Fix client application traffic secret

A misreading of the TLS1.3 spec meant we were using the handshake hashes
up to and including the Client Finished to calculate the client
application traffic secret. We should be only use up until the Server
Finished.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2157)

1 files changed, 9 insertions, 2 deletions

diff --git a/test/tls13secretstest.c b/test/tls13secretstest.c
index 8734f2ae03..93b6e44257 100644
--- a/test/tls13secretstest.c
+++ b/test/tls13secretstest.c
@@ -186,12 +186,19 @@ static int test_secret(SSL *s, unsigned char *prk,
                        const unsigned char *ref_secret,
                        const unsigned char *ref_key, const unsigned char *ref_iv)
 {
-    size_t hashsize = EVP_MD_size(ssl_handshake_md(s));
+    size_t hashsize;
     unsigned char gensecret[EVP_MAX_MD_SIZE];
+    unsigned char hash[EVP_MAX_MD_SIZE];
     unsigned char key[KEYLEN];
     unsigned char iv[IVLEN];
 
-    if (!tls13_derive_secret(s, prk, label, labellen, gensecret)) {
+    if (!ssl_handshake_hash(s, hash, sizeof(hash), &hashsize)) {
+        fprintf(stderr, "Failed to get hash\n");
+        return 0;
+    }
+
+    if (!tls13_hkdf_expand(s, prk, label, labellen, hash, gensecret,
+                           hashsize)) {
         fprintf(stderr, "Secret generation failed\n");
         return 0;
     }