/*

* (C) 2014,2024 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#ifndef BOTAN_X25519_H_

#define BOTAN_X25519_H_

#include <botan/pk_keys.h>

namespace Botan {

class BOTAN_PUBLIC_API(2, 0) X25519_PublicKey : public virtual Public_Key {

   public:

      std::string algo_name() const override { return "X25519"; }

      size_t estimated_strength() const override { return 128; }

      size_t key_length() const override { return 255; }

      bool check_key(RandomNumberGenerator& rng, bool strong) const override;

      AlgorithmIdentifier algorithm_identifier() const override;

      std::vector<uint8_t> raw_public_key_bits() const override;

      std::vector<uint8_t> public_key_bits() const override;

      std::vector<uint8_t> public_value() const { return m_public; }

      bool supports_operation(PublicKeyOperation op) const override { return (op == PublicKeyOperation::KeyAgreement); }

      std::unique_ptr<Private_Key> generate_another(RandomNumberGenerator& rng) const final;

      /**

      * Create a X25519 Public Key.

      * @param alg_id the X.509 algorithm identifier

      * @param key_bits DER encoded public key bits

      */

      X25519_PublicKey(const AlgorithmIdentifier& alg_id, std::span<const uint8_t> key_bits);

      /**

      * Create a X25519 Public Key.

      * @param pub 32-byte raw public key

      */

      explicit X25519_PublicKey(std::span<const uint8_t> pub);

   protected:

      X25519_PublicKey() = default;

      std::vector<uint8_t> m_public;

};

BOTAN_DIAGNOSTIC_PUSH

BOTAN_DIAGNOSTIC_IGNORE_INHERITED_VIA_DOMINANCE

class BOTAN_PUBLIC_API(2, 0) X25519_PrivateKey final : public X25519_PublicKey,

                                                       public virtual Private_Key,

                                                       public virtual PK_Key_Agreement_Key {

   public:

      /**

      * Construct a private key from the specified parameters.

      * @param alg_id the X.509 algorithm identifier

      * @param key_bits PKCS #8 structure

      */

      X25519_PrivateKey(const AlgorithmIdentifier& alg_id, std::span<const uint8_t> key_bits);

      /**

      * Generate a private key.

      * @param rng the RNG to use

      */

      explicit X25519_PrivateKey(RandomNumberGenerator& rng);

      /**

      * Construct a private key from the specified parameters.

      * @param secret_key the private key

      */

      explicit X25519_PrivateKey(const secure_vector<uint8_t>& secret_key);

      std::vector<uint8_t> public_value() const override { return X25519_PublicKey::public_value(); }

      secure_vector<uint8_t> agree(const uint8_t w[], size_t w_len) const;

      secure_vector<uint8_t> raw_private_key_bits() const override { return m_private; }

      BOTAN_DEPRECATED("Use raw_private_key_bits") const secure_vector<uint8_t>& get_x() const { return m_private; }

      secure_vector<uint8_t> private_key_bits() const override;

      std::unique_ptr<Public_Key> public_key() const override;

      bool check_key(RandomNumberGenerator& rng, bool strong) const override;

      std::unique_ptr<PK_Ops::Key_Agreement> create_key_agreement_op(RandomNumberGenerator& rng,

                                                                     std::string_view params,

                                                                     std::string_view provider) const override;

   private:

      secure_vector<uint8_t> m_private;

};

BOTAN_DIAGNOSTIC_POP

/*

* The types above are just wrappers for curve25519_donna, plus defining

* encodings for public and private keys.

*/

BOTAN_DEPRECATED_API("Use X25519_PrivateKey or Sodium::crypto_scalarmult_curve25519")

void curve25519_donna(uint8_t mypublic[32], const uint8_t secret[32], const uint8_t basepoint[32]);

/**

* Exponentiate by the x25519 base point

* @param mypublic output value

* @param secret random scalar

*/

BOTAN_DEPRECATED_API("Use X25519_PrivateKey or Sodium::crypto_scalarmult_curve25519_base")

void curve25519_basepoint(uint8_t mypublic[32], const uint8_t secret[32]);

}  // namespace Botan

#endif