diff --git a/src/libsodium/crypto_sign/crypto_sign.c b/src/libsodium/crypto_sign/crypto_sign.c
index 187f7d6e..1f3b8560 100644
--- a/src/libsodium/crypto_sign/crypto_sign.c
+++ b/src/libsodium/crypto_sign/crypto_sign.c
@@ -1,6 +1,30 @@
 
 #include "crypto_sign.h"
 
+size_t
+crypto_sign_bytes(void)
+{
+    return crypto_sign_BYTES;
+}
+
+size_t
+crypto_sign_publickeybytes(void)
+{
+    return crypto_sign_PUBLICKEYBYTES;
+}
+
+size_t
+crypto_sign_secretkeybytes(void)
+{
+    return crypto_sign_SECRETKEYBYTES;
+}
+
+const char *
+crypto_sign_primitive(void)
+{
+    return crypto_sign_PRIMITIVE;
+}
+
 int
 crypto_sign_seed_keypair(unsigned char *pk, unsigned char *sk,
                          const unsigned char *seed)
diff --git a/src/libsodium/include/sodium/crypto_sign.h b/src/libsodium/include/sodium/crypto_sign.h
index 4e03e178..b0cc83a3 100644
--- a/src/libsodium/include/sodium/crypto_sign.h
+++ b/src/libsodium/include/sodium/crypto_sign.h
@@ -1,17 +1,26 @@
 #ifndef crypto_sign_H
 #define crypto_sign_H
 
-#include "crypto_sign_ed25519.h"
+#include <stdlib.h>
 
-#define crypto_sign_BYTES crypto_sign_ed25519_BYTES
-#define crypto_sign_PUBLICKEYBYTES crypto_sign_ed25519_PUBLICKEYBYTES
-#define crypto_sign_SECRETKEYBYTES crypto_sign_ed25519_SECRETKEYBYTES
-#define crypto_sign_PRIMITIVE "ed25519"
+#include "crypto_sign_ed25519.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+#define crypto_sign_BYTES crypto_sign_ed25519_BYTES
+size_t  crypto_sign_bytes(void);
+
+#define crypto_sign_PUBLICKEYBYTES crypto_sign_ed25519_PUBLICKEYBYTES
+size_t  crypto_sign_publickeybytes(void);
+
+#define crypto_sign_SECRETKEYBYTES crypto_sign_ed25519_SECRETKEYBYTES
+size_t  crypto_sign_secretkeybytes(void);
+
+#define crypto_sign_PRIMITIVE "ed25519"
+const char *crypto_sign_primitive(void);
+
 int crypto_sign_seed_keypair(unsigned char *pk, unsigned char *sk,
                              const unsigned char *seed);