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(** Tezos - X25519/XSalsa20-Poly1305 cryptography *)

type nonce = Bigstring.t
val nonce_size : int

val zero_nonce : nonce
val random_nonce : unit -> nonce
val increment_nonce : ?step:int -> nonce -> nonce

(** [generate_nonces ~incoming ~sent_msg ~recv_msg] generates two
    nonces by hashing (Blake2B) the arguments. The nonces should be
    used to initialize the encryption on the communication
    channels. Because an attacker cannot control both messages,
    it cannot determine the nonces that will be used to encrypt
    the messages. The sent message should contains a random nonce,
    and we should never send the exact same message twice. *)
val generate_nonces :
  incoming:bool -> sent_msg:MBytes.t -> recv_msg:MBytes.t -> nonce * nonce

module Secretbox : sig
  type key

  val unsafe_of_bytes : MBytes.t -> key

  val box_noalloc : key -> nonce -> MBytes.t -> unit
  val box_open_noalloc : key -> nonce -> MBytes.t -> bool

  val box : key -> MBytes.t -> nonce -> MBytes.t
  val box_open : key -> MBytes.t -> nonce -> MBytes.t option
end

type target
val default_target : target
val make_target : float -> target

type secret_key
type public_key
module Public_key_hash : S.HASH
type channel_key

val hash : public_key -> Public_key_hash.t

val zerobytes : int
val boxzerobytes : int

val random_keypair : unit -> secret_key * public_key * Public_key_hash.t

val precompute : secret_key -> public_key -> channel_key

val fast_box        : channel_key -> MBytes.t -> nonce -> MBytes.t
val fast_box_open   : channel_key -> MBytes.t -> nonce -> MBytes.t option

val fast_box_noalloc : channel_key -> nonce -> MBytes.t -> unit
val fast_box_open_noalloc : channel_key -> nonce -> MBytes.t -> bool

val check_proof_of_work : public_key -> nonce -> target -> bool
val generate_proof_of_work : ?max:int -> public_key -> target -> nonce

val public_key_to_bigarray : public_key -> Cstruct.buffer
val public_key_of_bigarray : Cstruct.buffer -> public_key
val public_key_size : int

val secret_key_to_bigarray : secret_key -> Cstruct.buffer
val secret_key_of_bigarray : Cstruct.buffer -> secret_key
val secret_key_size : int

val public_key_encoding : public_key Data_encoding.t
val secret_key_encoding : secret_key Data_encoding.t
val nonce_encoding : nonce Data_encoding.t