text: /* Copyright (c) 2012-2016, The Tor Project, Inc. */
  /* See LICENSE for licensing information */
  
  #ifndef TOR_CRYPTO_ED25519_H
  #define TOR_CRYPTO_ED25519_H
  
  #include "testsupport.h"
  #include "torint.h"
  #include "crypto_curve25519.h"
  
  #define ED25519_PUBKEY_LEN 32
  #define ED25519_SECKEY_LEN 64
  #define ED25519_SECKEY_SEED_LEN 32
  #define ED25519_SIG_LEN 64
  
  /** An Ed25519 signature. */
  typedef struct {
    uint8_t sig[ED25519_SIG_LEN];
  } ed25519_signature_t;
  
  /** An Ed25519 public key */
  typedef struct {
    uint8_t pubkey[ED25519_PUBKEY_LEN];
  } ed25519_public_key_t;
  
  /** An Ed25519 secret key */
  typedef struct {
    /** Note that we store secret keys in an expanded format that doesn't match
     * the format from standard ed25519.  Ed25519 stores a 32-byte value k and
     * expands it into a 64-byte H(k), using the first 32 bytes for a multiplier
     * of the base point, and second 32 bytes as an input to a hash function
     * for deriving r.  But because we implement key blinding, we need to store
     * keys in the 64-byte expanded form. */
    uint8_t seckey[ED25519_SECKEY_LEN];
  } ed25519_secret_key_t;
  
  /** An Ed25519 keypair. */
  typedef struct {
    ed25519_public_key_t pubkey;
    ed25519_secret_key_t seckey;
  } ed25519_keypair_t;
  
  int ed25519_secret_key_generate(ed25519_secret_key_t *seckey_out,
                              int extra_strong);
  int ed25519_secret_key_from_seed(ed25519_secret_key_t *seckey_out,
                                   const uint8_t *seed);
  
  int ed25519_public_key_generate(ed25519_public_key_t *pubkey_out,
                              const ed25519_secret_key_t *seckey);
  int ed25519_keypair_generate(ed25519_keypair_t *keypair_out, int extra_strong);
  int ed25519_sign(ed25519_signature_t *signature_out,
                   const uint8_t *msg, size_t len,
                   const ed25519_keypair_t *key);
  int ed25519_checksig(const ed25519_signature_t *signature,
                       const uint8_t *msg, size_t len,
                       const ed25519_public_key_t *pubkey);
  
  /**
   * A collection of information necessary to check an Ed25519 signature. Used
   * for batch verification.
   */
  typedef struct {
    /** The public key that supposedly generated the signature. */
    const ed25519_public_key_t *pubkey;
    /** The signature to check. */
    ed25519_signature_t signature;
    /** The message that the signature is supposed to have been applied to. */
    const uint8_t *msg;
    /** The length of the message. */
    size_t len;
  } ed25519_checkable_t;
  
  int ed25519_checksig_batch(int *okay_out,
                             const ed25519_checkable_t *checkable,
                             int n_checkable);
  
  int ed25519_keypair_from_curve25519_keypair(ed25519_keypair_t *out,
                                              int *signbit_out,
                                              const curve25519_keypair_t *inp);
  
  int ed25519_public_key_from_curve25519_public_key(ed25519_public_key_t *pubkey,
                                       const curve25519_public_key_t *pubkey_in,
                                       int signbit);
  int ed25519_keypair_blind(ed25519_keypair_t *out,
                            const ed25519_keypair_t *inp,
                            const uint8_t *param);
  int ed25519_public_blind(ed25519_public_key_t *out,
                           const ed25519_public_key_t *inp,
                           const uint8_t *param);
  
  /* XXXX read encrypted, write encrypted. */
  
  int ed25519_seckey_write_to_file(const ed25519_secret_key_t *seckey,
                                   const char *filename,
                                   const char *tag);
  int ed25519_seckey_read_from_file(ed25519_secret_key_t *seckey_out,
                                    char **tag_out,
                                    const char *filename);
  int ed25519_pubkey_write_to_file(const ed25519_public_key_t *pubkey,
                                   const char *filename,
                                   const char *tag);
  int ed25519_pubkey_read_from_file(ed25519_public_key_t *pubkey_out,
                                    char **tag_out,
                                    const char *filename);
  
  void ed25519_keypair_free(ed25519_keypair_t *kp);
  
  int ed25519_pubkey_eq(const ed25519_public_key_t *key1,
                        const ed25519_public_key_t *key2);
  
  void ed25519_set_impl_params(int use_donna);
  void ed25519_init(void);
  
  #ifdef TOR_UNIT_TESTS
  void crypto_ed25519_testing_force_impl(const char *name);
  void crypto_ed25519_testing_restore_impl(void);
  #endif
  
  #endif
  
  