SE050Sim: enforce applet 7.2 read policy on symmetric key objects

[LinuxJedi]

Motivation

On SE05x applet >= 7.2 hardware, ReadObject on a symmetric key object is refused with SW 0x6986 (command not allowed) unless the policy attached at object creation grants POLICY_OBJ_ALLOW_READ; an object created with no policy attached is not readable. wolfSSL's ECDH offload pre-creates the derive target HMACKey object and reads the shared secret back out of it after the derive, so a port that attaches no read policy fails only on real hardware (ZD 22212) - the simulator accepted the read regardless of policy, and the strict-mode CI could not catch it.

Changes

• New policy module: minimal model of the object policy TLV (sequence of length | authObjectId | AR header entries per se05x_const.h), extracting the union of the AR headers.
• WriteSymmKey with P1=HMAC records the attached TAG_POLICY AR header union on the stored HMACKey object (None when no policy is attached).
• In strict mode (SE050_SIM_STRICT_ECDH=1), ReadObject on an HMACKey object is refused with SW_COMMAND_NOT_ALLOWED (0x6986) unless the recorded policy grants POLICY_OBJ_ALLOW_READ. ReadSize stays unguarded since sss_key_store_get_key sizes its buffer with it.
• The ECDH derive preserves the target object's policy when overwriting its value with the shared secret.
• Lenient mode (default) keeps the old always-readable behavior so hosts that predate the contract keep working.

Validation

• cargo test: 35 lib tests (5 new policy-parser tests, 5 new read-policy tests, 1 new derive-preserves-policy test, existing tests updated) + 14 integration tests pass.
• wolfCrypt-vs-simulator Docker run (Dockerfile.wolfcrypt, SE050_SIM_STRICT_ECDH=1):
  • against the wolfSSL se050_applet72_ecdh branch without the read-policy fix: ECC test fails exactly like the customer's hardware log - APDU Transaction Error: Command not allowed - access denied based on object policy (0x6986) in sss_se05x_key_store_get_key, ecc_test_curve_size 28 failed with -248 (WC_HW_E).
  • against the branch with the read-policy fix (attaches a common policy granting read/write/delete to the derive target): full wolfCrypt suite passes.

Pairs with the wolfSSL-side fix on the se050_applet72_ecdh branch; its CI SIMULATORS_REF pin should be bumped to this PR's head once merged.

[Copilot]

Pull request overview

This PR updates the SE050Sim “strict ECDH” behavior to better match SE05x applet >= 7.2 hardware by tracking object creation policies for HMACKey objects and enforcing the “read allowed” bit on ReadObject in strict mode. This closes a simulator/hardware behavioral gap that prevented CI from catching missing read-policy attachment on ECDH derive targets.

Changes:

• Add a minimal policy TLV parser (policy module) that extracts the union of AR headers from TAG_POLICY entries.
• Record TAG_POLICY-derived AR header union on stored HMACKey objects during WriteSymmKey (P1=HMAC).
• In strict mode, refuse ReadObject for HMACKey unless POLICY_OBJ_ALLOW_READ is granted; preserve the target policy across ECDH derive overwrites.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
SE050Sim/se050-sim/src/policy.rs	New minimal policy-entry parser for extracting AR header union.
SE050Sim/se050-sim/src/object_store/types.rs	Extend SecureObject::HMACKey to persist an optional policy header union.
SE050Sim/se050-sim/src/lib.rs	Export the new policy module.
SE050Sim/se050-sim/src/handlers/object_mgmt.rs	Add strict-mode gating for ReadObject exports of HMACKey based on recorded policy.
SE050Sim/se050-sim/src/handlers/ec.rs	Preserve HMACKey policy when ECDH overwrites the derive target.
SE050Sim/se050-sim/src/handlers/aes.rs	Parse and store TAG_POLICY-derived AR header union on HMACKey writes.
SE050Sim/se050-sim/src/dispatch.rs	Thread strict-mode flag into object reads via strict_ecdh_from_env().

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