Commit 4d89bf44 authored by Matt Caswell's avatar Matt Caswell
Browse files

Fix TLSv1.3 exporter 



We need to use the hashsize in generating the exportsecret not 0! Otherwise
we end up with random garbage for the secret.

It was pure chance that this passed the tests previously. It so happens
that, because we call SSL_export_keying_material() repeatedly for different
scenarios in the test, we end up in the tls13_export_keying_material() at
exactly the same position in the stack each time and therefore end up using
the same random garbage secret each time!

Reviewed-by: default avatarTim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3810)
parent 48feaceb

ssl/tls13_enc.c

+1 −1
Original line number Diff line number Diff line
@@ -622,7 +622,7 @@ int tls13_export_keying_material(SSL *s, unsigned char *out, size_t olen, 
            || EVP_DigestFinal_ex(ctx, hash, &hashsize) <= 0

            || !tls13_hkdf_expand(s, md, s->exporter_master_secret,

                                  (const unsigned char *)label, llen, NULL,

                                  exportsecret, 0)

                                  exportsecret, hashsize)

            || !tls13_hkdf_expand(s, md, exportsecret, exporterlabel,

                                  sizeof(exporterlabel) - 1, hash, out, olen))

        goto err;