Consolidate COSE header keys (#7619)

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: maxtropets

src/crypto/cbor.h

@@ -16,6 +16,12 @@
 
 namespace ccf::cbor
 {
+  namespace tag
+  {
+    // https://www.rfc-editor.org/rfc/rfc8152.html#section-2
+    static constexpr int64_t COSE_SIGN_1 = 18;
+  }
+
   struct ValueImpl;
   using Value = std::shared_ptr<ValueImpl>;
 

src/crypto/cose.cpp

@@ -4,6 +4,7 @@
 #include "ccf/crypto/cose.h"
 
 #include "crypto/cbor.h"
+#include "crypto/cose.h"
 
 #include <stdexcept>
 #include <vector>
@@ -19,7 +20,7 @@ namespace ccf::cose::edit
       [&]() { return parse(cose_input); }, "Failed to parse COSE_Sign1");
 
     const auto& cose_envelope = rethrow_with_msg(
-      [&]() -> auto& { return cose_cbor->tag_at(18); },
+      [&]() -> auto& { return cose_cbor->tag_at(ccf::cbor::tag::COSE_SIGN_1); },
       "Failed to parse COSE_Sign1 tag");
 
     const auto& phdr = rethrow_with_msg(
@@ -76,7 +77,8 @@ namespace ccf::cose::edit
     edited.push_back(payload);
     edited.push_back(signature);
 
-    auto edited_envelope = make_tagged(18, make_array(std::move(edited)));
+    auto edited_envelope =
+      make_tagged(ccf::cbor::tag::COSE_SIGN_1, make_array(std::move(edited)));
     return serialize(edited_envelope);
   }
 }

src/crypto/cose.h

@@ -0,0 +1,73 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the Apache 2.0 License.
+
+#pragma once
+
+#include <cstdint>
+#include <string>
+
+namespace ccf
+{
+  namespace cose
+  {
+    namespace header
+    {
+      namespace iana // https://www.iana.org/assignments/cose/cose.xhtml
+      {
+        static constexpr int64_t ALG = 1;
+        static constexpr int64_t CONTENT_TYPE = 3;
+        static constexpr int64_t KID = 4;
+        static constexpr int64_t CWT_CLAIMS = 15;
+        static constexpr int64_t X5CHAIN = 33;
+        static constexpr int64_t PREIMAGE_CONTENT_TYPE = 259;
+        static constexpr int64_t VDS = 395;
+        static constexpr int64_t VDP = 396;
+
+        // https://www.ietf.org/archive/id/draft-ietf-cose-merkle-tree-proofs-18.html#name-cose-header-parameter
+        static constexpr int64_t INCLUSION_PROOFS = -1;
+      }
+      namespace custom
+      {
+        static constexpr std::string_view CCF_V1 = "ccf.v1";
+        static constexpr std::string_view TX_ID = "txid";
+        static constexpr std::string_view TX_RANGE_BEGIN = "epoch.start.txid";
+        static constexpr std::string_view TX_RANGE_END = "epoch.end.txid";
+        static constexpr std::string_view EPOCH_LAST_MERKLE_ROOT =
+          "epoch.end.merkle.root";
+      }
+    }
+    namespace value
+    {
+      // https://www.ietf.org/archive/id/draft-birkholz-cose-receipts-ccf-profile-05.html#section-2
+      static constexpr int64_t CCF_LEDGER_SHA256 = 2;
+
+      static constexpr std::string_view CT_JSON = "application/json";
+      static constexpr std::string_view CT_OCTET_STREAM =
+        "application/octet-stream";
+    }
+  }
+  namespace cwt::header
+  {
+    namespace iana // https://www.iana.org/assignments/cwt/cwt.xhtml
+    {
+      static constexpr int64_t ISS = 1;
+      static constexpr int64_t SUB = 2;
+
+      /* Value is **PLAIN INTEGER**, as per
+       * https://www.rfc-editor.org/rfc/rfc8392#section-2. Quote:
+       *
+       * The "NumericDate" term in this specification has the same meaning and
+       * processing rules as the JWT "NumericDate" term defined in Section 2 of
+       * [RFC7519], except that it is represented as a CBOR numericdate (from
+       * Section 2.4.1 of [RFC7049]) instead of a JSON number. The encoding is
+       * modified so that the leading tag 1 (epoch-based date/time) MUST be
+       * omitted.
+       */
+      static constexpr int64_t IAT = 6;
+    }
+    namespace custom
+    {
+      static constexpr std::string_view SVN = "svn";
+    }
+  }
+}

src/crypto/openssl/cose_sign.cpp

@@ -4,6 +4,7 @@
 #include "crypto/openssl/cose_sign.h"
 
 #include "crypto/cbor.h"
+#include "crypto/cose.h"
 #include "ds/internal_logger.h"
 
 #include <openssl/evp.h>
@@ -38,7 +39,7 @@ namespace
     try
     {
       std::ignore = protected_headers->map_at(
-        ccf::cbor::make_signed(ccf::crypto::COSE_PHEADER_KEY_ALG));
+        ccf::cbor::make_signed(ccf::cose::header::iana::ALG));
     }
     catch (const CBORDecodeError& err)
     {
@@ -62,8 +63,7 @@ namespace
     auto& items = std::get<Map>(protected_headers->value).items;
     items.insert(
       items.begin(),
-      {make_signed(ccf::crypto::COSE_PHEADER_KEY_ALG),
-       make_signed(algorithm_id)});
+      {make_signed(ccf::cose::header::iana::ALG), make_signed(algorithm_id)});
 
     EVP_PKEY* evp_key = key;
     t_cose_key signing_key = {};
@@ -186,7 +186,8 @@ namespace ccf::crypto
     }
     cose_array.push_back(make_bytes(signature));
 
-    auto envelope = make_tagged(18, make_array(std::move(cose_array)));
+    auto envelope = make_tagged(
+      ccf::cbor::tag::COSE_SIGN_1, make_array(std::move(cose_array)));
     try
     {
       return serialize(envelope);

src/crypto/openssl/cose_sign.h

@@ -10,54 +10,6 @@
 
 namespace ccf::crypto
 {
-  // Standardised field: COSE tag.
-  static constexpr int64_t COSE_TAG = 18;
-  // Standardised field: algorithm used to sign.
-  static constexpr int64_t COSE_PHEADER_KEY_ALG = 1;
-  // Standardised: hash of the signing key.
-  static constexpr int64_t COSE_PHEADER_KEY_ID = 4;
-  // Standardised: CWT claims map.
-  static constexpr int64_t COSE_PHEADER_KEY_CWT = 15;
-  // Standardised: verifiable data structure.
-  // https://www.ietf.org/archive/id/draft-ietf-cose-merkle-tree-proofs-18.html#name-cose-header-parameter
-  static constexpr int64_t COSE_PHEADER_KEY_VDS = 395;
-  static constexpr int64_t COSE_PHEADER_VDS_CCF_LEDGER_SHA256 = 2;
-  // Standardised: issued at CWT claim. Value is **PLAIN INTEGER**, as per
-  // https://www.rfc-editor.org/rfc/rfc8392#section-2. Quote:
-  /* The "NumericDate" term in this specification has the same meaning and
-   * processing rules as the JWT "NumericDate" term defined in Section 2 of
-   * [RFC7519], except that it is represented as a CBOR numericdate (from
-   * Section 2.4.1 of [RFC7049]) instead of a JSON number.  The  encoding is
-   * modified so that the leading tag 1 (epoch-based date/time) MUST  be
-   * omitted.
-   */
-  static constexpr int64_t COSE_PHEADER_KEY_IAT = 6;
-  // Standardised: issuer CWT claim.
-  // https://www.iana.org/assignments/cose/cose.xhtml#header-parameters
-  /* The "iss" (issuer) claim identifies the principal that issued the CWT.
-   * The "iss" value is a case-sensitive string containing a StringOrURI value.
-   */
-  static constexpr int64_t COSE_PHEADER_KEY_ISS = 1;
-  // Standardised: subject CWT claim.
-  // https://www.iana.org/assignments/cose/cose.xhtml#header-parameters
-  /* The "sub" (subject) claim identifies the principal that is the subject of
-   * the CWT.  The claims in a CWT are normally statements about the subject.
-   * The "sub" value is a case-sensitive string containing a StringOrURI value.
-   */
-  static constexpr int64_t COSE_PHEADER_KEY_SUB = 2;
-  // CCF headers nested map key.
-  static const std::string COSE_PHEADER_KEY_CCF = "ccf.v1";
-  // CCF-specific: last signed TxID.
-  static const std::string COSE_PHEADER_KEY_TXID = "txid";
-  // CCF-specific: first TX in the range.
-  static const std::string COSE_PHEADER_KEY_RANGE_BEGIN = "epoch.start.txid";
-  // CCF-specific: last TX included in the range.
-  static const std::string COSE_PHEADER_KEY_RANGE_END = "epoch.end.txid";
-  // CCF-specific: last signed Merkle root hash in the range.
-  static const std::string COSE_PHEADER_KEY_EPOCH_LAST_MERKLE_ROOT =
-    "epoch.end.merkle.root";
-  static const std::string COSE_PHEADER_UVM_SVN = "svn";
-
   struct COSESignError : public std::runtime_error
   {
     COSESignError(const std::string& msg) : std::runtime_error(msg) {}

src/crypto/openssl/cose_verifier.cpp

@@ -11,6 +11,7 @@
 #include "x509_time.h"
 
 #include <crypto/cbor.h>
+#include <crypto/cose.h>
 #include <openssl/evp.h>
 #include <openssl/ossl_typ.h>
 #include <openssl/x509.h>
@@ -28,7 +29,8 @@ namespace
       rethrow_with_msg([&]() { return parse(cose_msg); }, "Parse COSE CBOR");
 
     const auto& cose_envelope = rethrow_with_msg(
-      [&]() -> auto& { return cose_cbor->tag_at(18); }, "Parse COSE tag");
+      [&]() -> auto& { return cose_cbor->tag_at(ccf::cbor::tag::COSE_SIGN_1); },
+      "Parse COSE tag");
 
     const auto& phdr_raw = rethrow_with_msg(
       [&]() -> auto& { return cose_envelope->array_at(0); },
@@ -39,7 +41,7 @@ namespace
 
     const int64_t alg = rethrow_with_msg(
       [&]() {
-        return phdr->map_at(make_signed(ccf::crypto::COSE_PHEADER_KEY_ALG))
+        return phdr->map_at(make_signed(ccf::cose::header::iana::ALG))
           ->as_signed();
       },
       "Retrieve alg from protected header");
@@ -206,7 +208,8 @@ namespace ccf::crypto
       rethrow_with_msg([&]() { return parse(cose_msg); }, "Parse COSE CBOR");
 
     const auto& cose_envelope = rethrow_with_msg(
-      [&]() -> auto& { return cose_cbor->tag_at(18); }, "Parse COSE tag");
+      [&]() -> auto& { return cose_cbor->tag_at(ccf::cbor::tag::COSE_SIGN_1); },
+      "Parse COSE tag");
 
     const auto& phdr_raw = rethrow_with_msg(
       [&]() -> auto& { return cose_envelope->array_at(0); },
@@ -217,20 +220,22 @@ namespace ccf::crypto
 
     const auto& ccf_claims = rethrow_with_msg(
       [&]() -> auto& {
-        return phdr->map_at(make_string(ccf::crypto::COSE_PHEADER_KEY_CCF));
+        return phdr->map_at(make_string(ccf::cose::header::custom::CCF_V1));
       },
       "Retrieve CCF claims");
 
     auto from = rethrow_with_msg(
       [&]() {
-        return ccf_claims->map_at(make_string(COSE_PHEADER_KEY_RANGE_BEGIN))
+        return ccf_claims
+          ->map_at(make_string(ccf::cose::header::custom::TX_RANGE_BEGIN))
           ->as_string();
       },
       "Retrieve epoch range begin");
 
     auto to = rethrow_with_msg(
       [&]() {
-        return ccf_claims->map_at(make_string(COSE_PHEADER_KEY_RANGE_END))
+        return ccf_claims
+          ->map_at(make_string(ccf::cose::header::custom::TX_RANGE_END))
           ->as_string();
       },
       "Retrieve epoch range end");

src/crypto/test/cose.cpp

@@ -177,7 +177,8 @@ TEST_CASE("Check unprotected header")
         auto csp_set = ccf::cose::edit::set_unprotected_header(csp, desc);
 
         auto edited = parse(csp_set);
-        const auto& uhdr = edited->tag_at(18)->array_at(1);
+        const auto& uhdr =
+          edited->tag_at(ccf::cbor::tag::COSE_SIGN_1)->array_at(1);
 
         std::vector<MapItem> ref;
         if (std::holds_alternative<ccf::cose::edit::pos::InArray>(position))
@@ -207,7 +208,8 @@ TEST_CASE("Check unprotected header")
         csp, ccf::cose::edit::desc::Empty{});
 
       auto edited = parse(csp_set_empty);
-      const auto& uhdr = edited->tag_at(18)->array_at(1);
+      const auto& uhdr =
+        edited->tag_at(ccf::cbor::tag::COSE_SIGN_1)->array_at(1);
 
       auto ref_map = make_map({});
 

src/crypto/test/crypto.cpp

@@ -16,6 +16,7 @@
 #include "ccf/ds/x509_time_fmt.h"
 #include "crypto/cbor.h"
 #include "crypto/certs.h"
+#include "crypto/cose.h"
 #include "crypto/csr.h"
 #include "crypto/openssl/cose_sign.h"
 #include "crypto/openssl/cose_verifier.h"
@@ -230,7 +231,7 @@ void require_match_headers(
 {
   auto decoded = ccf::cbor::parse(cose_sign);
 
-  const auto& as_cose = decoded->tag_at(18);
+  const auto& as_cose = decoded->tag_at(ccf::cbor::tag::COSE_SIGN_1);
   const auto& raw_phdr = as_cose->array_at(0)->as_bytes();
 
   auto phdr = ccf::cbor::parse(raw_phdr);

src/endpoints/authentication/cose_auth.cpp

@@ -40,7 +40,10 @@ namespace ccf
         [&]() { return parse(cose_sign1); }, "Parse COSE CBOR");
 
       const auto& cose_envelope = rethrow_with_msg(
-        [&]() -> auto& { return cose_cbor->tag_at(18); }, "Parse COSE tag");
+        [&]() -> auto& {
+          return cose_cbor->tag_at(ccf::cbor::tag::COSE_SIGN_1);
+        },
+        "Parse COSE tag");
 
       const auto& phdr_raw = rethrow_with_msg(
         [&]() -> auto& { return cose_envelope->array_at(0); },
@@ -54,13 +57,13 @@ namespace ccf
 
       parsed.alg = rethrow_with_msg(
         [&]() {
-          return phdr->map_at(make_signed(headers::PARAM_ALG))->as_signed();
+          return phdr->map_at(make_signed(header::iana::ALG))->as_signed();
         },
         "Parse alg in protected header");
 
       parsed.kid = buf_to_string(rethrow_with_msg(
         [&]() {
-          return phdr->map_at(make_signed(headers::PARAM_KID))->as_bytes();
+          return phdr->map_at(make_signed(header::iana::KID))->as_bytes();
         },
         "Parse kid in protected header"));
 
@@ -124,7 +127,10 @@ namespace ccf
         [&]() { return parse(cose_sign1); }, "Parse COSE CBOR");
 
       const auto& cose_envelope = rethrow_with_msg(
-        [&]() -> auto& { return cose_cbor->tag_at(18); }, "Parse COSE tag");
+        [&]() -> auto& {
+          return cose_cbor->tag_at(ccf::cbor::tag::COSE_SIGN_1);
+        },
+        "Parse COSE tag");
 
       const auto& phdr_raw = rethrow_with_msg(
         [&]() -> auto& { return cose_envelope->array_at(0); },
@@ -138,13 +144,13 @@ namespace ccf
 
       parsed.alg = rethrow_with_msg(
         [&]() {
-          return phdr->map_at(make_signed(headers::PARAM_ALG))->as_signed();
+          return phdr->map_at(make_signed(header::iana::ALG))->as_signed();
         },
         "Parse alg in protected header");
 
       parsed.kid = buf_to_string(rethrow_with_msg(
         [&]() {
-          return phdr->map_at(make_signed(headers::PARAM_KID))->as_bytes();
+          return phdr->map_at(make_signed(header::iana::KID))->as_bytes();
         },
         "Parse kid in protected header"));