diff --git a/tests/data_files/dh.optlen.pem b/tests/data_files/dh.optlen.pem
new file mode 100644
index 0000000..ee1e29b
--- /dev/null
+++ b/tests/data_files/dh.optlen.pem
@@ -0,0 +1,58 @@
+
+Recommended key length: 256 bits
+
+generator:
+	80:0a:bf:e7:dc:66:7a:a1:7b:cd:7c:04:61:4b:c2:
+	21:a6:54:82:cc:c0:4b:60:46:02:b0:e1:31:90:8a:
+	93:8e:a1:1b:48:dc:51:5d:ab:7a:bc:bb:1e:0c:7f:
+	d6:65:11:ed:c0:d8:65:51:b7:63:24:96:e0:3d:f9:
+	43:57:e1:c4:ea:07:a7:ce:1e:38:1a:2f:ca:fd:ff:
+	5f:5b:f0:0d:f8:28:80:60:20:e8:75:c0:09:26:e4:
+	d0:11:f8:84:77:a1:b0:19:27:d7:38:13:ca:d4:84:
+	7c:63:96:b9:24:46:21:be:2b:00:b6:3c:65:92:53:
+	31:84:13:44:3c:d2:44:21:5c:d7:fd:4c:be:79:6e:
+	82:c6:cf:70:f8:9c:c0:c5:28:fb:8e:34:48:09:b3:
+	18:76:e7:ef:73:9d:51:60:d0:95:c9:68:41:88:b0:
+	c8:75:5c:7a:46:8d:47:f5:6d:6d:b9:ea:01:29:24:
+	ec:b0:55:6f:b7:13:12:a8:d7:c9:3b:b2:89:8e:a0:
+	8e:e5:4e:eb:59:45:48:28:5f:06:a9:73:cb:be:2a:
+	0c:b0:2e:90:f3:23:fe:04:55:21:f3:4c:68:35:4a:
+	6d:3e:95:db:ff:f1:eb:64:69:2e:dc:0a:44:f3:d3:
+	e4:08:d0:e4:79:a5:41:e7:79:a6:05:42:59:e2:d8:
+	54:
+
+prime:
+	b3:12:6a:ea:f4:71:53:c7:d6:7f:40:30:30:b2:92:
+	b5:bd:5a:6c:9e:ae:1c:13:7a:f3:40:87:fc:e2:a3:
+	6a:57:8d:70:c5:c5:60:ad:2b:db:92:4c:4a:4d:be:
+	e2:0a:16:71:be:71:03:ce:87:de:fa:76:90:89:36:
+	80:3d:be:ca:60:c3:3e:12:89:c1:a0:3a:c2:c6:c4:
+	e4:94:05:e5:90:2f:a0:59:6a:1c:ba:a8:95:cc:40:
+	2d:52:13:ed:4a:5f:1f:5b:a8:b5:e1:ed:3d:a9:51:
+	a4:c4:75:af:eb:0c:a6:60:b7:36:8c:38:c8:e8:09:
+	f3:82:d9:6a:e1:9e:60:dc:98:4e:61:cb:42:b5:df:
+	d7:23:32:2a:cf:32:7f:9e:41:3c:da:64:00:c1:5c:
+	5b:2e:a1:fa:34:40:5d:83:98:2f:ba:40:e6:d8:52:
+	da:3d:91:01:9b:f2:35:11:31:42:54:dc:21:1a:90:
+	83:3e:5b:17:98:ee:52:a7:81:98:c5:55:64:47:29:
+	ad:92:f0:60:36:7c:74:de:d3:77:04:ad:fc:27:3a:
+	4a:33:fe:c8:21:bd:2e:bd:3b:c0:51:73:0e:97:a4:
+	dd:14:d2:b7:66:06:25:92:f5:ee:c0:9d:16:bb:50:
+	ef:eb:f2:cc:00:dd:3e:0e:34:18:e6:0e:c8:48:70:
+	f7:
+
+
+-----BEGIN DH PARAMETERS-----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+-----END DH PARAMETERS-----