This code would not really generate ephemeral keys every time it is called,
but a single key that would be reused during process lifetime and returned
each time the function was called; probably not what users would expect.
TLS allowes ephemeral keys to be used only when no other key exchange, such
as (ephemeral) Diffie-Hellman, is performed. The end result is that it was
only used by a number of (weak) export ciphers, which could give users a
false sense of security.
So, instead of fixing a weak cipher mode, we'll just remove support for it
completely. Plenty of better alternatives are available in TLS.
Signed-off-by: Steffan Karger <stef...@karger.me>
---
src/openvpn/ssl_openssl.c | 18 ------------------
1 file changed, 18 deletions(-)
diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c
index 1c6291f..08327a1 100644
--- a/src/openvpn/ssl_openssl.c
+++ b/src/openvpn/ssl_openssl.c
@@ -93,22 +93,6 @@ tls_clear_error()
ERR_clear_error ();
}
-/*
- * OpenSSL callback to get a temporary RSA key, mostly
- * used for export ciphers.
- */
-static RSA *
-tmp_rsa_cb (SSL * s, int is_export, int keylength)
-{
- static RSA *rsa_tmp = NULL;
- if (rsa_tmp == NULL)
- {
- msg (D_HANDSHAKE, "Generating temp (%d bit) RSA key", keylength);
- rsa_tmp = RSA_generate_key (keylength, RSA_F4, NULL, NULL);
- }
- return (rsa_tmp);
-}
-
void
tls_ctx_server_new(struct tls_root_ctx *ctx)
{
@@ -118,8 +102,6 @@ tls_ctx_server_new(struct tls_root_ctx *ctx)
if (ctx->ctx == NULL)
msg (M_SSLERR, "SSL_CTX_new SSLv23_server_method");
-
- SSL_CTX_set_tmp_rsa_callback (ctx->ctx, tmp_rsa_cb);
}
void
--
1.8.3.2
