Expose the Crypto class (#1102)

Expose the Crypto class with Sha256 and HmacSha256 methods.
These methods are useful for users who need to store and compute and
use hashes.
Adapt to coding style.

Relates-To: OAM-792

Signed-off-by: Mykhailo Kuchma <[email protected]>

Author: mykhailo-kuchma

olp-cpp-sdk-authentication/include/olp/authentication/Crypto.h

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2019-2020 HERE Europe B.V.
+ *
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * License-Filename: LICENSE
+ */
+
+#pragma once
+
+#include <array>
+#include <string>
+#include <vector>
+
+#include <olp/authentication/AuthenticationApi.h>
+
+namespace olp {
+namespace authentication {
+
+/**
+ * @brief Crypto class exposes the cryptographic algoritms used by the library.
+ */
+class AUTHENTICATION_API Crypto {
+ public:
+  static const size_t Sha256DigestLength = 32;
+  using Sha256Digest = std::array<unsigned char, Sha256DigestLength>;
+
+  /**
+   * @brief Sha256 cryptographic function used to compute the hash value for a
+   * buffer.
+   *
+   * @param content A vector of unsigned chars for which the hash is computed.
+   *
+   * @return An array of 32 bytes that represent a hash value.
+   */
+  static Sha256Digest Sha256(const std::vector<unsigned char>& content);
+
+  /**
+   * @brief HMAC function based on SHA-256 hash function.
+   *
+   * @param key A key.
+   * @param message A message.
+   *
+   * @return An array of 32 bytes that represent a hash value.
+   */
+  static Sha256Digest HmacSha256(const std::string& key,
+                                 const std::string& message);
+};
+
+}  // namespace authentication
+}  // namespace olp

olp-cpp-sdk-authentication/src/AuthenticationClientUtils.cpp

@@ -29,7 +29,7 @@
 #include <rapidjson/writer.h>
 
 #include "Constants.h"
-#include "Crypto.h"
+#include <olp/authentication/Crypto.h>
 #include "olp/core/http/NetworkUtils.h"
 #include "olp/core/utils/Base64.h"
 #include "olp/core/utils/Url.h"
@@ -55,8 +55,8 @@ constexpr auto kOauthSignatureMethod = "oauth_signature_method";
 constexpr auto kVersion = "1.0";
 constexpr auto kHmac = "HMAC-SHA256";
 
-std::string Base64Encode(const std::vector<uint8_t>& vector) {
-  std::string ret = olp::utils::Base64Encode(vector);
+std::string Base64Encode(const Crypto::Sha256Digest& digest) {
+  std::string ret = olp::utils::Base64Encode(digest.data(), digest.size());
   // Base64 encode sometimes return multiline with garbage at the end
   if (!ret.empty()) {
     auto loc = ret.find(kLineFeed);
@@ -299,7 +299,7 @@ std::string GenerateAuthorizationHeader(
          << encoded_query;
 
   const std::string encode_key = credentials.GetSecret() + kParamAdd;
-  auto hmac_result = Crypto::hmac_sha256(encode_key, signature_base.str());
+  auto hmac_result = Crypto::HmacSha256(encode_key, signature_base.str());
   auto signature = Base64Encode(hmac_result);
 
   std::stringstream authorization;