire` helper to serialize OpenSSL public key components into wire form.
fw/plat/std/pal/src/drivers/mod.rs	Centralizes `reverse_copy` for BE↔LE component conversion shared across drivers.
fw/plat/std/pal/src/drivers/ecc.rs	Switches ECC driver to use centralized `reverse_copy`.
fw/pal/traits/src/part.rs	Extends `HsmPartitionManager` trait with `part_ensure_unwrapping_key` and docs.
fw/pal/traits/src/crypto/rsa.rs	Renames `ras_gen_keypair` → `rsa_gen_keypair`; adds `rsa_priv_pub_key` to `HsmRsa` trait.
fw/core/lib/src/ddi/mbor/mod.rs	Registers and dispatches the new `GetUnwrappingKey` handler.
fw/core/lib/src/ddi/mbor/get_unwrapping_key.rs	New MBOR command handler that allocates the response and writes pubkey directly into the reserved frame slot.
fw/core/ddi/mbor/types/src/get_unwrapping_key.rs	Marks `pub_key` as a framed field for correct encoding/layout.
ddi/mbor/types/tests/integration/get_unwrapping_key_smoke.rs	Adds integration smoke tests (happy path, stability across calls, and no-session rejection).
ddi/mbor/types/tests/azihsm_ddi_tests.rs	Includes the new smoke test module in the test suite.

- part_ensure_unwrapping_key (std): close a TOCTOU race across the keygen await — re-check unwrapping_key_id while holding the mutable entry borrow before creating the vault key, so two concurrent callers on one partition can't both insert (leaking one) and return different ids. The re-check -> create -> store window is await-free, hence atomic on the single-threaded executor. - rsa_pub_wire (std driver): bound the modulus length against the fixed 512-byte scratch buffer and error out, so a malformed/oversized vault key can never panic across the PAL trust boundary. - Docs: drop the stale PartPropId::RSA_UNWRAPPING_PUB_KEY reference (no such property — the public key is derived on demand, not cached), and reword the unwrapping-key caching as the partition's current enabled incarnation (clear_enabled_state deletes it on disable/free). - Smoke test: drop the `key_id != 0` assertion — key_id is an opaque handle and the sim/mock backend (which CI runs this suite under) legitimately assigns 0; the stability test already covers id consistency. Validation: get_unwrapping_key smoke 3/3 under both mock and emu; full mock smoke 45/45; std unit 157/157; host + Uno build clean. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Address PR feedback: follow the existing property model instead of adding a new PAL trait method for the unwrapping key. - Remove HsmPartitionManager::part_ensure_unwrapping_key. The handler now just reads the partition's RSA_UNWRAPPING_KEY_ID property via part_unwrapping_key_id; an absent id (PartPropNotFound) means generation is still pending, surfaced as PendingKeyGeneration so the host retries. This keeps the core handler PAL-agnostic — real hardware generates the key in the background at part-init and only ever exposes it through the property. - std PAL: provision the key lazily behind the property read. A new private provision_unwrapping_key runs inside part_prop_get_u16 for RSA_UNWRAPPING_KEY_ID, generating the RSA-2048 key synchronously on first read so only a GetUnwrappingKey request pays the keygen cost (never partition enable — avoids a ~19x smoke-test slowdown). The routine is await-free, so on the single-threaded executor it runs atomically: concurrent reads cannot race to generate two keys (first write wins, the rest reuse it). - Uno PAL: drop the part_ensure_unwrapping_key stub; its getter stays uniform with every other key-id property (PartPropNotFound when unset), which the handler maps to PendingKeyGeneration. Validation: get_unwrapping_key smoke 3/3 under both mock and emu; std unit 157/157; host + Uno build clean; fmt/copyright clean. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.

Co-authored-by: jaygmsft <22506014+jaygmsft@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Copilot AI review requested due to automatic review settings June 30, 2026 17:45

Copilot started reviewing on behalf of jaygmsft June 30, 2026 17:46 View session

Copilot AI reviewed Jun 30, 2026

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Comment thread fw/pal/traits/src/part.rs Outdated

Comment thread fw/plat/std/pal/src/part.rs Outdated

Comment thread fw/plat/std/pal/src/drivers/rsa.rs Outdated

Comment thread fw/core/lib/src/ddi/mbor/get_unwrapping_key.rs Outdated

jaygmsft enabled auto-merge June 30, 2026 18:25

vsonims requested changes Jun 30, 2026

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Comment thread fw/pal/traits/src/part.rs Outdated

Copilot AI review requested due to automatic review settings June 30, 2026 23:34

Copilot started reviewing on behalf of jaygmsft June 30, 2026 23:35 View session

jaygmsft requested a review from vsonims June 30, 2026 23:36

Copilot AI reviewed Jun 30, 2026

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Comment thread fw/core/lib/src/ddi/mbor/get_unwrapping_key.rs

Comment thread fw/plat/std/pal/src/drivers/rsa.rs

Comment thread fw/plat/std/pal/src/part.rs Outdated

Comment thread fw/pal/traits/src/crypto/rsa.rs Outdated

vsonims previously approved these changes Jul 1, 2026

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Copilot started work on behalf of jaygmsft July 1, 2026 22:19 View session

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fc3f54b

Co-authored-by: jaygmsft <22506014+jaygmsft@users.noreply.github.com>

Copilot AI dismissed vsonims’s stale review via fc3f54b July 1, 2026 22:26

Copilot finished work on behalf of jaygmsft July 1, 2026 22:26

Merge branch 'main' into user/jayg/get_unwrap_key

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Copilot AI review requested due to automatic review settings July 1, 2026 22:27

Copilot started reviewing on behalf of jaygmsft July 1, 2026 22:27 View session

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Comment thread fw/core/lib/src/ddi/mbor/get_unwrapping_key.rs

Comment thread ddi/mbor/types/tests/integration/get_unwrapping_key_smoke.rs

vsonims approved these changes Jul 1, 2026

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jaygmsft disabled auto-merge July 1, 2026 22:39

jaygmsft enabled auto-merge July 1, 2026 22:51

jaygmsft added this pull request to the merge queue Jul 1, 2026

Merged via the queue into main with commit 9533fe3 Jul 1, 2026
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jaygmsft deleted the user/jayg/get_unwrap_key branch July 1, 2026 23:56

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feat(fw): implement GetUnwrappingKey DDI handler#501

feat(fw): implement GetUnwrappingKey DDI handler#501
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