diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index 2ce43fb0..0775fad2 100644
--- a/lib/libwebsockets.c
+++ b/lib/libwebsockets.c
@@ -427,6 +427,12 @@ int libwebsockets_get_random(struct libwebsocket_context *context,
 	return n;
 }
 
+unsigned char *
+libwebsockets_SHA1(const unsigned char *d, size_t n, unsigned char *md)
+{
+	return SHA1(d, n, md);
+}
+
 void libwebsockets_00_spaceout(char *key, int spaces, int seed)
 {
 	char *p;
diff --git a/lib/libwebsockets.h b/lib/libwebsockets.h
index b9eca98a..ec55ec82 100644
--- a/lib/libwebsockets.h
+++ b/lib/libwebsockets.h
@@ -640,6 +640,9 @@ extern int
 libwebsockets_get_random(struct libwebsocket_context *context,
 							    void *buf, int len);
 
+extern unsigned char *
+libwebsockets_SHA1(const unsigned char *d, size_t n, unsigned char *md);
+
 extern struct libwebsocket_extension libwebsocket_internal_extensions[];
 
 #ifdef WIN32