COSE receipts: CPP API

CHANGELOG.md

@@ -21,6 +21,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Added
 
+- Provided API for getting COSE signatures and Merkle proofs (#6477).
+  - Exposed COSE signature in historical API via `TxReceiptImpl`.
+  - Introduced `ccf::describe_merkle_proof_v1(receipt)` for Merkle proof construction in CBOR format.
 - Added COSE signatures over the Merkle root to the KV (#6449).
   - Signing is done with service key (different from raw signatures, which remain unchanged and are still signed by the node key).
   - New signature reside in `public:ccf.internal.cose_signatures`.

CMakeLists.txt

@@ -826,6 +826,7 @@ if(BUILD_TESTS)
     )
     target_link_libraries(
       historical_queries_test PRIVATE http_parser.host sss.host ccf_kv.host
+                                      ccf_endpoints.host
     )
     # Temporarily disabled flaky test
     # https://github.com/microsoft/CCF/issues/4403 add_unit_test( indexing_test

include/ccf/receipt.h

@@ -137,6 +137,16 @@ namespace ccf
   nlohmann::json describe_receipt_v1(const TxReceiptImpl& receipt);
   ReceiptPtr describe_receipt_v2(const TxReceiptImpl& receipt);
 
+  enum MerkleProofLabel : int64_t
+  {
+    // Values TBD:
+    // https://github.com/ietf-scitt/draft-birkholz-cose-cometre-ccf-profile
+    MERKLE_PROOF_LEAF_LABEL = 404,
+    MERKLE_PROOF_PATH_LABEL = 405
+  };
+  std::optional<std::vector<uint8_t>> describe_merkle_proof_v1(
+    const TxReceiptImpl& in);
+
   // Manual JSON serializers are specified for these types as they are not
   // trivial POD structs
 

src/crypto/openssl/cose_sign.cpp

@@ -69,9 +69,6 @@ namespace
     QCBOREncodeContext* cbor_encode,
     const std::vector<ccf::crypto::COSEParametersFactory>& protected_headers)
   {
-    QCBOREncode_AddTag(cbor_encode, CBOR_TAG_COSE_SIGN1);
-    QCBOREncode_OpenArray(cbor_encode);
-
     encode_protected_headers(me, cbor_encode, protected_headers);
 
     QCBOREncode_OpenMap(cbor_encode);
@@ -164,7 +161,8 @@ namespace ccf::crypto
     std::span<const uint8_t> payload)
   {
     const auto buf_size = estimate_buffer_size(protected_headers, payload);
-    Q_USEFUL_BUF_MAKE_STACK_UB(signed_cose_buffer, buf_size);
+    std::vector<uint8_t> underlying_buffer(buf_size);
+    q_useful_buf signed_cose_buffer{underlying_buffer.data(), buf_size};
 
     QCBOREncodeContext cbor_encode;
     QCBOREncode_Init(&cbor_encode, signed_cose_buffer);
@@ -185,6 +183,9 @@ namespace ccf::crypto
 
     t_cose_sign1_set_signing_key(&sign_ctx, signing_key, NULL_Q_USEFUL_BUF_C);
 
+    QCBOREncode_AddTag(&cbor_encode, CBOR_TAG_COSE_SIGN1);
+    QCBOREncode_OpenArray(&cbor_encode);
+
     encode_parameters_custom(&sign_ctx, &cbor_encode, protected_headers);
 
     // Mark empty payload manually.
@@ -216,8 +217,12 @@ namespace ccf::crypto
         fmt::format("Can't finish QCBOR encoding with error code {}", err));
     }
 
-    return {
-      static_cast<const uint8_t*>(signed_cose.ptr),
-      static_cast<const uint8_t*>(signed_cose.ptr) + signed_cose.len};
+    // Memory address is said to match:
+    // github.com/laurencelundblade/QCBOR/blob/v1.4.1/inc/qcbor/qcbor_encode.h#L2190-L2191
+    assert(signed_cose.ptr == underlying_buffer.data());
+
+    underlying_buffer.resize(signed_cose.len);
+    underlying_buffer.shrink_to_fit();
+    return underlying_buffer;
   }
 }

src/node/historical_queries.h

@@ -74,6 +74,14 @@ namespace ccf::historical
     return signatures->get();
   }
 
+  static std::optional<ccf::CoseSignature> get_cose_signature(
+    const ccf::kv::StorePtr& sig_store)
+  {
+    auto tx = sig_store->create_read_only_tx();
+    auto signatures = tx.ro<ccf::CoseSignatures>(ccf::Tables::COSE_SIGNATURES);
+    return signatures->get();
+  }
+
   static std::optional<std::vector<uint8_t>> get_tree(
     const ccf::kv::StorePtr& sig_store)
   {
@@ -430,6 +438,7 @@ namespace ccf::historical
         // Iterate through earlier indices. If this signature covers them
         // then create a receipt for them
         const auto sig = get_signature(sig_details->store);
+        const auto cose_sig = get_cose_signature(sig_details->store);
         ccf::MerkleTreeHistory tree(get_tree(sig_details->store).value());
 
         // This is either pointing at the sig itself, or the closest larger
@@ -453,6 +462,7 @@ namespace ccf::historical
                 details->transaction_id = {sig->view, seqno};
                 details->receipt = std::make_shared<TxReceiptImpl>(
                   sig->sig,
+                  cose_sig,
                   proof.get_root(),
                   proof.get_path(),
                   sig->node,
@@ -735,10 +745,11 @@ namespace ccf::historical
         // the receipt _later_ for an already-fetched signature
         // transaction.
         const auto sig = get_signature(details->store);
+        const auto cose_sig = get_cose_signature(details->store);
         assert(sig.has_value());
         details->transaction_id = {sig->view, sig->seqno};
         details->receipt = std::make_shared<TxReceiptImpl>(
-          sig->sig, sig->root.h, nullptr, sig->node, sig->cert);
+          sig->sig, cose_sig, sig->root.h, nullptr, sig->node, sig->cert);
       }
 
       auto request_it = requests.begin();

src/node/historical_queries_adapter.cpp

@@ -10,6 +10,51 @@
 #include "node/rpc/network_identity_subsystem.h"
 #include "node/tx_receipt_impl.h"
 
+#include <t_cose/t_cose_sign1_sign.h>
+
+namespace
+{
+  void encode_leaf_cbor(
+    QCBOREncodeContext& ctx, const ccf::TxReceiptImpl& receipt)
+  {
+    QCBOREncode_OpenArrayInMapN(
+      &ctx, ccf::MerkleProofLabel::MERKLE_PROOF_LEAF_LABEL);
+
+    // 1 WSD
+    const auto& wsd = receipt.write_set_digest->h;
+    QCBOREncode_AddBytes(&ctx, {wsd.data(), wsd.size()});
+
+    // 2. CE
+    const auto& ce = receipt.commit_evidence.value();
+    QCBOREncode_AddSZString(&ctx, ce.data());
+
+    // 3. CD
+    const auto& cd = receipt.claims_digest.value().h;
+    QCBOREncode_AddBytes(&ctx, {cd.data(), cd.size()});
+
+    QCBOREncode_CloseArray(&ctx);
+  }
+
+  void encode_path_cbor(
+    QCBOREncodeContext& ctx, const ccf::HistoryTree::Path& path)
+  {
+    QCBOREncode_OpenArrayInMapN(
+      &ctx, ccf::MerkleProofLabel::MERKLE_PROOF_PATH_LABEL);
+    for (const auto& node : path)
+    {
+      const int64_t dir =
+        (node.direction == ccf::HistoryTree::Path::Direction::PATH_LEFT);
+      std::vector<uint8_t> hash{node.hash};
+
+      QCBOREncode_OpenArray(&ctx);
+      QCBOREncode_AddInt64(&ctx, dir);
+      QCBOREncode_AddBytes(&ctx, {hash.data(), hash.size()});
+      QCBOREncode_CloseArray(&ctx);
+    }
+    QCBOREncode_CloseArray(&ctx);
+  }
+}
+
 namespace ccf
 {
   nlohmann::json describe_receipt_v1(const TxReceiptImpl& receipt)
@@ -153,6 +198,58 @@ namespace ccf
 
     return receipt;
   }
+
+  std::optional<std::vector<uint8_t>> describe_merkle_proof_v1(
+    const TxReceiptImpl& receipt)
+  {
+    constexpr size_t buf_size = 2048;
+    std::vector<uint8_t> underlying_buffer(buf_size);
+    q_useful_buf buffer{underlying_buffer.data(), buf_size};
+
+    QCBOREncodeContext ctx;
+    QCBOREncode_Init(&ctx, buffer);
+
+    QCBOREncode_BstrWrap(&ctx);
+    QCBOREncode_OpenMap(&ctx);
+
+    if (!receipt.commit_evidence)
+    {
+      LOG_DEBUG_FMT("Merkle proof is missing commit evidence");
+      return std::nullopt;
+    }
+    if (!receipt.write_set_digest)
+    {
+      LOG_DEBUG_FMT("Merkle proof is missing write set digest");
+      return std::nullopt;
+    }
+    encode_leaf_cbor(ctx, receipt);
+
+    if (!receipt.path)
+    {
+      LOG_DEBUG_FMT("Merkle proof is missing path");
+      return std::nullopt;
+    }
+    encode_path_cbor(ctx, *receipt.path);
+
+    QCBOREncode_CloseMap(&ctx);
+    QCBOREncode_CloseBstrWrap2(&ctx, false, nullptr);
+
+    struct q_useful_buf_c result;
+    auto qerr = QCBOREncode_Finish(&ctx, &result);
+    if (qerr)
+    {
+      LOG_DEBUG_FMT("Failed to encode merkle proof: {}", qerr);
+      return std::nullopt;
+    }
+
+    // Memory address is said to match:
+    // github.com/laurencelundblade/QCBOR/blob/v1.4.1/inc/qcbor/qcbor_encode.h#L2190-L2191
+    assert(result.ptr == underlying_buffer.data());
+
+    underlying_buffer.resize(result.len);
+    underlying_buffer.shrink_to_fit();
+    return underlying_buffer;
+  }
 }
 
 namespace ccf::historical

src/node/snapshot_serdes.h

@@ -161,6 +161,7 @@ namespace ccf
     cd.set(std::move(claims_digest));
     ccf::TxReceiptImpl tx_receipt(
       sig,
+      std::nullopt, // cose
       proof.get_root(),
       proof.get_path(),
       node_id,