salt

%%% Copyright (c) 2013 Jachym Holecek <freza@circlewave.net>
%%% Copyright (c) 2014 Jihyun Yu <yjh0502@gmail.com>
%%% All rights reserved.
%%%
%%% Redistribution and use in source and binary forms, with or without
%%% modification, are permitted provided that the following conditions
%%% are met:
%%%
%%% 1. Redistributions of source code must retain the above copyright
%%%    notice, this list of conditions and the following disclaimer.
%%% 2. Redistributions in binary form must reproduce the above copyright
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%%% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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-module(salt).

-export([crypto_box_keypair/0, crypto_box/4, crypto_box_open/4, crypto_box_beforenm/2]).
-export([crypto_box_afternm/3, crypto_box_open_afternm/3]).
-export([crypto_scalarmult/2, crypto_scalarmult_base/1]).
-export([crypto_sign_keypair/0, crypto_sign/2, crypto_sign_open/2]).

-export([crypto_secretbox/3, crypto_secretbox_open/3]).
-export([crypto_stream/3, crypto_stream_xor/3]).
-export([crypto_auth/2, crypto_auth_verify/3]).
-export([crypto_onetimeauth/2, crypto_onetimeauth_verify/3]).

-export([crypto_hash/1, crypto_verify_16/2, crypto_verify_32/2]).
-export([crypto_random_bytes/1]).

%% -include_lib("salt/include/salt.hrl").
-include("salt.hrl").

%%% Public-key cryptography.

%% Public-key authenticated encryption.

-type resp_box() :: badarg | binary().
-type resp_box_open() :: badarg | forged_or_garbled | {ok, binary()}.
-type resp_auth() :: badarg | forged_or_garbled | authenticated.
-type resp_bool() :: equal | not_equal.

-spec crypto_box_keypair() -> {binary(), binary()}.
crypto_box_keypair() ->
    salt_nif:salt_box_keypair().

-spec crypto_box(iodata(), binary(), binary(), binary()) -> resp_box().
crypto_box(Plain_text, Nonce, Public_key, Secret_key) ->
    salt_nif:salt_box([crypto_box_zerobytes() | Plain_text], Nonce, Public_key, Secret_key).

-spec crypto_box_open(iodata(), binary(), binary(), binary()) ->
        badarg | forged_or_garbled | {ok, binary()}.
crypto_box_open(Cipher_text, Nonce, Public_key, Secret_key) ->
    salt_nif:salt_box_open([crypto_box_boxzerobytes() | Cipher_text], Nonce, Public_key, Secret_key).

-spec crypto_box_beforenm(binary(), binary()) -> resp_box().
crypto_box_beforenm(Public_key, Secret_key) ->
    salt_nif:salt_box_beforenm(Public_key, Secret_key).

-spec crypto_box_afternm(iodata(), binary(), binary()) -> resp_box().
crypto_box_afternm(Plain_text, Nonce, Context) ->
    salt_nif:salt_box_afternm([crypto_box_zerobytes() | Plain_text], Nonce, Context).

-spec crypto_box_open_afternm(iodata(), binary(), binary()) -> resp_box_open().
crypto_box_open_afternm(Cipher_text, Nonce, Context) ->
    salt_nif:salt_box_open_afternm([crypto_box_boxzerobytes() | Cipher_text], Nonce, Context).

%% Scalar multiplication. NB: Opaque representation of integers and group elements on fixed-length octet strings.
-spec crypto_scalarmult(binary(), binary()) -> resp_box().
crypto_scalarmult(Integer, Group_p) ->
    salt_nif:salt_scalarmult(Integer, Group_p).

-spec crypto_scalarmult_base(binary()) -> resp_box().
crypto_scalarmult_base(Integer) ->
    salt_nif:salt_scalarmult_base(Integer).

%% Signatures.
-spec crypto_sign_keypair() -> {binary(), binary()}.
crypto_sign_keypair() ->
    salt_nif:salt_sign_keypair().

-spec crypto_sign(iodata(), binary()) -> resp_box().
crypto_sign(Message, Secret_key) ->
    salt_nif:salt_sign([Message], Secret_key).

-spec crypto_sign_open(iodata(), binary()) -> resp_box_open().
crypto_sign_open(Signed_msg, Public_key) ->
    salt_nif:salt_sign_open([Signed_msg], Public_key).

%%% Secret-key cryptography.

%% Authenticated encryption.
-spec crypto_secretbox(iodata(), binary(), binary()) -> resp_box().
crypto_secretbox(Plain_text, Nonce, Secret_key) ->
    salt_nif:salt_secretbox([crypto_secretbox_zerobytes() | Plain_text], Nonce, Secret_key).

-spec crypto_secretbox_open(iodata(), binary(), binary()) -> resp_box_open().
crypto_secretbox_open(Cipher_text, Nonce, Secret_key) ->
    salt_nif:salt_secretbox_open([crypto_secretbox_boxzerobytes() | Cipher_text], Nonce, Secret_key).

%% Encryption.
-spec crypto_stream(pos_integer(), binary(), binary()) -> resp_box().
crypto_stream(Byte_cnt, Nonce, Secret_key) ->
    salt_nif:salt_stream(Byte_cnt, Nonce, Secret_key).

-spec crypto_stream_xor(binary(), binary(), binary()) -> resp_box().
crypto_stream_xor(Plain_text, Nonce, Secret_key) ->
    salt_nif:salt_stream_xor(Plain_text, Nonce, Secret_key).

%% Message authentication.
-spec crypto_auth(iodata(), binary()) -> resp_box().
crypto_auth(Message, Secret_key) ->
    salt_nif:salt_auth([Message], Secret_key).

-spec crypto_auth_verify(binary(), iodata(), binary()) -> resp_auth().
crypto_auth_verify(Authenticator, Message, Secret_key) ->
    salt_nif:salt_auth_verify(Authenticator, [Message], Secret_key).

%% Single-message authentication.
-spec crypto_onetimeauth(iodata(), binary()) -> resp_auth().
crypto_onetimeauth(Message, Secret_key) ->
    salt_nif:salt_onetimeauth([Message], Secret_key).

-spec crypto_onetimeauth_verify(binary(), iodata(), binary()) -> resp_auth().
crypto_onetimeauth_verify(Authenticator, Message, Secret_key) ->
    salt_nif:salt_onetimeauth_verify(Authenticator, [Message], Secret_key).

%%% Low-level functions.

%% Hashing.
-spec crypto_hash(iodata()) -> resp_box().
crypto_hash(Message) ->
    salt_nif:salt_hash([Message]).

%% String comparison.
-spec crypto_verify_16(binary(), binary()) -> resp_bool().
crypto_verify_16(Bin_x, Bin_y) ->
    salt_nif:salt_verify_16(Bin_x, Bin_y).

-spec crypto_verify_32(binary(), binary()) -> resp_bool().
crypto_verify_32(Bin_x, Bin_y) ->
    salt_nif:salt_verify_32(Bin_x, Bin_y).

%% Random number generator.
-spec crypto_random_bytes(pos_integer()) -> binary().
crypto_random_bytes(Cnt) ->
    salt_nif:salt_random_bytes(Cnt).

%%% Implementation.

crypto_secretbox_zerobytes() ->
    <<0:?CRYPTO_SECRETBOX_ZEROBYTES/integer-unit:8>>.

crypto_secretbox_boxzerobytes() ->
    <<0:?CRYPTO_SECRETBOX_BOXZEROBYTES/integer-unit:8>>.

crypto_box_zerobytes() ->
    <<0:?CRYPTO_BOX_ZEROBYTES/integer-unit:8>>.

crypto_box_boxzerobytes() ->
    <<0:?CRYPTO_BOX_BOXZEROBYTES/integer-unit:8>>.