text: /* Copyright (c) 2012-2019, The Tor Project, Inc. */
  /* See LICENSE for licensing information */
  
  /**
   * \file crypto_curve25519.h
   * \brief Header for crypto_curve25519.c
   **/
  
  #ifndef TOR_CRYPTO_CURVE25519_H
  #define TOR_CRYPTO_CURVE25519_H
  
  #include "lib/testsupport/testsupport.h"
  #include "lib/cc/torint.h"
  #include "lib/crypt_ops/crypto_digest.h"
  #include "lib/crypt_ops/crypto_openssl_mgt.h"
  #include "lib/defs/x25519_sizes.h"
  
  /** Wrapper type for a curve25519 public key.
   *
   *  (We define a separate type for these to make it less likely that we'll
   *  mistake them for secret keys.)
   * */
  typedef struct curve25519_public_key_t {
    uint8_t public_key[CURVE25519_PUBKEY_LEN];
  } curve25519_public_key_t;
  
  /** Wrapper type for a curve25519 secret key
   *
   * (We define a separate type for these to make it less likely that we'll
   * mistake them for public keys.)
   **/
  typedef struct curve25519_secret_key_t {
    uint8_t secret_key[CURVE25519_SECKEY_LEN];
  } curve25519_secret_key_t;
  
  /** A paired public and private key for curve25519. **/
  typedef struct curve25519_keypair_t {
    curve25519_public_key_t pubkey;
    curve25519_secret_key_t seckey;
  } curve25519_keypair_t;
  
  /* These functions require that we actually know how to use curve25519 keys.
   * The other data structures and functions in this header let us parse them,
   * store them, and move them around.
   */
  
  int curve25519_public_key_is_ok(const curve25519_public_key_t *);
  
  int curve25519_secret_key_generate(curve25519_secret_key_t *key_out,
                                     int extra_strong);
  void curve25519_public_key_generate(curve25519_public_key_t *key_out,
                                      const curve25519_secret_key_t *seckey);
  int curve25519_keypair_generate(curve25519_keypair_t *keypair_out,
                                  int extra_strong);
  
  void curve25519_handshake(uint8_t *output,
                            const curve25519_secret_key_t *,
                            const curve25519_public_key_t *);
  
  int curve25519_keypair_write_to_file(const curve25519_keypair_t *keypair,
                                       const char *fname,
                                       const char *tag);
  
  int curve25519_keypair_read_from_file(curve25519_keypair_t *keypair_out,
                                        char **tag_out,
                                        const char *fname);
  
  int curve25519_rand_seckey_bytes(uint8_t *out, int extra_strong);
  
  #ifdef CRYPTO_CURVE25519_PRIVATE
  STATIC int curve25519_impl(uint8_t *output, const uint8_t *secret,
                             const uint8_t *basepoint);
  
  STATIC int curve25519_basepoint_impl(uint8_t *output, const uint8_t *secret);
  #endif /* defined(CRYPTO_CURVE25519_PRIVATE) */
  
  int curve25519_public_from_base64(curve25519_public_key_t *pkey,
                                    const char *input);
  int curve25519_public_to_base64(char *output,
                                  const curve25519_public_key_t *pkey);
  
  void curve25519_set_impl_params(int use_ed);
  void curve25519_init(void);
  
  #endif /* !defined(TOR_CRYPTO_CURVE25519_H) */
  