From b67352349f7a18a4318b11a1fba23878bd173b91 Mon Sep 17 00:00:00 2001 From: Fabio Scotoni <34964387+fscoto@users.noreply.github.com> Date: Tue, 31 Mar 2020 13:39:37 +0200 Subject: [PATCH] crypto_x25519: Note that _from_eddsa exists --- doc/man/man3/crypto_x25519.3monocypher | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/doc/man/man3/crypto_x25519.3monocypher b/doc/man/man3/crypto_x25519.3monocypher index 0aa8b45..e39c0d4 100644 --- a/doc/man/man3/crypto_x25519.3monocypher +++ b/doc/man/man3/crypto_x25519.3monocypher @@ -52,7 +52,7 @@ .\" with this software. If not, see .\" .\" -.Dd March 2, 2020 +.Dd March 31, 2020 .Dt CRYPTO_X25519 3MONOCYPHER .Os .Sh NAME @@ -128,6 +128,15 @@ compare the output of to an all-zero buffer using .Xr crypto_verify32 3monocypher ; abort the protocol if the output and the all-zero buffer are equal. +.Pp +Do not use the same secret key for both key exchanges and signatures. +The public keys are different, and revealing both may leak information. +If there really is no room to store or derive two different secret keys, +consider generating a key pair for signatures and then converting it +with +.Xr crypto_from_eddsa_private 3monocypher +and +.Xr crypto_from_eddsa_public 3monocypher . .Sh RETURN VALUES .Fn crypto_x25519 and -- 2.47.3