Roll forward to cl/314747126

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: Ie19e006429b138b3768e97dae971a43fdc5ef8bf

cpp/core_v2/internal/mediums/utils.cc

@@ -0,0 +1,55 @@
+// Copyright 2020 Google LLC
+//
+// 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
+//
+//     https://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.
+
+#include "core_v2/internal/mediums/utils.h"
+
+#include <memory>
+#include <string>
+
+#include "platform_v2/base/prng.h"
+#include "platform_v2/public/crypto.h"
+
+namespace location {
+namespace nearby {
+namespace connections {
+
+ByteArray Utils::GenerateRandomBytes(size_t length) {
+  Prng rng;
+  std::string data;
+  data.reserve(length);
+
+  // Adds 4 random bytes per iteration.
+  while (length > 0) {
+    std::uint32_t val = rng.NextUint32();
+    for (int i = 0; i < 4; i++) {
+      data += val & 0xFF;
+      val >>= 8;
+      length--;
+
+      if (!length) break;
+    }
+  }
+
+  return ByteArray(data);
+}
+
+ByteArray Utils::Sha256Hash(const ByteArray& source, size_t length) {
+  ByteArray full_hash(length);
+  full_hash.CopyAt(0, Crypto::Sha256(std::string(source)));
+  return full_hash;
+}
+
+}  // namespace connections
+}  // namespace nearby
+}  // namespace location