/*
 * Derive private key from 256 bits of private seed.
 */
void myc_ed25519_create_privkey(unsigned char *private_key, const unsigned char *seed);

/*
 * Derive private and public key from 256 bits of private seed.
 */
 void myc_ed25519_create_keypair(unsigned char *public_key, unsigned char *private_key, const unsigned char *seed);

/*
 * Get ED25519 public key from private key.
 */
 void myc_ed25519_get_pubkey(unsigned char *public_key, const unsigned char *private_key);
 
 ```c
 /*
  * Sign message using key pair.
  */
 void myc_ed25519_sign(unsigned char *signature, const unsigned char *message, size_t message_len, const unsigned char *public_key, const unsigned char *private_key);

/*
 * Verify ED25519 signature
 */
int myc_ed25519_verify(const unsigned char *signature, const unsigned char *message, size_t message_len, const unsigned char *public_key);

/*
 * Tweak public or private key using the given scalar.
 */
int myc_ed25519_add_scalar(unsigned char *public_key, unsigned char *private_key, const unsigned char *scalar);

/*
 * ECDH shared key derivation
 */
void myc_ed25519_key_exchange(unsigned char *shared_secret, const unsigned char *public_key, const unsigned char *private_key);