curve25519.h

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/*
* Curve25519
* (C) 2014 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#ifndef BOTAN_CURVE_25519_H_
#define BOTAN_CURVE_25519_H_
 
#include <botan/pk_keys.h>
 
namespace Botan {
 
class BOTAN_PUBLIC_API(2,0) Curve25519_PublicKey : public virtual Public_Key
   {
   public:
      std::string algo_name() const override { return "Curve25519"; }
 
      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> 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);
         }
 
      /**
      * Create a Curve25519 Public Key.
      * @param alg_id the X.509 algorithm identifier
      * @param key_bits DER encoded public key bits
      */
      Curve25519_PublicKey(const AlgorithmIdentifier& alg_id,
                           std::span<const uint8_t> key_bits);
 
      /**
      * Create a Curve25519 Public Key.
      * @param pub 32-byte raw public key
      */
      explicit Curve25519_PublicKey(const std::vector<uint8_t>& pub) : m_public(pub) {}
 
      /**
      * Create a Curve25519 Public Key.
      * @param pub 32-byte raw public key
      */
      explicit Curve25519_PublicKey(const secure_vector<uint8_t>& pub) :
         m_public(pub.begin(), pub.end()) {}
 
   protected:
      Curve25519_PublicKey() = default;
      std::vector<uint8_t> m_public;
   };
 
BOTAN_DIAGNOSTIC_PUSH
BOTAN_DIAGNOSTIC_IGNORE_INHERITED_VIA_DOMINANCE
 
class BOTAN_PUBLIC_API(2,0) Curve25519_PrivateKey final : public Curve25519_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
      */
      Curve25519_PrivateKey(const AlgorithmIdentifier& alg_id,
                            std::span<const uint8_t> key_bits);
 
      /**
      * Generate a private key.
      * @param rng the RNG to use
      */
      explicit Curve25519_PrivateKey(RandomNumberGenerator& rng);
 
      /**
      * Construct a private key from the specified parameters.
      * @param secret_key the private key
      */
      explicit Curve25519_PrivateKey(const secure_vector<uint8_t>& secret_key);
 
      std::vector<uint8_t> public_value() const override { return Curve25519_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
 
typedef Curve25519_PublicKey X25519_PublicKey;
typedef Curve25519_PrivateKey X25519_PrivateKey;
 
/*
* The types above are just wrappers for curve25519_donna, plus defining
* encodings for public and private keys.
*/
void BOTAN_PUBLIC_API(2,0) 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
*/
void BOTAN_PUBLIC_API(2,0) curve25519_basepoint(uint8_t mypublic[32],
                                    const uint8_t secret[32]);
 
}
 
#endif