os: Add libnettle as a choice of SHA1 implementation

libnettle is smaller than libgcrypt, currently being released more
frequently, and has replaced the latter in gnutls-3.x (which is used
by TigerVNC, so they can avoid pulling in two crypto libraries
simultaneously).

Signed-off-by: Yaakov Selkowitz <yselkowitz@users.sourceforge.net>
Reviewed-by: Julien Cristau <jcristau@debian.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/os/xsha1.c b/os/xsha1.c
index fa66c7a06..24c0aa284 100644
--- a/os/xsha1.c
+++ b/os/xsha1.c
@@ -116,6 +116,36 @@ x_sha1_final(void *ctx, unsigned char result[20])
     return 1;
 }
 
+#elif defined(HAVE_SHA1_IN_LIBNETTLE)   /* Use libnettle for SHA1 */
+
+#include <nettle/sha.h>
+
+void *
+x_sha1_init(void)
+{
+    struct sha1_ctx *ctx = malloc(sizeof(*ctx));
+
+    if (!ctx)
+        return NULL;
+    sha1_init(ctx);
+    return ctx;
+}
+
+int
+x_sha1_update(void *ctx, void *data, int size)
+{
+    sha1_update(ctx, size, data);
+    return 1;
+}
+
+int
+x_sha1_final(void *ctx, unsigned char result[20])
+{
+    sha1_digest(ctx, 20, result);
+    free(ctx);
+    return 1;
+}
+
 #elif defined(HAVE_SHA1_IN_LIBGCRYPT)   /* Use libgcrypt for SHA1 */
 
 #include <gcrypt.h>