[crypto] Add Operational Keystore for PSA crypto API

src/crypto/BUILD.gn

@@ -116,7 +116,12 @@ if (chip_crypto == "openssl") {
   import("//build_overrides/mbedtls.gni")
 
   source_set("cryptopal_psa") {
-    sources = [ "CHIPCryptoPALPSA.cpp" ]
+    sources = [
+      "CHIPCryptoPALPSA.cpp",
+      "CHIPCryptoPALPSA.h",
+      "PSAOperationalKeystore.cpp",
+      "PSAOperationalKeystore.h",
+    ]
     public_deps = [ ":public_headers" ]
 
     external_mbedtls = current_os == "zephyr"

src/crypto/CHIPCryptoPAL.h

@@ -471,7 +471,7 @@ class P256Keypair : public P256KeypairBase
     /** Release resources associated with this key pair */
     void Clear();
 
-private:
+protected:
     P256PublicKey mPublicKey;
     mutable P256KeypairContext mKeypair;
     bool mInitialized = false;

src/crypto/CHIPCryptoPALPSA.cpp

@@ -20,7 +20,7 @@
  *      PSA Crypto API based implementation of CHIP crypto primitives
  */
 
-#include "CHIPCryptoPAL.h"
+#include "CHIPCryptoPALPSA.h"
 
 #include <lib/core/CHIPEncoding.h>
 #include <lib/core/CHIPSafeCasts.h>
@@ -500,21 +500,6 @@ mbedtls_ecp_group_id MapECPGroupId(SupportedECPKeyTypes keyType)
     }
 }
 
-struct PsaP256KeypairContext
-{
-    psa_key_id_t key_id;
-};
-
-static inline PsaP256KeypairContext & to_keypair_ctx(P256KeypairContext & context)
-{
-    return *SafePointerCast<PsaP256KeypairContext *>(&context);
-}
-
-static inline const PsaP256KeypairContext & to_const_keypair_ctx(const P256KeypairContext & context)
-{
-    return *SafePointerCast<const PsaP256KeypairContext *>(&context);
-}
-
 CHIP_ERROR P256Keypair::ECDSA_sign_msg(const uint8_t * msg, const size_t msg_length, P256ECDSASignature & out_signature) const
 {
     VerifyOrReturnError(mInitialized, CHIP_ERROR_WELL_UNINITIALIZED);
@@ -523,7 +508,7 @@ CHIP_ERROR P256Keypair::ECDSA_sign_msg(const uint8_t * msg, const size_t msg_len
     CHIP_ERROR error                      = CHIP_NO_ERROR;
     psa_status_t status                   = PSA_SUCCESS;
     size_t outputLen                      = 0;
-    const PsaP256KeypairContext & context = to_const_keypair_ctx(mKeypair);
+    const PSAP256KeypairContext & context = toConstPSAContext(mKeypair);
 
     status = psa_sign_message(context.key_id, PSA_ALG_ECDSA(PSA_ALG_SHA_256), msg, msg_length, out_signature.Bytes(),
                               out_signature.Capacity(), &outputLen);
@@ -600,7 +585,7 @@ CHIP_ERROR P256Keypair::ECDH_derive_secret(const P256PublicKey & remote_public_k
 
     CHIP_ERROR error                      = CHIP_NO_ERROR;
     psa_status_t status                   = PSA_SUCCESS;
-    const PsaP256KeypairContext & context = to_const_keypair_ctx(mKeypair);
+    const PSAP256KeypairContext & context = toConstPSAContext(mKeypair);
     const size_t outputSize               = (out_secret.Length() == 0) ? out_secret.Capacity() : out_secret.Length();
     size_t outputLength;
 
@@ -653,7 +638,7 @@ CHIP_ERROR P256Keypair::Initialize(ECPKeyTarget key_target)
     CHIP_ERROR error                = CHIP_NO_ERROR;
     psa_status_t status             = PSA_SUCCESS;
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    PsaP256KeypairContext & context = to_keypair_ctx(mKeypair);
+    PSAP256KeypairContext & context = toPSAContext(mKeypair);
     size_t publicKeyLength          = 0;
 
     // Type based on ECC with the elliptic curve SECP256r1 -> PSA_ECC_FAMILY_SECP_R1
@@ -695,7 +680,7 @@ CHIP_ERROR P256Keypair::Serialize(P256SerializedKeypair & output) const
 {
     CHIP_ERROR error                      = CHIP_NO_ERROR;
     psa_status_t status                   = PSA_SUCCESS;
-    const PsaP256KeypairContext & context = to_const_keypair_ctx(mKeypair);
+    const PSAP256KeypairContext & context = toConstPSAContext(mKeypair);
     const size_t outputSize               = output.Length() == 0 ? output.Capacity() : output.Length();
     Encoding::BufferWriter bbuf(output, outputSize);
     uint8_t privateKey[kP256_PrivateKey_Length];
@@ -723,7 +708,7 @@ CHIP_ERROR P256Keypair::Deserialize(P256SerializedKeypair & input)
     CHIP_ERROR error                = CHIP_NO_ERROR;
     psa_status_t status             = PSA_SUCCESS;
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    PsaP256KeypairContext & context = to_keypair_ctx(mKeypair);
+    PSAP256KeypairContext & context = toPSAContext(mKeypair);
     Encoding::BufferWriter bbuf(mPublicKey, mPublicKey.Length());
 
     Clear();
@@ -751,7 +736,7 @@ void P256Keypair::Clear()
 {
     if (mInitialized)
     {
-        PsaP256KeypairContext & context = to_keypair_ctx(mKeypair);
+        PSAP256KeypairContext & context = toPSAContext(mKeypair);
         psa_destroy_key(context.key_id);
         memset(&context, 0, sizeof(context));
         mInitialized = false;

src/crypto/CHIPCryptoPALPSA.h

@@ -0,0 +1,81 @@
+/*
+ *
+ *    Copyright (c) 2022 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#pragma once
+
+#include "CHIPCryptoPAL.h"
+#include <lib/core/DataModelTypes.h>
+#include <lib/support/SafePointerCast.h>
+
+#include <psa/crypto.h>
+
+namespace chip {
+namespace Crypto {
+
+/**
+ *  @def CHIP_CONFIG_CRYPTO_PSA_KEY_ID_BASE
+ *
+ *  @brief
+ *    Base for PSA key identifier range used by Matter.
+ *
+ *  Cryptographic keys stored in the PSA Internal Trusted Storage must have
+ *  a user-assigned identifer from the range PSA_KEY_ID_USER_MIN to
+ *  PSA_KEY_ID_USER_MAX. This option allows to override the base used to derive
+ *  key identifiers used by Matter to avoid overlapping with other firmware
+ *  components that also use PSA crypto API. The default value was selected
+ *  not to interfere with OpenThread's default base that is 0x20000.
+ *
+ *  Note that volatile keys like ephemeral keys used for ECDH have identifiers
+ *  auto-assigned by the PSA backend.
+ */
+#ifndef CHIP_CONFIG_CRYPTO_PSA_KEY_ID_BASE
+#define CHIP_CONFIG_CRYPTO_PSA_KEY_ID_BASE 0x30000
+#endif // CHIP_CONFIG_CRYPTO_PSA_KEY_ID_BASE
+
+static_assert(CHIP_CONFIG_CRYPTO_PSA_KEY_ID_BASE >= PSA_KEY_ID_USER_MIN &&
+                  CHIP_CONFIG_CRYPTO_PSA_KEY_ID_BASE <= PSA_KEY_ID_USER_MAX,
+              "PSA key ID base out of allowed range");
+
+enum class KeyIdBase : psa_key_id_t
+{
+    // Define key ID range for Node Operational Certificate private keys
+    Operational = CHIP_CONFIG_CRYPTO_PSA_KEY_ID_BASE
+};
+
+constexpr psa_key_id_t MakeOperationalKeyId(FabricIndex fabricIndex)
+{
+    return to_underlying(KeyIdBase::Operational) + static_cast<psa_key_id_t>(fabricIndex);
+}
+
+struct PSAP256KeypairContext
+{
+    psa_key_id_t key_id;
+};
+
+static inline PSAP256KeypairContext & toPSAContext(P256KeypairContext & context)
+{
+    return *SafePointerCast<PSAP256KeypairContext *>(&context);
+}
+
+static inline const PSAP256KeypairContext & toConstPSAContext(const P256KeypairContext & context)
+{
+    return *SafePointerCast<const PSAP256KeypairContext *>(&context);
+}
+
+} // namespace Crypto
+} // namespace chip