7 files changed, 127 insertions, 12 deletions
diff --git a/libcmix-crypto/curve25519/CMakeLists.txt b/libcmix-crypto/curve25519/CMakeLists.txt
index dc29c4d..ba79d87 100644
--- a/libcmix-crypto/curve25519/CMakeLists.txt
+++ b/libcmix-crypto/curve25519/CMakeLists.txt
@@ -10,17 +10,23 @@ target_sources(curve25519-interface
 )
 
 target_link_libraries(curve25519-interface
-	INTERFACE cmix-crypto
+	INTERFACE cmix-crypto-interface
 )
 
 foreach(impl ${curve25519_implementations})
 	add_subdirectory(${impl})
 endforeach()
 
-add_library(curve25519-implementation INTERFACE)
+add_library(curve25519-implementation
+	curve25519.h curve25519.c
+)
+
+target_include_directories(curve25519-implementation
+	PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}
+)
 
 target_link_libraries(curve25519-implementation
-	INTERFACE curve25519-${curve25519_implementation}
+	PUBLIC curve25519-${curve25519_implementation}
 )
 
 
diff --git a/libcmix-crypto/curve25519/curve25519.c b/libcmix-crypto/curve25519/curve25519.c
new file mode 100644
index 0000000..824daf9
--- /dev/null
+++ b/libcmix-crypto/curve25519/curve25519.c
@@ -0,0 +1,12 @@
+
+#include "curve25519.h"
+
+struct Api get_curve25519_implementation()
+{
+	return (struct Api) {
+		&curve25519_create_keypair,
+		&curve25519_keypair_deleter,
+		&curve25519_derive_shared_key,
+		&curve25519_shared_key_deleter
+	};
+}
diff --git a/libcmix-crypto/curve25519/curve25519.h b/libcmix-crypto/curve25519/curve25519.h
index 319e693..ef466a3 100644
--- a/libcmix-crypto/curve25519/curve25519.h
+++ b/libcmix-crypto/curve25519/curve25519.h
@@ -4,11 +4,18 @@
 extern "C" {
 #endif
 
-#include "keypair.h"
+#include "api.h"
 
 #include <stdlib.h>
 
+
 extern struct KeyPair curve25519_create_keypair();
+extern void curve25519_keypair_deleter(struct KeyPair p);
+
+extern struct SharedKey curve25519_derive_shared_key(struct KeyPair pair, unsigned char* pub_key, bool swap_pub_order);
+extern void curve25519_shared_key_deleter(struct SharedKey s);
+
+struct Api get_curve25519_implementation();
 
 #ifdef __cplusplus
 }
diff --git a/libcmix-crypto/curve25519/null/CMakeLists.txt b/libcmix-crypto/curve25519/null/CMakeLists.txt
new file mode 100644
index 0000000..bf30adc
--- /dev/null
+++ b/libcmix-crypto/curve25519/null/CMakeLists.txt
@@ -0,0 +1,17 @@
+include(get_target_name)
+
+get_target_name(target_name)
+
+add_library(${target_name} SHARED
+	null_curve25519.c
+)
+
+target_compile_options(${target_name}
+	PRIVATE -std=c99
+)
+
+target_link_libraries(${target_name}
+	INTERFACE cmix-crypto
+	PRIVATE curve25519-interface
+	PUBLIC sodium
+)
diff --git a/libcmix-crypto/curve25519/null/null_curve25519.c b/libcmix-crypto/curve25519/null/null_curve25519.c
new file mode 100644
index 0000000..317455f
--- /dev/null
+++ b/libcmix-crypto/curve25519/null/null_curve25519.c
@@ -0,0 +1,25 @@
+
+#include "api.h"
+
+#include <stddef.h>
+#include <stdbool.h>
+
+void curve25519_keypair_deleter(struct KeyPair p) {}
+
+struct KeyPair curve25519_create_keypair() {
+	return (struct KeyPair){
+		NULL,
+		NULL,
+		0,
+		0
+	};
+}
+
+void curve25519_shared_key_deleter(struct SharedKey s) {}
+
+struct SharedKey curve25519_derive_shared_key(struct KeyPair pair, unsigned char* pub_key, bool swap_pub_order) {
+	return (struct SharedKey){
+		NULL,
+		0
+	};
+}
diff --git a/libcmix-crypto/curve25519/sodium/CMakeLists.txt b/libcmix-crypto/curve25519/sodium/CMakeLists.txt
index 213a49f..7679a88 100644
--- a/libcmix-crypto/curve25519/sodium/CMakeLists.txt
+++ b/libcmix-crypto/curve25519/sodium/CMakeLists.txt
@@ -2,9 +2,9 @@ include(get_target_name)
 
 get_target_name(target_name)
 
-include(ImportSodium)
+find_package(sodium REQUIRED CONFIG)
 
-add_library(${target_name}
+add_library(${target_name} SHARED
 	libsodium_curve25519.c
 )
 
@@ -13,6 +13,7 @@ target_compile_options(${target_name}
 )
 
 target_link_libraries(${target_name}
-	PUBLIC curve25519-interface
-	PUBLIC Sodium
+	INTERFACE cmix-crypto
+	PRIVATE curve25519-interface
+	PUBLIC sodium
 )
diff --git a/libcmix-crypto/curve25519/sodium/libsodium_curve25519.c b/libcmix-crypto/curve25519/sodium/libsodium_curve25519.c
index 8fd087a..59e9258 100644
--- a/libcmix-crypto/curve25519/sodium/libsodium_curve25519.c
+++ b/libcmix-crypto/curve25519/sodium/libsodium_curve25519.c
@@ -12,9 +12,12 @@ void init() {
 	}
 }
 
-void sodium_curve25519_keypair_deleter(struct KeyPair* p) {
-	sodium_free(p->sec);
-	free(p->pub);
+void curve25519_keypair_deleter(struct KeyPair p) {
+	sodium_free(p.sec);
+	free(p.pub);
+
+	p.sec = NULL;
+	p.pub = NULL;
 }
 
 struct KeyPair curve25519_create_keypair() {
@@ -26,5 +29,49 @@ struct KeyPair curve25519_create_keypair() {
 	randombytes_buf(sec, crypto_box_SECRETKEYBYTES);
 	crypto_scalarmult_base(pub, sec);
 
-	return (struct KeyPair){sec, pub, crypto_box_SECRETKEYBYTES, crypto_box_PUBLICKEYBYTES, &sodium_curve25519_keypair_deleter};
+	return (struct KeyPair){
+		sec,
+		pub,
+		crypto_box_SECRETKEYBYTES,
+		crypto_box_PUBLICKEYBYTES
+	};
+}
+
+void curve25519_shared_key_deleter(struct SharedKey s) {
+	sodium_free(s.shared);
+
+	s.shared = NULL;
+}
+
+struct SharedKey curve25519_derive_shared_key(struct KeyPair pair, unsigned char* pub_key, bool swap_pub_order) {
+	init();
+
+	unsigned char* shared = (unsigned char*) sodium_malloc(crypto_generichash_BYTES);
+
+	crypto_generichash_state h;
+
+	unsigned char* scalarmult_q = (unsigned char*) sodium_malloc(crypto_scalarmult_BYTES);
+
+	if (crypto_scalarmult(scalarmult_q, pair.sec, pub_key) != 0) {
+		exit(-1);
+	}
+
+	crypto_generichash_init(&h, NULL, 0U, crypto_generichash_BYTES);
+	crypto_generichash_update(&h, scalarmult_q, crypto_scalarmult_BYTES);
+	if(swap_pub_order) {
+		crypto_generichash_update(&h, pub_key, crypto_box_PUBLICKEYBYTES);
+		crypto_generichash_update(&h, pair.pub, crypto_box_PUBLICKEYBYTES);
+	} else {
+		crypto_generichash_update(&h, pair.pub, crypto_box_PUBLICKEYBYTES);
+		crypto_generichash_update(&h, pub_key, crypto_box_PUBLICKEYBYTES);
+	}
+	crypto_generichash_final(&h, shared, crypto_generichash_BYTES);
+
+	sodium_free(scalarmult_q);
+
+	return (struct SharedKey){
+		shared,
+		crypto_generichash_BYTES
+	};
 }
+