cose_sign.h

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// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the Apache 2.0 License.
#pragma once
 
#include "crypto/openssl/key_pair.h"
 
#include <openssl/ossl_typ.h>
#include <span>
#include <string>
#include <t_cose/t_cose_sign1_sign.h>
#include <unordered_map>
 
namespace ccf::crypto
{
  // 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: verifiable data structure
  static constexpr int64_t COSE_PHEADER_KEY_VDS = 395;
  // CCF-specific: last signed TxID
  static constexpr const char* COSE_PHEADER_KEY_TXID = "ccf.txid";
 
  class COSEParametersFactory
  {
  public:
    template <typename Callable>
    COSEParametersFactory(Callable&& impl, size_t args_size) :
      impl(std::forward<Callable>(impl)),
      args_size{args_size}
    {}
 
    void apply(QCBOREncodeContext* ctx) const
    {
      impl(ctx);
    }
 
    size_t estimated_size() const
    {
      return args_size;
    }
 
  private:
    std::function<void(QCBOREncodeContext*)> impl{};
    size_t args_size{};
  };
 
  COSEParametersFactory cose_params_int_int(int64_t key, int64_t value);
 
  COSEParametersFactory cose_params_int_string(
    int64_t key, const std::string& value);
 
  COSEParametersFactory cose_params_string_int(
    const std::string& key, int64_t value);
 
  COSEParametersFactory cose_params_string_string(
    const std::string& key, const std::string& value);
 
  COSEParametersFactory cose_params_int_bytes(
    int64_t key, const std::vector<uint8_t>& value);
 
  struct COSESignError : public std::runtime_error
  {
    COSESignError(const std::string& msg) : std::runtime_error(msg) {}
  };
 
  std::optional<int> key_to_cose_alg_id(ccf::crypto::PublicKey_OpenSSL& key);
 
  /* Sign a cose_sign1 payload with custom protected headers as strings, where
       - key: integer label to be assigned in a COSE value
       - value: string behind the label.
 
    Labels have to be unique. For standardised labels list check
    https://www.iana.org/assignments/cose/cose.xhtml#header-parameters.
   */
  std::vector<uint8_t> cose_sign1(
    KeyPair_OpenSSL& key,
    const std::vector<COSEParametersFactory>& protected_headers,
    std::span<const uint8_t> payload);
}