Add choice of ops and mem limits to pwhash_str

It natively checks atoms, which is kinda messy, but it avoids having to
export the libsodium pwhash constants, which is nice.

src/enacl.erl

@@ -101,6 +101,9 @@
          shorthash_size/0,
          shorthash/2,
 
+         %% No Tests!
+         pwhash_str/3,
+
          %% EQC
          pwhash/2,
          pwhash_str/1,
@@ -336,6 +339,7 @@ generichash_final({hashstate, HashSize, HashState}) ->
     enacl_nif:crypto_generichash_final(HashSize, HashState).
 
 
+-type pwhash_limit() :: interactive | moderate | sensitive | pos_integer().
 %% @doc pwhash/2 hash a password
 %%
 %% This function generates a fixed size salted hash of a user defined password.
@@ -347,10 +351,24 @@ pwhash(Password, Salt) ->
 %% @doc pwhash_str/1 generates a ASCII encoded hash of a password
 %%
 %% This function generates a fixed size, salted, ASCII encoded hash of a user defined password.
+%% Defaults to interactive/interactive limits.
 %% @end
 -spec pwhash_str(iodata()) -> {ok, iodata()} | {error, term()}.
 pwhash_str(Password) ->
-    case enacl_nif:crypto_pwhash_str(Password) of
+    pwhash_str(Password, interactive, interactive).
+
+%% @doc pwhash_str/3 generates a ASCII encoded hash of a password
+%%
+%% This function generates a fixed size, salted, ASCII encoded hash of a user defined password
+%% given Ops and Mem limits.
+%% @end
+-spec pwhash_str(Password, Ops, Mem) -> {ok, iodata()} | {error, term()}
+    when
+      Password :: iodata(),
+      Ops :: pwhash_limit(),
+      Mem :: pwhash_limit().
+pwhash_str(Password, Ops, Mem) ->
+    case enacl_nif:crypto_pwhash_str(Password, Ops, Mem) of
         {ok, ASCII} ->
             {ok, strip_null_terminate(ASCII)};
         {error, Reason} ->

src/enacl_nif.erl

@@ -133,7 +133,7 @@
 %% Password Hashing - Argon2 Algorithm
 -export([
          crypto_pwhash/2,
-         crypto_pwhash_str/1,
+         crypto_pwhash_str/3,
          crypto_pwhash_str_verify/2
         ]).
 
@@ -189,7 +189,7 @@ crypto_generichash_update(_HashSize, _HashState, _Message) ->  erlang:nif_error(
 crypto_generichash_final(_HashSize, _HashState) ->  erlang:nif_error(nif_not_loaded).
 
 crypto_pwhash(_Password, _Salt) -> erlang:nif_error(nif_not_loaded).
-crypto_pwhash_str(_Password) -> erlang:nif_error(nif_not_loaded).
+crypto_pwhash_str(_Password, _Ops, _Mem) -> erlang:nif_error(nif_not_loaded).
 crypto_pwhash_str_verify(_HashedPassword, _Password) -> erlang:nif_error(nif_not_loaded).
 
 crypto_box_NONCEBYTES() -> erlang:nif_error(nif_not_loaded).