From 39fa834e6f88ca68015eb5f91915ba681a7ce7ed Mon Sep 17 00:00:00 2001
From: Dennis Brentjes <d.brentjes@gmail.com>
Date: Fri, 18 Nov 2016 13:01:34 +0100
Subject: Made permutation a responsibility of cmix in the realtime phase.

---
 libcmix/cmix.c     | 19 +++++++++++++++++++
 libcmix/cmix.h     |  2 +-
 node/node_node.cpp | 28 +++++++++++++---------------
 3 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/libcmix/cmix.c b/libcmix/cmix.c
index 2ba5fd9..149bc7d 100644
--- a/libcmix/cmix.c
+++ b/libcmix/cmix.c
@@ -205,6 +205,25 @@ enum cmix_error permute_and_multiply_encrypted_s(struct CMixContext const* ctx,
 	return no_error;
 }
 
+enum cmix_error permute_and_multiply_s(struct CMixContext const* ctx, char** out_buffer, char const** message, size_t nr_elements) {
+	size_t el_size = get_group_element_array_size(ctx);
+	
+	for(size_t i = 0; i < nr_elements; ++i) {
+		unsigned int new_pos = ctx->permutation[i];
+		
+		GroupElement message_el = ctx->api.array_to_element(message[i], el_size, false);
+		GroupElement mult = ctx->api.multiply(message_el, ctx->s[new_pos], false);
+		
+		element_to_buffer(ctx, out_buffer[new_pos], mult);
+		
+		ctx->api.free_group_element(message_el);
+		ctx->api.free_group_element(mult);
+	}
+	
+	return no_error;
+}
+
+
 enum cmix_error multiply_s(struct CMixContext const* ctx, char* out_buffer, char const* message, size_t index) {
 	size_t el_size = get_group_element_array_size(ctx);
 	
diff --git a/libcmix/cmix.h b/libcmix/cmix.h
index f3d071d..689906c 100644
--- a/libcmix/cmix.h
+++ b/libcmix/cmix.h
@@ -87,7 +87,7 @@ enum cmix_error encrypt_r_and_multiply(struct CMixContext const* ctx, char* rand
 
 enum cmix_error permute_and_multiply_encrypted_s(struct CMixContext const* ctx, char** random_buffer, char** message_buffer, char const** random_element, char const** message_element, size_t nr_elements);
 
-enum cmix_error multiply_s(struct CMixContext const* ctx, char* out_buffer, char const* message, size_t index);
+enum cmix_error permute_and_multiply_s(struct CMixContext const* ctx, char** out_buffer, char const** message, size_t nr_elements);
 
 enum cmix_error get_key_exchange_value(struct CMixContext const* ctx, char* buffer, GroupElement priv_element);
 
diff --git a/node/node_node.cpp b/node/node_node.cpp
index 1742035..8faa4cf 100644
--- a/node/node_node.cpp
+++ b/node/node_node.cpp
@@ -160,25 +160,23 @@ cmix_proto::RealMix fill_realtime_mix_message(CMixContext& ctx, T const& ms) {
 	cmix_proto::RealMix realmix;
 	
 	size_t len = get_group_element_array_size(&ctx);
-	
-	for(int i = 0; i < ms.size(); ++i) {
-		realmix.add_m();
-	}
-	
+	std::vector<char*> mv(ms.size(), nullptr);
+	std::vector<char const*> msv(ms.size(), nullptr);
 	for(int i = 0; i < ms.size(); ++i) {
-		auto new_pos = ctx.permutation[i];
-		
-		realmix.mutable_m(new_pos)->resize(len);
-		
-		multiply_s(
-			&ctx,
-			&(*realmix.mutable_m(new_pos))[0],
-			ms.Get(i).data(),
-			i
-		);
+		std::string* m = realmix.add_m();
+		m->resize(len);
+		mv[i] = &(*m)[0];
 		
+		msv[i] = ms.Get(i).data();
 	}
 	
+	permute_and_multiply_s(
+		&ctx,
+		mv.data(),
+		msv.data(),
+		ms.size()
+	);
+	
 	return realmix;
 }
 
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