1 files changed, 24 insertions, 1 deletions

diff --git a/src/lib/libssl/tls12_lib.c b/src/lib/libssl/tls12_lib.c
index 520f41678d..e7171ba833 100644
--- a/src/lib/libssl/tls12_lib.c
+++ b/src/lib/libssl/tls12_lib.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: tls12_lib.c,v 1.1 2021/04/25 13:15:23 jsing Exp $ */
+/*      $OpenBSD: tls12_lib.c,v 1.2 2021/04/30 19:26:45 jsing Exp $ */
 /*
  * Copyright (c) 2021 Joel Sing <jsing@openbsd.org>
  *
@@ -90,3 +90,26 @@ tls12_derive_peer_finished(SSL *s)
                     &S3I(s)->hs.peer_finished_len);
         }
 }
+
+int
+tls12_derive_master_secret(SSL *s, uint8_t *premaster_secret,
+    size_t premaster_secret_len)
+{
+        s->session->master_key_length = 0;
+
+        if (premaster_secret_len == 0)
+                return 0;
+
+        CTASSERT(sizeof(s->session->master_key) == SSL_MAX_MASTER_KEY_LENGTH);
+
+        if (!tls1_PRF(s, premaster_secret, premaster_secret_len,
+            TLS_MD_MASTER_SECRET_CONST, TLS_MD_MASTER_SECRET_CONST_SIZE,
+            s->s3->client_random, SSL3_RANDOM_SIZE, NULL, 0,
+            s->s3->server_random, SSL3_RANDOM_SIZE, NULL, 0,
+            s->session->master_key, sizeof(s->session->master_key)))
+                return 0;
+
+        s->session->master_key_length = SSL_MAX_MASTER_KEY_LENGTH;
+
+        return 1;
+}