mention nettle as the recommended crypto backend

diff --git a/doc/cha-crypto.texi b/doc/cha-crypto.texi
index 8c92deb116a6fc38c012c29ee9c548156744ccf2..24b1b4dd9a699fb4fab14f50729658fe74221afa 100644 (file)
--- a/doc/cha-crypto.texi
+++ b/doc/cha-crypto.texi
@@ -5,7 +5,8 @@
 it does not provide access to basic cryptographic primitives. However
 it abstracts the internal cryptographic back-end (see @ref{Cryptographic Backend}),
 providing symmetric crypto, hash and HMAC algorithms, as well access
-to the random number generation.
+to the random number generation. For a low-level crypto API the usage of nettle
+@footnote{See @uref{http://www.lysator.liu.se/~nisse/nettle/}.} library is recommended.
 
 @menu
 * Symmetric algorithms::