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diff --git a/util/crypto/rsa_private_key.h b/util/crypto/rsa_private_key.h
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+++ b/util/crypto/rsa_private_key.h
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+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UTIL_CRYPTO_RSA_PRIVATE_KEY_H_
+#define UTIL_CRYPTO_RSA_PRIVATE_KEY_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <memory>
+#include <vector>
+
+#include "openssl/base.h"
+#include "platform/base/macros.h"
+
+namespace openscreen {
+
+// Encapsulates an RSA private key. Can be used to generate new keys, export
+// keys to other formats, or to extract a public key.
+class RSAPrivateKey {
+ public:
+  ~RSAPrivateKey();
+
+  // Create a new random instance. Can return nullptr if initialization fails.
+  static std::unique_ptr<RSAPrivateKey> Create(uint16_t num_bits);
+
+  // Create a new instance by importing an existing private key. The format is
+  // an ASN.1-encoded PrivateKeyInfo block from PKCS #8. This can return nullptr
+  // if initialization fails.
+  static std::unique_ptr<RSAPrivateKey> CreateFromPrivateKeyInfo(
+      const std::vector<uint8_t>& input);
+
+  // Create a new instance from an existing EVP_PKEY, taking a
+  // reference to it. |key| must be an RSA key. Returns nullptr on
+  // failure.
+  static std::unique_ptr<RSAPrivateKey> CreateFromKey(EVP_PKEY* key);
+
+  EVP_PKEY* key() { return key_.get(); }
+
+  // Creates a copy of the object.
+  std::unique_ptr<RSAPrivateKey> Copy() const;
+
+  // Exports the private key to a PKCS #8 PrivateKeyInfo block.
+  bool ExportPrivateKey(std::vector<uint8_t>* output) const;
+
+  // Exports the public key to an X509 SubjectPublicKeyInfo block.
+  bool ExportPublicKey(std::vector<uint8_t>* output) const;
+
+ private:
+  // Constructor is private. Use one of the Create*() methods above instead.
+  RSAPrivateKey();
+
+  // TODO(jophba): switch to shared pointer to allow copy.
+  bssl::UniquePtr<EVP_PKEY> key_;
+
+  OSP_DISALLOW_COPY_AND_ASSIGN(RSAPrivateKey);
+};
+
+}  // namespace openscreen
+
+#endif  // UTIL_CRYPTO_RSA_PRIVATE_KEY_H_