more warnings for multiplication timings

Following CuleX's advice.

Whitelisted x86, x86_64, ARM, and ARM64.  Users should check
how multiplication is done on other platforms.

diff --git a/doc/man/man3/intro.3monocypher b/doc/man/man3/intro.3monocypher
index 0a3b3897f919fdbf557211c06d549fac76b3999a..86661243de8ca4dc92ad65d7bd96e281b3290ab5 100644 (file)
--- a/doc/man/man3/intro.3monocypher
+++ b/doc/man/man3/intro.3monocypher
@@ -174,6 +174,8 @@ destroy all security.
 .Pp
 The Poly1305 authenticator, X25519, and EdDSA use multiplication.
 Some older processors do not multiply in constant time.
+If the target platform is something other than x86, x86_64, ARM or
+ARM64, double check how it handles multiplication.
 .Pp
 .Sy The lengths of the inputs are not secret.
 Timings do reveal them \(en So do network traffic and file sizes.