python · planetf1 · May 20, 2024 · Jun 4, 2024 · Jun 3, 2024 · Jun 4, 2024
@@ -1769,6 +1769,10 @@ to speed up repeated connections from the same clients.
    a well-known elliptic curve, for example ``prime256v1`` for a widely
    supported curve.
 
+   For OpenSSL 3.0 and above *curve_name* parameter can be a colon separated
+   list of curves, for example ``prime256v1:brainpoolP384r1`` specifies two curves that will be
+   used on a client hello.
+
    This setting doesn't apply to client sockets.  You can also use the
    :data:`OP_SINGLE_ECDH_USE` option to further improve security.
 

@@ -1375,11 +1375,29 @@ def test_set_ecdh_curve(self):
         ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
         ctx.set_ecdh_curve("prime256v1")
         ctx.set_ecdh_curve(b"prime256v1")
+        # Only OpenSSL 3 and above supported for multiple curves
+        if (IS_OPENSSL_3_0_0 >= 3):
+            ctx.set_ecdh_curve("prime256v1:brainpoolP384r1")
+            ctx.set_ecdh_curve(b"prime256v1:brainpoolP384r1")
         self.assertRaises(TypeError, ctx.set_ecdh_curve)
         self.assertRaises(TypeError, ctx.set_ecdh_curve, None)
         self.assertRaises(ValueError, ctx.set_ecdh_curve, "foo")
         self.assertRaises(ValueError, ctx.set_ecdh_curve, b"foo")
-
+        # Multiple bad curves should cause error for any OpenSSL version
+        self.assertRaises(ValueError, ctx.set_ecdh_curve, "foo:bar")
+        self.assertRaises(ValueError, ctx.set_ecdh_curve, b"foo:bar")
+        self.assertRaises(ValueError, ctx.set_ecdh_curve, "prime256v1:bar")
+        self.assertRaises(ValueError, ctx.set_ecdh_curve, b"prime256v1:bar")
+        self.assertRaises(ValueError, ctx.set_ecdh_curve, "foo:prime256v1")
+        self.assertRaises(ValueError, ctx.set_ecdh_curve, b"foo:prime256v1")
+        #self.assertRaises(ValueError, ctx.set_ecdh_curve, ":")
+        #self.assertRaises(ValueError, ctx.set_ecdh_curve, b":")
+        #self.assertRaises(ValueError, ctx.set_ecdh_curve, "::")
+        #self.assertRaises(ValueError, ctx.set_ecdh_curve, b"::")
+        #self.assertRaises(ValueError, ctx.set_ecdh_curve, "prime256v1:")
+        #self.assertRaises(ValueError, ctx.set_ecdh_curve, b"prime256v1:")
+        #self.assertRaises(ValueError, ctx.set_ecdh_curve, ":prime256v1")
+        #self.assertRaises(ValueError, ctx.set_ecdh_curve, b":prime256v1")
     def test_sni_callback(self):
         ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
 

diff --git a/Misc/NEWS.d/next/Library/2024-06-04-07-28-18.gh-issue-109945.02TejW.rst b/Misc/NEWS.d/next/Library/2024-06-04-07-28-18.gh-issue-109945.02TejW.rst
@@ -0,0 +1 @@
+Adds support for multiple curves to be specified in SSLContext.set_ecdh_curve() for OpenSSL 3.0 and above by setting curve_name to a colon separated list of curves. This allows multiple curves to be passed on a TLS client hello.
@@ -4379,18 +4379,19 @@ _ssl__SSLContext_set_ecdh_curve(PySSLContext *self, PyObject *name)
 /*[clinic end generated code: output=23022c196e40d7d2 input=c2bafb6f6e34726b]*/
 {
     PyObject *name_bytes;
-    int nid;
+
     if (!PyUnicode_FSConverter(name, &name_bytes))
         return NULL;
     assert(PyBytes_Check(name_bytes));
+#if OPENSSL_VERSION_MAJOR < 3
+    int nid;
     nid = OBJ_sn2nid(PyBytes_AS_STRING(name_bytes));
     Py_DECREF(name_bytes);
     if (nid == 0) {
         PyErr_Format(PyExc_ValueError,
                      "unknown elliptic curve name %R", name);
         return NULL;
     }
-#if OPENSSL_VERSION_MAJOR < 3
     EC_KEY *key = EC_KEY_new_by_curve_name(nid);
     if (key == NULL) {
         _setSSLError(get_state_ctx(self), NULL, 0, __FILE__, __LINE__);
@@ -4399,8 +4400,10 @@ _ssl__SSLContext_set_ecdh_curve(PySSLContext *self, PyObject *name)
     SSL_CTX_set_tmp_ecdh(self->ctx, key);
     EC_KEY_free(key);
 #else
-    if (!SSL_CTX_set1_groups(self->ctx, &nid, 1)) {
-        _setSSLError(get_state_ctx(self), NULL, 0, __FILE__, __LINE__);
+    int res = SSL_CTX_set1_groups_list(self->ctx, PyBytes_AS_STRING(name_bytes));
+    Py_DECREF(name_bytes);
+    if (!res) {
+        PyErr_Format(PyExc_ValueError,"unknown elliptic curves %R", name);
         return NULL;
     }
 #endif
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Adds support for multiple curves to be specified in SSLContext.set_ecdh_curve() for OpenSSL 3.0 and above by setting curve_name to a colon separated list of curves. This allows multiple curves to be passed on a TLS client hello.