add external dependencies in a pre-built way to avoid incompatibilities

external/include/sodium/crypto_kx.h

@@ -0,0 +1,66 @@
+#ifndef crypto_kx_H
+#define crypto_kx_H
+
+#include <stddef.h>
+
+#include "export.h"
+
+#ifdef __cplusplus
+# ifdef __GNUC__
+#  pragma GCC diagnostic ignored "-Wlong-long"
+# endif
+extern "C" {
+#endif
+
+#define crypto_kx_PUBLICKEYBYTES 32
+SODIUM_EXPORT
+size_t crypto_kx_publickeybytes(void);
+
+#define crypto_kx_SECRETKEYBYTES 32
+SODIUM_EXPORT
+size_t crypto_kx_secretkeybytes(void);
+
+#define crypto_kx_SEEDBYTES 32
+SODIUM_EXPORT
+size_t crypto_kx_seedbytes(void);
+
+#define crypto_kx_SESSIONKEYBYTES 32
+SODIUM_EXPORT
+size_t crypto_kx_sessionkeybytes(void);
+
+#define crypto_kx_PRIMITIVE "x25519blake2b"
+SODIUM_EXPORT
+const char *crypto_kx_primitive(void);
+
+SODIUM_EXPORT
+int crypto_kx_seed_keypair(unsigned char pk[crypto_kx_PUBLICKEYBYTES],
+                           unsigned char sk[crypto_kx_SECRETKEYBYTES],
+                           const unsigned char seed[crypto_kx_SEEDBYTES])
+            __attribute__ ((nonnull));
+
+SODIUM_EXPORT
+int crypto_kx_keypair(unsigned char pk[crypto_kx_PUBLICKEYBYTES],
+                      unsigned char sk[crypto_kx_SECRETKEYBYTES])
+            __attribute__ ((nonnull));
+
+SODIUM_EXPORT
+int crypto_kx_client_session_keys(unsigned char rx[crypto_kx_SESSIONKEYBYTES],
+                                  unsigned char tx[crypto_kx_SESSIONKEYBYTES],
+                                  const unsigned char client_pk[crypto_kx_PUBLICKEYBYTES],
+                                  const unsigned char client_sk[crypto_kx_SECRETKEYBYTES],
+                                  const unsigned char server_pk[crypto_kx_PUBLICKEYBYTES])
+            __attribute__ ((warn_unused_result))  __attribute__ ((nonnull(3, 4, 5)));
+
+SODIUM_EXPORT
+int crypto_kx_server_session_keys(unsigned char rx[crypto_kx_SESSIONKEYBYTES],
+                                  unsigned char tx[crypto_kx_SESSIONKEYBYTES],
+                                  const unsigned char server_pk[crypto_kx_PUBLICKEYBYTES],
+                                  const unsigned char server_sk[crypto_kx_SECRETKEYBYTES],
+                                  const unsigned char client_pk[crypto_kx_PUBLICKEYBYTES])
+            __attribute__ ((warn_unused_result))  __attribute__ ((nonnull(3, 4, 5)));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif