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diff --git a/src/lib/crypto/rng.h b/src/lib/crypto/rng.h
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+/*
+ * Copyright (c) 2017-2021, [Ribose Inc](https://www.ribose.com).
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1.  Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *
+ * 2.  Redistributions in binary form must reproduce the above copyright notice,
+ *     this list of conditions and the following disclaimer in the documentation
+ *     and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef RNP_RNG_H_
+#define RNP_RNG_H_
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include "config.h"
+
+#ifdef CRYPTO_BACKEND_BOTAN
+typedef struct botan_rng_struct *botan_rng_t;
+#endif
+
+namespace rnp {
+class RNG {
+  private:
+#ifdef CRYPTO_BACKEND_BOTAN
+    struct botan_rng_struct *botan_rng;
+#endif
+  public:
+    enum Type { DRBG, System };
+    /**
+     * @brief Construct a new RNG object.
+     *        Note: OpenSSL uses own global RNG, so this class is not needed there and left
+     *        only for code-level compatibility.
+     *
+     * @param type indicates which random generator to initialize.
+     *             Possible values for Botan backend:
+     *             - DRBG will initialize HMAC_DRBG, this generator is initialized on-demand
+     *               (when used for the first time)
+     *             - SYSTEM will initialize /dev/(u)random
+     */
+    RNG(Type type = Type::DRBG);
+    ~RNG();
+    /**
+     * @brief Get randoom bytes.
+     *
+     * @param data buffer where data should be stored. Cannot be NULL.
+     * @param len number of bytes required.
+     */
+    void get(uint8_t *data, size_t len);
+#ifdef CRYPTO_BACKEND_BOTAN
+    /**
+     * @brief   Returns internal handle to botan rng. Returned
+     *          handle is always initialized. In case of
+     *          internal error NULL is returned
+     */
+    struct botan_rng_struct *handle();
+#endif
+};
+} // namespace rnp
+
+#endif // RNP_RNG_H_