forked from QPQ-AG/enoise
Hans Svensson
81 lines
2.6 KiB
Erlang
81 lines
2.6 KiB
Erlang
%%% ------------------------------------------------------------------
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%%% @copyright 2018, Aeternity Anstalt
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%%%
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%%% @doc Module is an abstract data type for a key pair.
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%%%
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%%% @end
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%%% ------------------------------------------------------------------
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-module(enoise_keypair).
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-export([ key_type/1
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, new/1
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, new/2
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, new/3
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, pubkey/1
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, seckey/1
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]).
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-type key_type() :: dh25519 | dh448.
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-record(kp, { type :: key_type()
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, sec :: binary() | undefined
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, pub :: binary() }).
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-opaque keypair() :: #kp{}.
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%% Abstract keypair holding a secret key/public key pair and its type.
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-export_type([keypair/0]).
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%% @doc Generate a new keypair of type `Type'.
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-spec new(Type :: key_type()) -> keypair().
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new(Type) ->
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{Sec, Pub} = new_key_pair(Type),
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#kp{ type = Type, sec = Sec, pub = Pub }.
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%% @doc Create a new keypair of type `Type'. If `Public' is `undefined'
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%% it will be computed from the `Secret' (using the curve/algorithm
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%% indicated by `Type').
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-spec new(Type :: key_type(),
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Secret :: binary() | undefined,
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Public :: binary() | undefined) -> keypair().
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new(Type, Secret, undefined) ->
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new(Type, Secret, pubkey_from_secret(Type, Secret));
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new(Type, Secret, Public) ->
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#kp{ type = Type, sec = Secret, pub = Public }.
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%% @doc Define a "public only" keypair - holding just a public key and
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%% `undefined' for secret key.
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-spec new(Type :: key_type(), Public :: binary()) -> keypair().
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new(Type, Public) ->
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#kp{ type = Type, sec = undefined, pub = Public }.
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%% @doc Accessor function - return the key type of the key pair.
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-spec key_type(KeyPair :: keypair()) -> key_type().
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key_type(#kp{ type = T }) ->
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T.
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%% @doc Accessor function - return the public key of the key pair.
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-spec pubkey(KeyPair :: keypair()) -> binary().
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pubkey(#kp{ pub = P }) ->
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P.
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%% @doc Accessor function - return the secret key of the key pair.
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%% This function will throw an error if the key pair is "public only".
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-spec seckey(KeyPair :: keypair()) -> binary().
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seckey(#kp{ sec = undefined }) ->
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error(keypair_is_public_only);
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seckey(#kp{ sec = S }) ->
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S.
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%% -- Local functions --------------------------------------------------------
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new_key_pair(dh25519) ->
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KeyPair = enacl:crypto_sign_ed25519_keypair(),
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{enacl:crypto_sign_ed25519_secret_to_curve25519(maps:get(secret, KeyPair)),
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enacl:crypto_sign_ed25519_public_to_curve25519(maps:get(public, KeyPair))};
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new_key_pair(Type) ->
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error({unsupported_key_type, Type}).
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pubkey_from_secret(dh25519, Secret) ->
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enacl:curve25519_scalarmult_base(Secret).
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