From 41045fed85270d3a620bae830e07ee4b559aa3ba Mon Sep 17 00:00:00 2001
From: Jesper Louis Andersen <jesper.louis.andersen@gmail.com>
Date: Wed, 5 Feb 2020 13:16:35 +0100
Subject: [PATCH] Partially stream kx

Also while here, implement some EQC tests for it.
---
 CHANGELOG.md           |  3 ++-
 c_src/enacl.c          |  2 +-
 c_src/kx.c             | 14 +++++++-------
 eqc_test/enacl_eqc.erl | 29 +++++++++++++++++++++++++++++
 4 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f8794ff..39211d8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,15 +10,16 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Go through all calls and make them return streamlined exceptions if applicable.
   Pretty large change, but OTOH, this ought to happen before a 1.0 release as well.
   - kx
+    - Rename the key sizes so they follow libsodium.
   - secret
   - sign
-  - enacl_nif
 
 - Implement missing EQC tests
   - Generichash
   - Multi-part generic hash
   - pwhash
     - Extend with limit for ops and memory as well.
+  - kx
 
 ## [Unreleased]
 
diff --git a/c_src/enacl.c b/c_src/enacl.c
index fa8a71b..5497180 100644
--- a/c_src/enacl.c
+++ b/c_src/enacl.c
@@ -8,5 +8,5 @@ ERL_NIF_TERM enacl_error_tuple(ErlNifEnv *env, char *error_atom) {
 }
 
 ERL_NIF_TERM enacl_internal_error(ErlNifEnv *env) {
-  return enif_raise_exception(env, enif_make_atom(env, "internal_error"));
+  return enif_raise_exception(env, enif_make_atom(env, "enacl_internal_error"));
 }
\ No newline at end of file
diff --git a/c_src/kx.c b/c_src/kx.c
index 6d5b39b..6020e6f 100644
--- a/c_src/kx.c
+++ b/c_src/kx.c
@@ -31,12 +31,12 @@ ERL_NIF_TERM enacl_crypto_kx_keypair(ErlNifEnv *env, int argc,
   }
 
   if (!enif_alloc_binary(crypto_kx_PUBLICKEYBYTES, &pk)) {
-    return enacl_error_tuple(env, "alloc_failed");
+    return enacl_internal_error(env);
   }
 
   if (!enif_alloc_binary(crypto_kx_SECRETKEYBYTES, &sk)) {
     enif_release_binary(&pk);
-    return enacl_error_tuple(env, "alloc_failed");
+    return enacl_internal_error(env);
   }
 
   crypto_kx_keypair(pk.data, sk.data);
@@ -68,12 +68,12 @@ enacl_crypto_kx_server_session_keys(ErlNifEnv *env, int argc,
     goto bad_arg;
 
   if (!enif_alloc_binary(crypto_kx_SESSIONKEYBYTES, &rx)) {
-    ret = enacl_error_tuple(env, "alloc_failed");
+    ret = enacl_internal_error(env);
     goto done;
   }
 
   if (!enif_alloc_binary(crypto_kx_SESSIONKEYBYTES, &tx)) {
-    ret = enacl_error_tuple(env, "alloc_failed");
+    ret = enacl_internal_error(env);
     goto release_rx;
   }
 
@@ -121,12 +121,12 @@ enacl_crypto_kx_client_session_keys(ErlNifEnv *env, int argc,
     goto bad_arg;
 
   if (!enif_alloc_binary(crypto_kx_SESSIONKEYBYTES, &rx)) {
-    ret = enacl_error_tuple(env, "alloc_failed");
+    ret = enacl_internal_error(env);
     goto done;
   }
 
   if (!enif_alloc_binary(crypto_kx_SESSIONKEYBYTES, &tx)) {
-    ret = enacl_error_tuple(env, "alloc_failed");
+    ret = enacl_internal_error(env);
     goto release_rx;
   }
 
@@ -148,4 +148,4 @@ release_rx:
   enif_release_binary(&rx);
 done:
   return ret;
-}
\ No newline at end of file
+}
diff --git a/eqc_test/enacl_eqc.erl b/eqc_test/enacl_eqc.erl
index 7eb1486..4b6f4ac 100644
--- a/eqc_test/enacl_eqc.erl
+++ b/eqc_test/enacl_eqc.erl
@@ -122,6 +122,24 @@ keypair_bad() ->
 keypair() ->
     ?FAULT(keypair_bad(), keypair_good()).
 
+kx_keypair_good() ->
+  #{ public := PK, secret := SK} = enacl:kx_keypair(),
+  {PK, SK}.
+
+kx_keypair_bad() ->
+  ?LET(X, elements([pk, sk]),
+  begin
+    #{ public := PK, secret := SK} = enacl:box_keypair(),
+    case X of
+      pk ->
+        PKBytes = enacl:kx_public_key_size(),
+        {oneof([return(a), nat(), ?SUCHTHAT(B, binary(), byte_size(B) /= PKBytes)]), SK};
+      sk ->
+        SKBytes = enacl:kx_secret_key_size(),
+        {PK, oneof([return(a), nat(), ?SUCHTHAT(B, binary(), byte_size(B) /= SKBytes)])}
+    end
+  end).
+
 %% CRYPTO BOX
 %% ---------------------------
 %% * box/4
@@ -880,6 +898,17 @@ prop_randombytes_uint32() ->
       is_integer(V)
     end).
 
+%% KX
+%% ---------------------------
+prop_kx() ->
+  ?FORALL({{CPK, CSK}, {SPK, SSK}}, {kx_keypair_good(), kx_keypair_good()},
+  begin
+    #{ client_tx := CTX, client_rx := CRX} = enacl:kx_client_session_keys(CPK, CSK, SPK),
+    #{ server_tx := STX, server_rx := SRX} = enacl:kx_server_session_keys(SPK, SSK, CPK),
+    %% This keypair must be shared in both directions
+    conjunction([{ctx_srx, equals(CTX, SRX)}, {stx_crx, equals(STX, CRX)}])
+  end).
+
 %% SCRAMBLING
 prop_scramble_block() ->
     ?FORALL({Block, Key}, {binary(16), eqc_gen:largebinary(32)},