diff --git a/test/smime-certs/mksmime-certs.sh b/test/smime-certs/mksmime-certs.sh
index 37c5633dc075eec04990a343d5472555ca0d7882..f01f66427c37411349d55ec14b0f672ae113f4a1 100644
--- a/test/smime-certs/mksmime-certs.sh
+++ b/test/smime-certs/mksmime-certs.sh
@@ -57,5 +57,18 @@ CN="Test S/MIME EE EC #2" $OPENSSL req -config ca.cnf -nodes \
 	-keyout smec2.pem -out req.pem -newkey ec:ecp2.pem
 $OPENSSL x509 -req -in req.pem -CA smroot.pem -days 3600 \
 	-extfile ca.cnf -extensions usr_cert -CAcreateserial >>smec2.pem
+# Create X9.42 DH parameters.
+$OPENSSL genpkey -genparam -algorithm DH -pkeyopt dh_paramgen_type:2 \
+	-out dhp.pem
+# Generate X9.42 DH key.
+$OPENSSL genpkey -paramfile dhp.pem -out smdh.pem
+$OPENSSL pkey -pubout -in smdh.pem -out dhpub.pem
+# Generate dummy request.
+CN="Test S/MIME EE DH #1" $OPENSSL req -config ca.cnf -nodes \
+	-keyout smtmp.pem -out req.pem -newkey rsa:2048
+# Sign request but force public key to DH
+$OPENSSL x509 -req -in req.pem -CA smroot.pem -days 3600 \
+	-force_pubkey dhpub.pem \
+	-extfile ca.cnf -extensions usr_cert -CAcreateserial >>smdh.pem
 # Remove temp files.
-rm -f req.pem ecp.pem ecp2.pem dsap.pem smroot.srl
+rm -f req.pem ecp.pem ecp2.pem dsap.pem dhp.pem dhpub.pem smtmp.pem smroot.srl
diff --git a/test/smime-certs/smdh.pem b/test/smime-certs/smdh.pem
new file mode 100644
index 0000000000000000000000000000000000000000..f831b0713b95889c2df8e50c369622a3fc6560be
--- /dev/null
+++ b/test/smime-certs/smdh.pem
@@ -0,0 +1,33 @@
+-----BEGIN PRIVATE KEY-----
+MIIBSgIBADCCASsGByqGSM4+AgEwggEeAoGBANQMSgwEcnEZ31kZxa9Ef8qOK/AJ
+9dMlsXMWVYnf/QevGdN/0Aei/j9a8QHG+CvvTm0DOEKhN9QUtABKsYZag865CA7B
+mSdHjQuFqILtzA25sDJ+3+jk9vbss+56ETRll/wasJVLGbmmHNkBMvc1fC1d/sGF
+cEn4zJnQvvFaeMgDAoGAaQD9ZvL8FYsJuNxN6qp5VfnfRqYvyi2PWSqtRKPGGC+V
+thYg49PRjwPOcXzvOsdEOQ7iH9jTiSvnUdwSSEwYTZkSBuQXAgOMJAWOpoXyaRvh
+atziBDoBnWS+/kX5RBhxvS0+em9yfRqAQleuGG+R1mEDihyJc8dWQQPT+O1l4oUC
+FQCJlKsQZ0VBrWPGcUCNa54ZW6TH9QQWAhRR2NMZrQSfWthXDO8Lj5WZ34zQrA==
+-----END PRIVATE KEY-----
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----