feat(tbor): implement RSA-AES key unwrap (GetUnwrappingKey + UnwrapKey) by vsonims · Pull Request #583 · Azure/azihsm-sdk

Vishal Soni (vsonims) · 2026-07-18T20:09:11Z

Summary

Implements the TBOR key-import pair that lets a host RSA-AES-wrap a
key to a partition and re-import it as a masked (unmask-on-use) blob
— the TBOR analogue of MBOR RsaUnwrap, but re-masking the recovered
key under a scope's masking key instead of vaulting it under a key
handle.

Reordered stack: this now sits below the HMAC keygen+mac PR
(#580), so the RSA/AES/ECC key-import path is independent of the HMAC
command work. As the first general crypto command in the stack, it
also introduces the shared session/masking helpers and the shared
HashAlgo wire enum (relocated into key_props). (Replaces the
auto-merged #581, which was closed as a side effect of the branch
reorder.)

`GetUnwrappingKey` (opcode `0x13`)

Returns the partition's RSA-2048 unwrapping public key in HSM wire
format (n_le(256) ‖ e_le(4)). The private half never leaves the
device; UnwrapKey resolves it internally by the partition's
RSA_UNWRAPPING_KEY_ID property. Materialised lazily (std/emulator PAL)
or generated in the background from partition init (hardware); an absent
key surfaces as PendingKeyGeneration so the host retries. Both CO/CU.

`UnwrapKey` (opcode `0x14`)

Within an open CO/CU session, unwrap a host-supplied
RSA-OAEP(KEK) ‖ AES-KWP(key) blob with the partition unwrapping key and
return the recovered key masked (AEAD-GCM-256) under the requested
scope's masking key. Supports the AES, RSA (plain/CRT), ECC, and HMAC
key classes via the shared azihsm_fw_hsm_key_unwrap /
azihsm_fw_hsm_key_decode crates; the decode crate gains an HMAC path
(host-selected SHA variant → the variable-length VarLenHmacShaN kinds). The re-derived wire public key is returned
for the asymmetric (RSA/ECC) classes; symmetric classes return an empty
pub_key. Persists nothing. Both CO/CU.

Shared helpers introduced here

validate_active_session and resolve_masking_key(scope, sess_id)
(Session → per-session key; Ephemeral/Local/SecurityDomain → scope
vault key).
The HashAlgo wire enum, moved into the shared key_props module (it
selects the OAEP hash here and, in feat(tbor): implement HmacGenerateKey + Hmac (masked-key HMAC crypto) #580, the HMAC SHA variant).

Tests / validation

Emu round-trips: GetUnwrappingKey; UnwrapKey AES (masked, no
pubkey) and HMAC key-class (recovered kind = VarLenHmacSha256). The full
unwrap→MAC round-trip lives in feat(tbor): implement HmacGenerateKey + Hmac (masked-key HMAC crypto) #580, which builds on this command.
Full TBOR emu suite green (114 tests at this layer); clippy clean;
nightly fmt + copyright clean; Uno (thumbv7em) build passes.
Docs: docs/tbor-ddi/commands/{get_unwrapping_key,unwrap_key}.md +
README rows (0x13, 0x14).

Endianness note (host wrap)

GetUnwrappingKey returns the modulus/exponent little-endian, and the
device expects the OAEP ciphertext in wire-LE (it flips to big-endian
internally for OpenSSL). The emu test's host-side wrap reverses the
pubkey components (LE→BE for from_hsm_bytes) and the RSA-OAEP
ciphertext (BE→LE) accordingly.

Copilot

Pull request overview

This PR adds the TBOR RSA‑AES key import command pair (GetUnwrappingKey / UnwrapKey) to allow a host to wrap key material to a partition and re-import it as a masked (unmask-on-use) blob, plus supporting plumbing (shared session/masking helpers, HashAlgo wire enum) and tests/docs. It also updates the SessionEx schedule to use a 32‑byte AES‑GCM masking key (TBOR) while keeping legacy MBOR’s 80‑byte CBC masking key schedule.

Changes:

Introduces TBOR opcodes 0x13 (GetUnwrappingKey) and 0x14 (UnwrapKey) end-to-end: wire types, dispatcher routing, handlers, host wrappers, and docs.
Adds shared TBOR helper(s) for active-session validation and resolving per-scope masking keys; moves/introduces HashAlgo in shared key_props.
Extends key decode to support HMAC key material (32/48/64 B → _HmacSha*) and adds TBOR derive support for “reserve + fill later” for mutable buffer fields.

Reviewed changes

Copilot reviewed 28 out of 28 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
fw/plat/uno/fw/pal/src/session.rs	Updates SessionEx blob sizing/validation to use 32-byte masking key for TBOR.
fw/plat/std/pal/src/session.rs	Updates SessionEx blob sizing and makes session masking-key extraction length-aware (legacy vs SessionEx).
fw/pal/traits/src/lib.rs	Changes `SESSION_MASKING_KEY_LEN` to 32 and clarifies it’s for TBOR SessionEx masking.
fw/core/lib/src/op.rs	Classifies new TBOR opcodes as `InSession` for session-flag validation.
fw/core/lib/src/ddi/tbor/unwrap_key.rs	New TBOR `UnwrapKey` handler: unwrap, decode, scope-mask, and respond (incl. pubkey for RSA/ECC).
fw/core/lib/src/ddi/tbor/session_open_finish.rs	Updates SessionEx schedule documentation to 32-byte AES-GCM masking key.
fw/core/lib/src/ddi/tbor/mod.rs	Adds opcode constants, dispatch routing, active-session validation helper, and masking-key resolver helper.
fw/core/lib/src/ddi/tbor/get_unwrapping_key.rs	New TBOR `GetUnwrappingKey` handler: derives and returns partition RSA unwrapping public key.
fw/core/lib/src/ddi/mod.rs	Adds a shared `hmac_hash` helper at the command level for both codecs.
fw/core/lib/src/ddi/mbor/hmac.rs	Switches to shared `crate::ddi::hmac_hash`.
fw/core/lib/src/ddi/mbor/from_pal.rs	Removes the duplicated MBOR-only `hmac_hash` mapping helper.
fw/core/key-decode/src/lib.rs	Adds HMAC as a decode class and wires it into `decode()`.
fw/core/key-decode/src/hmac.rs	New HMAC decode path (length-based classification).
fw/core/ddi/tbor/types/src/unwrap_key.rs	New TBOR wire schema for `UnwrapKey`.
fw/core/ddi/tbor/types/src/lib.rs	Exposes new TBOR type modules (`get_unwrapping_key`, `unwrap_key`).
fw/core/ddi/tbor/types/src/key_props.rs	Expands key-props to include shared `HashAlgo` wire enum.
fw/core/ddi/tbor/types/src/get_unwrapping_key.rs	New TBOR wire schema for `GetUnwrappingKey`.
fw/core/ddi/tbor/derive/src/schema.rs	Documents semantics of `mutable` fields and the reserve+fill pattern.
fw/core/ddi/tbor/derive/src/codegen_enc.rs	Implements encoder generation for `<field>_reserve(len)` for mutable buffers.
docs/tbor-ddi/README.md	Adds `0x13`/`0x14` to the TBOR command table.
docs/tbor-ddi/commands/unwrap_key.md	New documentation page for `UnwrapKey`.
docs/tbor-ddi/commands/get_unwrapping_key.md	New documentation page for `GetUnwrappingKey`.
ddi/tbor/types/tests/commands/unwrap_key.rs	New emu integration tests for `UnwrapKey` (AES + HMAC).
ddi/tbor/types/tests/commands/mod.rs	Registers new TBOR command tests.
ddi/tbor/types/tests/commands/get_unwrapping_key.rs	New emu integration tests for `GetUnwrappingKey` (length/non-zero/stability).
ddi/tbor/types/src/unwrap_key.rs	New host-side TBOR request/response wrappers for `UnwrapKey`.
ddi/tbor/types/src/lib.rs	Re-exports new host-side command wrappers.
ddi/tbor/types/src/get_unwrapping_key.rs	New host-side TBOR request/response wrappers for `GetUnwrappingKey`.

Vishal Soni (vsonims) · 2026-07-18T21:45:46Z

Update: this PR now also introduces encoder "reserve + fill" support in the TBOR derive. For any #[tbor(mutable)] buffer / sealed_key field, the encoder emits a <field>_reserve(len) setter that reserves the data slot without copying, so a response can be built with reserved slots and filled in place via decode_mut (zero-copy — the TBOR analogue of MBOR's reserve/from_layout). GetUnwrappingKey now uses it: the PAL derives the wire public key straight into the reserved response slot (no scratch buffer, no copy). This infrastructure is reused by the stacked HMAC (#580) and AES key-generate commands.

Copilot

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (3)

fw/core/ddi/tbor/types/src/get_unwrapping_key.rs:9

The rustdoc link for UnwrapKey points to crate::hmac, which is unrelated and breaks navigation for readers of the wire schema docs.

//! `GetUnwrappingKey` is an in-session command that returns the
//! partition's RSA-2048 **unwrapping** public key, which the host uses to
//! RSA-AES key-wrap a payload for [`UnwrapKey`](crate::hmac).  The
//! unwrapping key is a device-provisioned partition-internal key; only its

fw/core/ddi/tbor/types/src/unwrap_key.rs:59

The constants are described as being "pinned" into #[tbor(... max_len = ...)] literals, but there are no compile-time assertions to prevent them from drifting out of sync (a pattern used in other TBOR type schemas).

pub const UNWRAP_PUB_KEY_MAX_LEN: usize = 520;

fw/core/lib/src/ddi/tbor/mod.rs:229

resolve_masking_key uses pal.session_masking_key() for KeyScope::Session, but the Uno PAL currently returns UnsupportedCmd from session_masking_key (fw/plat/uno/fw/pal/src/session.rs:333-335). This makes Session-scoped masking fail on Uno/hardware even though the docs and handler comments indicate it should work for any Active session.

) -> HsmResult<&'p DmaBuf> {
    match scope {
        HsmKeyScope::Session => pal.session_masking_key(io, sess_id),
        _ => {
            let mk_key_id = masking_key_id_for_scope(pal, io, scope)?;
            pal.vault_key(io, mk_key_id)
        }

Add the TBOR Hash command (opcode 0x1B): within an open session, compute a SHA-256 / 384 / 512 digest of a host-supplied message and return it. A pure hashing utility — no key, no scope, no partition state — the TBOR analogue of MBOR ShaDigest. Named generically (Hash rather than ShaDigest) to leave room for future XOF / SHAKE variants. Uses the reserve-then-fill pattern: the response frame is encoded with the digest slot reserved, then the PAL hashes straight into it (natural big-endian output) — no intermediate buffer, no copy. Reuses the shared HashAlgo enum from key_props. Wire schemas (fw + host mirror); dispatch / classifier / op.rs wiring (in-session, session-id cross-checked, default-PSK gated). Emu tests verify device digests byte-for-byte against host-computed SHA (azihsm_crypto) for all three algorithms over short / empty / long messages, plus an unknown-algo reject. Per-command docs added. Based on tbor/unwrap-key (#583) for the shared HashAlgo enum; uses opcode 0x1B to avoid collision with the sibling AES / ECC / RSA crypto branches (0x15..0x1A). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Add the TBOR RsaModExp command (opcode 0x1A): the RSA private-key primitive x = y^d mod n using a caller-held masked RSA private key (imported via UnwrapKey with the RSA / RSA-CRT key class). The device unmasks the key in place (recovering its modulus size and CRT form from the blob's key kind), checks the op's usage attribute (Decrypt -> decrypt, Sign -> sign), computes the modular exponentiation into the reserved response slot, and scrubs the recovered key on every path. The raw primitive underlying RSA decrypt / sign — the host applies and removes any padding. TBOR analogue of MBOR RsaModExp; there is no TBOR RSA key generation, so RSA keys enter only through UnwrapKey. Wire schemas (fw + host mirror) with a 1-byte RsaOp selector; dispatch / classifier / op.rs wiring; a strict from_pal::rsa_key mapping (rejects non-RSA-private kinds as InvalidKeyType). Emu tests cover host-verified RSA sign/decrypt roundtrips for 2K/3K/4K and 4K-CRT through the full UnwrapKey(Rsa) -> RsaModExp path, plus wrong-y-length and wrong-key-class rejects. Per-command docs added. Based on tbor/unwrap-key (#583), which provides the DMA-budget-efficient UnwrapKey that lets RSA-3072/4096 keys be imported within 8 KB. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Add the TBOR Hash command (opcode 0x1B): within an open session, compute a SHA-256 / 384 / 512 digest of a host-supplied message and return it. A pure hashing utility — no key, no scope, no partition state — the TBOR analogue of MBOR ShaDigest. Named generically (Hash rather than ShaDigest) to leave room for future XOF / SHAKE variants. Uses the reserve-then-fill pattern: the response frame is encoded with the digest slot reserved, then the PAL hashes straight into it (natural big-endian output) — no intermediate buffer, no copy. Reuses the shared HashAlgo enum from key_props. Wire schemas (fw + host mirror); dispatch / classifier / op.rs wiring (in-session, session-id cross-checked, default-PSK gated). Emu tests verify device digests byte-for-byte against host-computed SHA (azihsm_crypto) for all three algorithms over short / empty / long messages, plus an unknown-algo reject. Per-command docs added. Based on tbor/unwrap-key (#583) for the shared HashAlgo enum; uses opcode 0x1B to avoid collision with the sibling AES / ECC / RSA crypto branches (0x15..0x1A). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Copilot

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (3)

fw/core/ddi/tbor/types/src/get_unwrapping_key.rs:9

Rustdoc link target is incorrect: crate::hmac doesn’t exist in this module and will produce a broken intra-doc link. This should point to the unwrap_key schema/module.

//! `GetUnwrappingKey` is an in-session command that returns the
//! partition's RSA-2048 **unwrapping** public key, which the host uses to
//! RSA-AES key-wrap a payload for [`UnwrapKey`](crate::hmac).  The
//! unwrapping key is a device-provisioned partition-internal key; only its

fw/core/ddi/tbor/types/src/unwrap_key.rs:59

The max-len constants are described as “pinned” to #[tbor(... max_len = ...)] literals, but there are no const _: () = assert!(...) tripwires to keep them in sync. Other TBOR schemas use these asserts to prevent silent drift (e.g. get_unwrapping_key.rs).

/// Max recovered public-key length (RSA-4096 `n_le(512) ‖ e_le(4)`).
/// Pinned into the `#[tbor(buffer, max_len = 520)]` literal on
/// [`TborUnwrapKeyResp::pub_key`].
pub const UNWRAP_PUB_KEY_MAX_LEN: usize = 520;

fw/core/lib/src/ddi/tbor/mod.rs:239

resolve_masking_key assumes HsmKeyScope::Session can always be satisfied via pal.session_masking_key(...), but on the Uno PAL this method currently returns UnsupportedCmd (see fw/plat/uno/fw/pal/src/session.rs:333-335). This means Session-scoped masking (documented as supported) will fail on hardware unless the Uno PAL implements session_masking_key for SessionEx blobs (32-byte AES-GCM key).

/// Resolve the 32-byte AES-256-GCM masking key material for `scope`,
/// returning a borrow of the on-device key.
///
/// `Session` scope resolves to the per-session masking key
/// ([`HsmSessionManager::session_masking_key`](azihsm_fw_hsm_pal_traits::HsmSessionManager::session_masking_key));
/// every other scope resolves via [`masking_key_id_for_scope`] and reads
/// the vault key.  All scopes yield a 32-byte key suitable for the
/// `key_masking::aead` (AES-GCM-256) masked-key system.
fn resolve_masking_key<'p, P: HsmPal>(
    pal: &'p P,
    io: &impl HsmIo,
    scope: HsmKeyScope,
    sess_id: HsmSessId,
) -> HsmResult<&'p DmaBuf> {
    match scope {
        HsmKeyScope::Session => pal.session_masking_key(io, sess_id),
        _ => {
            let mk_key_id = masking_key_id_for_scope(pal, io, scope)?;
            pal.vault_key(io, mk_key_id)
        }
    }

Add the TBOR RsaModExp command (opcode 0x1A): the RSA private-key primitive x = y^d mod n using a caller-held masked RSA private key (imported via UnwrapKey with the RSA / RSA-CRT key class). The device unmasks the key in place (recovering its modulus size and CRT form from the blob's key kind), checks the op's usage attribute (Decrypt -> decrypt, Sign -> sign), computes the modular exponentiation into the reserved response slot, and scrubs the recovered key on every path. The raw primitive underlying RSA decrypt / sign — the host applies and removes any padding. TBOR analogue of MBOR RsaModExp; there is no TBOR RSA key generation, so RSA keys enter only through UnwrapKey. Wire schemas (fw + host mirror) with a 1-byte RsaOp selector; dispatch / classifier / op.rs wiring; a strict from_pal::rsa_key mapping (rejects non-RSA-private kinds as InvalidKeyType). Emu tests cover host-verified RSA sign/decrypt roundtrips for 2K/3K/4K and 4K-CRT through the full UnwrapKey(Rsa) -> RsaModExp path, plus wrong-y-length and wrong-key-class rejects. Per-command docs added. Based on tbor/unwrap-key (#583), which provides the DMA-budget-efficient UnwrapKey that lets RSA-3072/4096 keys be imported within 8 KB. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Add the TBOR Hash command (opcode 0x1B): within an open session, compute a SHA-256 / 384 / 512 digest of a host-supplied message and return it. A pure hashing utility — no key, no scope, no partition state — the TBOR analogue of MBOR ShaDigest. Named generically (Hash rather than ShaDigest) to leave room for future XOF / SHAKE variants. Uses the reserve-then-fill pattern: the response frame is encoded with the digest slot reserved, then the PAL hashes straight into it (natural big-endian output) — no intermediate buffer, no copy. Reuses the shared HashAlgo enum from key_props. Wire schemas (fw + host mirror); dispatch / classifier / op.rs wiring (in-session, session-id cross-checked, default-PSK gated). Emu tests verify device digests byte-for-byte against host-computed SHA (azihsm_crypto) for all three algorithms over short / empty / long messages, plus an unknown-algo reject. Per-command docs added. Based on tbor/unwrap-key (#583) for the shared HashAlgo enum; uses opcode 0x1B to avoid collision with the sibling AES / ECC / RSA crypto branches (0x15..0x1A). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Copilot

Pull request overview

Copilot reviewed 30 out of 30 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

fw/pal/traits/src/lib.rs:440

The doc for SESSION_MASKING_KEY_LEN says the legacy MBOR Session masking key is “sized by the std-PAL-local SESSION_MASKING_KEY_SIZE”, but the same local constant exists in other PALs too (e.g. Uno). This wording is misleading for implementers/readers trying to locate the legacy sizing constant.

/// Present for both CO and CU SessionEx blobs.  Distinct from the legacy
/// MBOR `Session`-blob masking key (an 80 B `aes32 ‖ hmac48` cbc key,
/// sized by the std-PAL-local `SESSION_MASKING_KEY_SIZE`), which the
/// `key_masking::cbc`-based MBOR masked-key system continues to use.

…ey len) - Rename the `oaep_hash` request field to `oaep_hash_algo` (fw + host wire types, handler, tests, docs) for clarity, per review. - `resolve_masking_key` now validates that a `Session`-scope masking key is exactly SESSION_MASKING_KEY_LEN (32) bytes, rejecting a legacy 80-byte MBOR `Session` blob key with `UnsupportedKeyScope` so a TBOR masked-key command can't accidentally run under a legacy session schedule. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 6cd9bfef-fd58-4ac9-bbb0-eb67febe865d

Copilot

Pull request overview

Copilot reviewed 30 out of 30 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

fw/pal/traits/src/lib.rs:436

SESSION_MASKING_KEY_LEN is updated to 32 bytes for TBOR SessionEx, but the HsmVaultKeyKind::SessionEx documentation still describes the SessionEx blob as carrying masking_key(80) with sizes 120/216 (see fw/pal/traits/src/vault.rs:160-164). Please update that enum doc (and any other related docs) to reflect the new masking_key(32) layout (72/168) so implementers don’t rely on the old sizing.

/// Length in bytes of the per-session `masking_key` for TBOR
/// **SessionEx (CU/CO)** sessions.
///
/// 32 B AES-256-GCM key used by the `key_masking::aead`-based TBOR
/// masked-key system (masked keys are scoped and wrapped under AES-GCM).

Address review feedback (jaygmsft): the handler hardcoded both permissions per key class (e.g. RSA always got sign+decrypt), deviating from the MBOR import path where the caller selects the usage. Add a compact 1-byte `KeyUsage` bitfield to the shared TBOR `key_props` (encrypt/decrypt/sign/verify/derive/wrap/unwrap) and carry it on the `UnwrapKey` request. The handler now derives the recovered key's vault attributes from the requested usage, mirroring the MBOR `key_attrs` policy: sign+verify and encrypt+decrypt are matched pairs, exactly one usage group may be set, and each class restricts the valid group(s) (AES: enc/dec; RSA: sign/verify or enc/dec; ECC: sign/verify or derive; HMAC: sign/verify). Invalid combinations are rejected with InvalidPermissions. Adds host KEY_USAGE_* constants, an emu rejection test, and doc updates. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 6cd9bfef-fd58-4ac9-bbb0-eb67febe865d

Copilot

Pull request overview

Copilot reviewed 30 out of 30 changed files in this pull request and generated no new comments.

Address review feedback: the SessionEx masking key is now 32 B (SESSION_MASKING_KEY_LEN, AES-256-GCM), so the SessionEx blob is 72 B (PlainText/CU) / 168 B (Authenticated/CO), not the old 120/216 B with an 80 B masking key. Update the stale `HsmVaultKeyKind::SessionEx` and `session_promote` doc comments accordingly; the legacy MBOR `Session` blob's 80 B CBC key is called out as distinct. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 6cd9bfef-fd58-4ac9-bbb0-eb67febe865d

Copilot

Pull request overview

Copilot reviewed 31 out of 31 changed files in this pull request and generated 3 comments.

…inal; add ECC unwrap test Address review feedback: - `masking_key_id_for_scope` now remaps `PartPropNotFound` to `UnsupportedKeyScope` for `Ephemeral`/`Local` scopes too (not just `SecurityDomain`), so requesting a scope before its masking key is provisioned surfaces the single documented `UnsupportedKeyScope` instead of leaking `PartPropNotFound`. Docs corrected accordingly (the prior `InvalidArg`-before-`Initialized` claim was inaccurate). - Add an emu `UnwrapKey` round-trip for the ECC (P-256) key class, exercising the PKCS#8 decode + re-derived `x‖y` public-key path. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 6cd9bfef-fd58-4ac9-bbb0-eb67febe865d

Copilot

Pull request overview

Copilot reviewed 31 out of 31 changed files in this pull request and generated no new comments.

Jayant Gandhi (jaygmsft)

Approving with suggestions

Add the TBOR RsaModExp command (opcode 0x1A): the RSA private-key primitive x = y^d mod n using a caller-held masked RSA private key (imported via UnwrapKey with the RSA / RSA-CRT key class). The device unmasks the key in place (recovering its modulus size and CRT form from the blob's key kind), checks the op's usage attribute (Decrypt -> decrypt, Sign -> sign), computes the modular exponentiation into the reserved response slot, and scrubs the recovered key on every path. The raw primitive underlying RSA decrypt / sign — the host applies and removes any padding. TBOR analogue of MBOR RsaModExp; there is no TBOR RSA key generation, so RSA keys enter only through UnwrapKey. Wire schemas (fw + host mirror) with a 1-byte RsaOp selector; dispatch / classifier / op.rs wiring; a strict from_pal::rsa_key mapping (rejects non-RSA-private kinds as InvalidKeyType). Emu tests cover host-verified RSA sign/decrypt roundtrips for 2K/3K/4K and 4K-CRT through the full UnwrapKey(Rsa) -> RsaModExp path, plus wrong-y-length and wrong-key-class rejects. Per-command docs added. Based on tbor/unwrap-key (#583), which provides the DMA-budget-efficient UnwrapKey that lets RSA-3072/4096 keys be imported within 8 KB. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Add the TBOR Hash command (opcode 0x1B): within an open session, compute a SHA-256 / 384 / 512 digest of a host-supplied message and return it. A pure hashing utility — no key, no scope, no partition state — the TBOR analogue of MBOR ShaDigest. Named generically (Hash rather than ShaDigest) to leave room for future XOF / SHAKE variants. Uses the reserve-then-fill pattern: the response frame is encoded with the digest slot reserved, then the PAL hashes straight into it (natural big-endian output) — no intermediate buffer, no copy. Reuses the shared HashAlgo enum from key_props. Wire schemas (fw + host mirror); dispatch / classifier / op.rs wiring (in-session, session-id cross-checked, default-PSK gated). Emu tests verify device digests byte-for-byte against host-computed SHA (azihsm_crypto) for all three algorithms over short / empty / long messages, plus an unknown-algo reject. Per-command docs added. Based on tbor/unwrap-key (#583) for the shared HashAlgo enum; uses opcode 0x1B to avoid collision with the sibling AES / ECC / RSA crypto branches (0x15..0x1A). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Add the TBOR RsaModExp command (opcode 0x1A): the RSA private-key primitive x = y^d mod n using a caller-held masked RSA private key (imported via UnwrapKey with the RSA / RSA-CRT key class). The device unmasks the key in place (recovering its modulus size and CRT form from the blob's key kind), checks the op's usage attribute (Decrypt -> decrypt, Sign -> sign), computes the modular exponentiation into the reserved response slot, and scrubs the recovered key on every path. The raw primitive underlying RSA decrypt / sign — the host applies and removes any padding. TBOR analogue of MBOR RsaModExp; there is no TBOR RSA key generation, so RSA keys enter only through UnwrapKey. Wire schemas (fw + host mirror) with a 1-byte RsaOp selector; dispatch / classifier / op.rs wiring; a strict from_pal::rsa_key mapping (rejects non-RSA-private kinds as InvalidKeyType). Emu tests cover host-verified RSA sign/decrypt roundtrips for 2K/3K/4K and 4K-CRT through the full UnwrapKey(Rsa) -> RsaModExp path, plus wrong-y-length and wrong-key-class rejects. Per-command docs added. Based on tbor/unwrap-key (Azure#583), which provides the DMA-budget-efficient UnwrapKey that lets RSA-3072/4096 keys be imported within 8 KB. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Add the TBOR Hash command (opcode 0x1B): within an open session, compute a SHA-256 / 384 / 512 digest of a host-supplied message and return it. A pure hashing utility — no key, no scope, no partition state — the TBOR analogue of MBOR ShaDigest. Named generically (Hash rather than ShaDigest) to leave room for future XOF / SHAKE variants. Uses the reserve-then-fill pattern: the response frame is encoded with the digest slot reserved, then the PAL hashes straight into it (natural big-endian output) — no intermediate buffer, no copy. Reuses the shared HashAlgo enum from key_props. Wire schemas (fw + host mirror); dispatch / classifier / op.rs wiring (in-session, session-id cross-checked, default-PSK gated). Emu tests verify device digests byte-for-byte against host-computed SHA (azihsm_crypto) for all three algorithms over short / empty / long messages, plus an unknown-algo reject. Per-command docs added. Based on tbor/unwrap-key (#583) for the shared HashAlgo enum; uses opcode 0x1B to avoid collision with the sibling AES / ECC / RSA crypto branches (0x15..0x1A). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Add the TBOR Hash command (opcode 0x1B): within an open session, compute a SHA-256 / 384 / 512 digest of a host-supplied message and return it. A pure hashing utility — no key, no scope, no partition state — the TBOR analogue of MBOR ShaDigest. Named generically (Hash rather than ShaDigest) to leave room for future XOF / SHAKE variants. Uses the reserve-then-fill pattern: the response frame is encoded with the digest slot reserved, then the PAL hashes straight into it (natural big-endian output) — no intermediate buffer, no copy. Reuses the shared HashAlgo enum from key_props. Wire schemas (fw + host mirror); dispatch / classifier / op.rs wiring (in-session, session-id cross-checked, default-PSK gated). Emu tests verify device digests byte-for-byte against host-computed SHA (azihsm_crypto) for all three algorithms over short / empty / long messages, plus an unknown-algo reject. Per-command docs added. Based on tbor/unwrap-key (Azure#583) for the shared HashAlgo enum; uses opcode 0x1B to avoid collision with the sibling AES / ECC / RSA crypto branches (0x15..0x1A). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0b09e50a-a9be-4bae-b347-d42dc775a258

Vishal Soni (vsonims) mentioned this pull request Jul 18, 2026

feat(tbor): implement HmacGenerateKey + Hmac (masked-key HMAC crypto) #580

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Vishal Soni (vsonims) changed the base branch from tbor/shared-hmac-hash to main July 18, 2026 20:13

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refactor(fw): make TBOR CU/CO session masking key 32 B AES-256-GCM #578

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refactor(fw): move hmac_hash to the shared ddi layer #579

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Vishal Soni (vsonims) force-pushed the tbor/unwrap-key branch from c106170 to 0db7106 Compare July 18, 2026 21:35

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Comment thread fw/core/ddi/tbor/types/src/get_unwrapping_key.rs

Comment thread fw/core/ddi/tbor/types/src/unwrap_key.rs

Comment thread fw/core/lib/src/ddi/tbor/mod.rs

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feat(tbor): implement AesGenerateKey + AesEncryptDecrypt (masked-key AES) #584

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feat(tbor): implement ECC keygen, sign, and ECDH derive #585

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feat(tbor): implement RSA mod exp #586

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Comment thread fw/core/ddi/tbor/derive/src/codegen_enc.rs

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Vishal Soni (vsonims) mentioned this pull request Jul 19, 2026

feat(tbor): implement ShaDigest #587

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Vishal Soni (vsonims) mentioned this pull request Jul 19, 2026

feat(tbor): implement Hash #588

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Comment thread fw/core/lib/src/ddi/tbor/unwrap_key.rs

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Comment thread fw/core/key-decode/src/lib.rs

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Comment thread ddi/tbor/types/tests/commands/unwrap_key.rs

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Comment thread ddi/tbor/types/src/unwrap_key.rs

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Comment thread fw/core/lib/src/ddi/tbor/unwrap_key.rs

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Merged via the queue into main with commit 594640a Jul 23, 2026
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Jayant Gandhi (jaygmsft) deleted the tbor/unwrap-key branch August 4, 2026 17:28

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Summary

GetUnwrappingKey (opcode 0x13)

UnwrapKey (opcode 0x14)

Shared helpers introduced here

Tests / validation

Endianness note (host wrap)

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Vishal Soni (vsonims) commented Jul 18, 2026 •

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`GetUnwrappingKey` (opcode `0x13`)

`UnwrapKey` (opcode `0x14`)