Add scripts to generate simple test data for certificate verification.

net/data/verify_certificate_chain_unittest/generate-target-wrong-signature.py

+#!/usr/bin/python
+# Copyright (c) 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Certificate chain where the target has an incorrect signature. Everything
+else should check out, however the digital signature contained in the target
+certificate is wrong."""
+
+import common
+
+# Self-signed root certificate (part of trust store).
+root = common.create_self_signed_root_certificate('Root')
+
+# Intermediary certificate to include in the certificate chain.
+intermediary = common.create_intermediary_certificate('Intermediary', root)
+
+# Actual intermediate that was used to sign the target certificate. It has the
+# same subject as expected, but a different RSA key from the certificate
+# included in the actual chain.
+wrong_intermediary = common.create_intermediary_certificate('Intermediary',
+                                                            root)
+
+# Target certificate, signed using |wrong_intermediary| NOT |intermediary|.
+target = common.create_end_entity_certificate('Target', wrong_intermediary)
+
+chain = [target, intermediary]
+trusted = [root]
+time = common.DEFAULT_TIME
+verify_result = False
+
+common.write_test_file(__doc__, chain, trusted, time, verify_result)