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

external/include/sodium/crypto_kdf.h

@@ -0,0 +1,53 @@
+#ifndef crypto_kdf_H
+#define crypto_kdf_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "crypto_kdf_blake2b.h"
+#include "export.h"
+
+#ifdef __cplusplus
+# ifdef __GNUC__
+#  pragma GCC diagnostic ignored "-Wlong-long"
+# endif
+extern "C" {
+#endif
+
+#define crypto_kdf_BYTES_MIN crypto_kdf_blake2b_BYTES_MIN
+SODIUM_EXPORT
+size_t crypto_kdf_bytes_min(void);
+
+#define crypto_kdf_BYTES_MAX crypto_kdf_blake2b_BYTES_MAX
+SODIUM_EXPORT
+size_t crypto_kdf_bytes_max(void);
+
+#define crypto_kdf_CONTEXTBYTES crypto_kdf_blake2b_CONTEXTBYTES
+SODIUM_EXPORT
+size_t crypto_kdf_contextbytes(void);
+
+#define crypto_kdf_KEYBYTES crypto_kdf_blake2b_KEYBYTES
+SODIUM_EXPORT
+size_t crypto_kdf_keybytes(void);
+
+#define crypto_kdf_PRIMITIVE "blake2b"
+SODIUM_EXPORT
+const char *crypto_kdf_primitive(void)
+            __attribute__ ((warn_unused_result));
+
+SODIUM_EXPORT
+int crypto_kdf_derive_from_key(unsigned char *subkey, size_t subkey_len,
+                               uint64_t subkey_id,
+                               const char ctx[crypto_kdf_CONTEXTBYTES],
+                               const unsigned char key[crypto_kdf_KEYBYTES])
+            __attribute__ ((nonnull));
+
+SODIUM_EXPORT
+void crypto_kdf_keygen(unsigned char k[crypto_kdf_KEYBYTES])
+            __attribute__ ((nonnull));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif