diff --git a/crypto/bytestring/cbb.c b/crypto/bytestring/cbb.c
index 850fa02..41770df 100644
--- a/crypto/bytestring/cbb.c
+++ b/crypto/bytestring/cbb.c
@@ -296,6 +296,14 @@
   return 1;
 }
 
+int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len) {
+  if (!CBB_flush(cbb) ||
+      !cbb_buffer_add(cbb->base, out_data, len)) {
+    return 0;
+  }
+  return 1;
+}
+
 int CBB_add_u8(CBB *cbb, uint8_t value) {
   if (!CBB_flush(cbb)) {
     return 0;
diff --git a/crypto/obj/obj.c b/crypto/obj/obj.c
index 624e731..6bbac92 100644
--- a/crypto/obj/obj.c
+++ b/crypto/obj/obj.c
@@ -301,6 +301,20 @@
   return nid;
 }
 
+OPENSSL_EXPORT int OBJ_nid2cbb(CBB *out, int nid) {
+  const ASN1_OBJECT *obj = OBJ_nid2obj(nid);
+  CBB oid;
+
+  if (obj == NULL ||
+      !CBB_add_asn1(out, &oid, CBS_ASN1_OBJECT) ||
+      !CBB_add_bytes(&oid, obj->data, obj->length) ||
+      !CBB_flush(out)) {
+    return 0;
+  }
+
+  return 1;
+}
+
 const ASN1_OBJECT *OBJ_nid2obj(int nid) {
   if (nid >= 0 && nid < NUM_NID) {
     if (nid != NID_undef && kObjects[nid].nid == NID_undef) {
diff --git a/crypto/x509/CMakeLists.txt b/crypto/x509/CMakeLists.txt
index 9017d76..08b7248 100644
--- a/crypto/x509/CMakeLists.txt
+++ b/crypto/x509/CMakeLists.txt
@@ -55,3 +55,11 @@
 	x_x509.c
 	x_x509a.c
 )
+
+add_executable(
+	pkcs7_test
+
+	pkcs7_test.c
+)
+
+target_link_libraries(pkcs7_test crypto)
diff --git a/crypto/x509/pkcs7.c b/crypto/x509/pkcs7.c
index 8bbb393..7744fcc 100644
--- a/crypto/x509/pkcs7.c
+++ b/crypto/x509/pkcs7.c
@@ -21,12 +21,12 @@
 
 
 int PKCS7_get_certificates(STACK_OF(X509) *out_certs, CBS *cbs) {
-  /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
   CBS content_info, content_type, wrapped_signed_data, signed_data,
       version_bytes, certificates;
   int nid;
   const size_t initial_certs_len = sk_X509_num(out_certs);
 
+  /* See https://tools.ietf.org/html/rfc2315#section-7 */
   if (!CBS_get_asn1_ber(cbs, &content_info, CBS_ASN1_SEQUENCE) ||
       !CBS_get_asn1(&content_info, &content_type, CBS_ASN1_OBJECT)) {
     return 0;
@@ -39,6 +39,7 @@
     return 0;
   }
 
+  /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
   if (!CBS_get_asn1_ber(&content_info, &wrapped_signed_data,
                         CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0) ||
       !CBS_get_asn1_ber(&wrapped_signed_data, &signed_data,
@@ -95,3 +96,40 @@
 
   return 0;
 }
+
+int PKCS7_bundle_certificates(CBB *out, const STACK_OF(X509) *certs) {
+  CBB outer_seq, wrapped_seq, seq, version_bytes, digest_algos_set,
+      content_info, certificates;
+  size_t i;
+
+  /* See https://tools.ietf.org/html/rfc2315#section-7 */
+  if (!CBB_add_asn1(out, &outer_seq, CBS_ASN1_SEQUENCE) ||
+      !OBJ_nid2cbb(&outer_seq, NID_pkcs7_signed) ||
+      !CBB_add_asn1(&outer_seq, &wrapped_seq,
+                    CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0) ||
+      /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
+      !CBB_add_asn1(&wrapped_seq, &seq, CBS_ASN1_SEQUENCE) ||
+      !CBB_add_asn1(&seq, &version_bytes, CBS_ASN1_INTEGER) ||
+      !CBB_add_u8(&version_bytes, 1) ||
+      !CBB_add_asn1(&seq, &digest_algos_set, CBS_ASN1_SET) ||
+      !CBB_add_asn1(&seq, &content_info, CBS_ASN1_SEQUENCE) ||
+      !OBJ_nid2cbb(&content_info, NID_pkcs7_data) ||
+      !CBB_add_asn1(&seq, &certificates,
+                    CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0)) {
+    return 0;
+  }
+
+  for (i = 0; i < sk_X509_num(certs); i++) {
+    X509 *x509 = sk_X509_value(certs, i);
+    uint8_t *buf;
+    int len = i2d_X509(x509, NULL);
+
+    if (len < 0 ||
+        !CBB_add_space(&certificates, &buf, len) ||
+        i2d_X509(x509, &buf) < 0) {
+      return 0;
+    }
+  }
+
+  return CBB_flush(out);
+}
diff --git a/crypto/x509/pkcs7_test.c b/crypto/x509/pkcs7_test.c
new file mode 100644
index 0000000..eb2668f
--- /dev/null
+++ b/crypto/x509/pkcs7_test.c
@@ -0,0 +1,342 @@
+/* Copyright (c) 2014, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <openssl/bytestring.h>
+#include <openssl/stack.h>
+#include <openssl/x509.h>
+
+
+/* kPKCS7DER contains the certificate chain of mail.google.com, as saved by NSS
+ * using the Chrome UI. */
+static const uint8_t kPKCS7DER[] = {
+    0x30, 0x80, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x07,
+    0x02, 0xa0, 0x80, 0x30, 0x80, 0x02, 0x01, 0x01, 0x31, 0x00, 0x30, 0x80,
+    0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x07, 0x01, 0x00,
+    0x00, 0xa0, 0x82, 0x0b, 0x1e, 0x30, 0x82, 0x03, 0x54, 0x30, 0x82, 0x02,
+    0x3c, 0xa0, 0x03, 0x02, 0x01, 0x02, 0x02, 0x03, 0x02, 0x34, 0x56, 0x30,
+    0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x05,
+    0x05, 0x00, 0x30, 0x42, 0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04,
+    0x06, 0x13, 0x02, 0x55, 0x53, 0x31, 0x16, 0x30, 0x14, 0x06, 0x03, 0x55,
+    0x04, 0x0a, 0x13, 0x0d, 0x47, 0x65, 0x6f, 0x54, 0x72, 0x75, 0x73, 0x74,
+    0x20, 0x49, 0x6e, 0x63, 0x2e, 0x31, 0x1b, 0x30, 0x19, 0x06, 0x03, 0x55,
+    0x04, 0x03, 0x13, 0x12, 0x47, 0x65, 0x6f, 0x54, 0x72, 0x75, 0x73, 0x74,
+    0x20, 0x47, 0x6c, 0x6f, 0x62, 0x61, 0x6c, 0x20, 0x43, 0x41, 0x30, 0x1e,
+    0x17, 0x0d, 0x30, 0x32, 0x30, 0x35, 0x32, 0x31, 0x30, 0x34, 0x30, 0x30,
+    0x30, 0x30, 0x5a, 0x17, 0x0d, 0x32, 0x32, 0x30, 0x35, 0x32, 0x31, 0x30,
+    0x34, 0x30, 0x30, 0x30, 0x30, 0x5a, 0x30, 0x42, 0x31, 0x0b, 0x30, 0x09,
+    0x06, 0x03, 0x55, 0x04, 0x06, 0x13, 0x02, 0x55, 0x53, 0x31, 0x16, 0x30,
+    0x14, 0x06, 0x03, 0x55, 0x04, 0x0a, 0x13, 0x0d, 0x47, 0x65, 0x6f, 0x54,
+    0x72, 0x75, 0x73, 0x74, 0x20, 0x49, 0x6e, 0x63, 0x2e, 0x31, 0x1b, 0x30,
+    0x19, 0x06, 0x03, 0x55, 0x04, 0x03, 0x13, 0x12, 0x47, 0x65, 0x6f, 0x54,
+    0x72, 0x75, 0x73, 0x74, 0x20, 0x47, 0x6c, 0x6f, 0x62, 0x61, 0x6c, 0x20,
+    0x43, 0x41, 0x30, 0x82, 0x01, 0x22, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86,
+    0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 0x03, 0x82, 0x01,
+    0x0f, 0x00, 0x30, 0x82, 0x01, 0x0a, 0x02, 0x82, 0x01, 0x01, 0x00, 0xda,
+    0xcc, 0x18, 0x63, 0x30, 0xfd, 0xf4, 0x17, 0x23, 0x1a, 0x56, 0x7e, 0x5b,
+    0xdf, 0x3c, 0x6c, 0x38, 0xe4, 0x71, 0xb7, 0x78, 0x91, 0xd4, 0xbc, 0xa1,
+    0xd8, 0x4c, 0xf8, 0xa8, 0x43, 0xb6, 0x03, 0xe9, 0x4d, 0x21, 0x07, 0x08,
+    0x88, 0xda, 0x58, 0x2f, 0x66, 0x39, 0x29, 0xbd, 0x05, 0x78, 0x8b, 0x9d,
+    0x38, 0xe8, 0x05, 0xb7, 0x6a, 0x7e, 0x71, 0xa4, 0xe6, 0xc4, 0x60, 0xa6,
+    0xb0, 0xef, 0x80, 0xe4, 0x89, 0x28, 0x0f, 0x9e, 0x25, 0xd6, 0xed, 0x83,
+    0xf3, 0xad, 0xa6, 0x91, 0xc7, 0x98, 0xc9, 0x42, 0x18, 0x35, 0x14, 0x9d,
+    0xad, 0x98, 0x46, 0x92, 0x2e, 0x4f, 0xca, 0xf1, 0x87, 0x43, 0xc1, 0x16,
+    0x95, 0x57, 0x2d, 0x50, 0xef, 0x89, 0x2d, 0x80, 0x7a, 0x57, 0xad, 0xf2,
+    0xee, 0x5f, 0x6b, 0xd2, 0x00, 0x8d, 0xb9, 0x14, 0xf8, 0x14, 0x15, 0x35,
+    0xd9, 0xc0, 0x46, 0xa3, 0x7b, 0x72, 0xc8, 0x91, 0xbf, 0xc9, 0x55, 0x2b,
+    0xcd, 0xd0, 0x97, 0x3e, 0x9c, 0x26, 0x64, 0xcc, 0xdf, 0xce, 0x83, 0x19,
+    0x71, 0xca, 0x4e, 0xe6, 0xd4, 0xd5, 0x7b, 0xa9, 0x19, 0xcd, 0x55, 0xde,
+    0xc8, 0xec, 0xd2, 0x5e, 0x38, 0x53, 0xe5, 0x5c, 0x4f, 0x8c, 0x2d, 0xfe,
+    0x50, 0x23, 0x36, 0xfc, 0x66, 0xe6, 0xcb, 0x8e, 0xa4, 0x39, 0x19, 0x00,
+    0xb7, 0x95, 0x02, 0x39, 0x91, 0x0b, 0x0e, 0xfe, 0x38, 0x2e, 0xd1, 0x1d,
+    0x05, 0x9a, 0xf6, 0x4d, 0x3e, 0x6f, 0x0f, 0x07, 0x1d, 0xaf, 0x2c, 0x1e,
+    0x8f, 0x60, 0x39, 0xe2, 0xfa, 0x36, 0x53, 0x13, 0x39, 0xd4, 0x5e, 0x26,
+    0x2b, 0xdb, 0x3d, 0xa8, 0x14, 0xbd, 0x32, 0xeb, 0x18, 0x03, 0x28, 0x52,
+    0x04, 0x71, 0xe5, 0xab, 0x33, 0x3d, 0xe1, 0x38, 0xbb, 0x07, 0x36, 0x84,
+    0x62, 0x9c, 0x79, 0xea, 0x16, 0x30, 0xf4, 0x5f, 0xc0, 0x2b, 0xe8, 0x71,
+    0x6b, 0xe4, 0xf9, 0x02, 0x03, 0x01, 0x00, 0x01, 0xa3, 0x53, 0x30, 0x51,
+    0x30, 0x0f, 0x06, 0x03, 0x55, 0x1d, 0x13, 0x01, 0x01, 0xff, 0x04, 0x05,
+    0x30, 0x03, 0x01, 0x01, 0xff, 0x30, 0x1d, 0x06, 0x03, 0x55, 0x1d, 0x0e,
+    0x04, 0x16, 0x04, 0x14, 0xc0, 0x7a, 0x98, 0x68, 0x8d, 0x89, 0xfb, 0xab,
+    0x05, 0x64, 0x0c, 0x11, 0x7d, 0xaa, 0x7d, 0x65, 0xb8, 0xca, 0xcc, 0x4e,
+    0x30, 0x1f, 0x06, 0x03, 0x55, 0x1d, 0x23, 0x04, 0x18, 0x30, 0x16, 0x80,
+    0x14, 0xc0, 0x7a, 0x98, 0x68, 0x8d, 0x89, 0xfb, 0xab, 0x05, 0x64, 0x0c,
+    0x11, 0x7d, 0xaa, 0x7d, 0x65, 0xb8, 0xca, 0xcc, 0x4e, 0x30, 0x0d, 0x06,
+    0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x05, 0x05, 0x00,
+    0x03, 0x82, 0x01, 0x01, 0x00, 0x35, 0xe3, 0x29, 0x6a, 0xe5, 0x2f, 0x5d,
+    0x54, 0x8e, 0x29, 0x50, 0x94, 0x9f, 0x99, 0x1a, 0x14, 0xe4, 0x8f, 0x78,
+    0x2a, 0x62, 0x94, 0xa2, 0x27, 0x67, 0x9e, 0xd0, 0xcf, 0x1a, 0x5e, 0x47,
+    0xe9, 0xc1, 0xb2, 0xa4, 0xcf, 0xdd, 0x41, 0x1a, 0x05, 0x4e, 0x9b, 0x4b,
+    0xee, 0x4a, 0x6f, 0x55, 0x52, 0xb3, 0x24, 0xa1, 0x37, 0x0a, 0xeb, 0x64,
+    0x76, 0x2a, 0x2e, 0x2c, 0xf3, 0xfd, 0x3b, 0x75, 0x90, 0xbf, 0xfa, 0x71,
+    0xd8, 0xc7, 0x3d, 0x37, 0xd2, 0xb5, 0x05, 0x95, 0x62, 0xb9, 0xa6, 0xde,
+    0x89, 0x3d, 0x36, 0x7b, 0x38, 0x77, 0x48, 0x97, 0xac, 0xa6, 0x20, 0x8f,
+    0x2e, 0xa6, 0xc9, 0x0c, 0xc2, 0xb2, 0x99, 0x45, 0x00, 0xc7, 0xce, 0x11,
+    0x51, 0x22, 0x22, 0xe0, 0xa5, 0xea, 0xb6, 0x15, 0x48, 0x09, 0x64, 0xea,
+    0x5e, 0x4f, 0x74, 0xf7, 0x05, 0x3e, 0xc7, 0x8a, 0x52, 0x0c, 0xdb, 0x15,
+    0xb4, 0xbd, 0x6d, 0x9b, 0xe5, 0xc6, 0xb1, 0x54, 0x68, 0xa9, 0xe3, 0x69,
+    0x90, 0xb6, 0x9a, 0xa5, 0x0f, 0xb8, 0xb9, 0x3f, 0x20, 0x7d, 0xae, 0x4a,
+    0xb5, 0xb8, 0x9c, 0xe4, 0x1d, 0xb6, 0xab, 0xe6, 0x94, 0xa5, 0xc1, 0xc7,
+    0x83, 0xad, 0xdb, 0xf5, 0x27, 0x87, 0x0e, 0x04, 0x6c, 0xd5, 0xff, 0xdd,
+    0xa0, 0x5d, 0xed, 0x87, 0x52, 0xb7, 0x2b, 0x15, 0x02, 0xae, 0x39, 0xa6,
+    0x6a, 0x74, 0xe9, 0xda, 0xc4, 0xe7, 0xbc, 0x4d, 0x34, 0x1e, 0xa9, 0x5c,
+    0x4d, 0x33, 0x5f, 0x92, 0x09, 0x2f, 0x88, 0x66, 0x5d, 0x77, 0x97, 0xc7,
+    0x1d, 0x76, 0x13, 0xa9, 0xd5, 0xe5, 0xf1, 0x16, 0x09, 0x11, 0x35, 0xd5,
+    0xac, 0xdb, 0x24, 0x71, 0x70, 0x2c, 0x98, 0x56, 0x0b, 0xd9, 0x17, 0xb4,
+    0xd1, 0xe3, 0x51, 0x2b, 0x5e, 0x75, 0xe8, 0xd5, 0xd0, 0xdc, 0x4f, 0x34,
+    0xed, 0xc2, 0x05, 0x66, 0x80, 0xa1, 0xcb, 0xe6, 0x33, 0x30, 0x82, 0x03,
+    0xba, 0x30, 0x82, 0x02, 0xa2, 0xa0, 0x03, 0x02, 0x01, 0x02, 0x02, 0x08,
+    0x3e, 0xa3, 0xe4, 0x78, 0x99, 0x38, 0x13, 0x9d, 0x30, 0x0d, 0x06, 0x09,
+    0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x05, 0x05, 0x00, 0x30,
+    0x49, 0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04, 0x06, 0x13, 0x02,
+    0x55, 0x53, 0x31, 0x13, 0x30, 0x11, 0x06, 0x03, 0x55, 0x04, 0x0a, 0x13,
+    0x0a, 0x47, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x20, 0x49, 0x6e, 0x63, 0x31,
+    0x25, 0x30, 0x23, 0x06, 0x03, 0x55, 0x04, 0x03, 0x13, 0x1c, 0x47, 0x6f,
+    0x6f, 0x67, 0x6c, 0x65, 0x20, 0x49, 0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65,
+    0x74, 0x20, 0x41, 0x75, 0x74, 0x68, 0x6f, 0x72, 0x69, 0x74, 0x79, 0x20,
+    0x47, 0x32, 0x30, 0x1e, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x37, 0x31, 0x36,
+    0x31, 0x32, 0x32, 0x31, 0x34, 0x30, 0x5a, 0x17, 0x0d, 0x31, 0x34, 0x31,
+    0x30, 0x31, 0x34, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x5a, 0x30, 0x69,
+    0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04, 0x06, 0x13, 0x02, 0x55,
+    0x53, 0x31, 0x13, 0x30, 0x11, 0x06, 0x03, 0x55, 0x04, 0x08, 0x0c, 0x0a,
+    0x43, 0x61, 0x6c, 0x69, 0x66, 0x6f, 0x72, 0x6e, 0x69, 0x61, 0x31, 0x16,
+    0x30, 0x14, 0x06, 0x03, 0x55, 0x04, 0x07, 0x0c, 0x0d, 0x4d, 0x6f, 0x75,
+    0x6e, 0x74, 0x61, 0x69, 0x6e, 0x20, 0x56, 0x69, 0x65, 0x77, 0x31, 0x13,
+    0x30, 0x11, 0x06, 0x03, 0x55, 0x04, 0x0a, 0x0c, 0x0a, 0x47, 0x6f, 0x6f,
+    0x67, 0x6c, 0x65, 0x20, 0x49, 0x6e, 0x63, 0x31, 0x18, 0x30, 0x16, 0x06,
+    0x03, 0x55, 0x04, 0x03, 0x0c, 0x0f, 0x6d, 0x61, 0x69, 0x6c, 0x2e, 0x67,
+    0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e, 0x63, 0x6f, 0x6d, 0x30, 0x59, 0x30,
+    0x13, 0x06, 0x07, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08,
+    0x2a, 0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0x03, 0x42, 0x00, 0x04,
+    0xb2, 0x68, 0x6e, 0x3f, 0x03, 0x9e, 0x43, 0x85, 0x16, 0xb7, 0x89, 0x0b,
+    0x16, 0x2a, 0xbe, 0x26, 0x36, 0xdd, 0x68, 0x0a, 0x53, 0x4e, 0x20, 0x40,
+    0xf8, 0xd1, 0xdd, 0x63, 0xcb, 0x46, 0x73, 0x09, 0x96, 0x36, 0xde, 0x2c,
+    0x45, 0x71, 0x2e, 0x8a, 0x79, 0xeb, 0x40, 0x2f, 0x65, 0x83, 0x81, 0xdb,
+    0x37, 0x03, 0x84, 0xa1, 0x9a, 0xd0, 0x22, 0x3b, 0x73, 0x38, 0x45, 0xd3,
+    0xd5, 0x91, 0xb2, 0x52, 0xa3, 0x82, 0x01, 0x4f, 0x30, 0x82, 0x01, 0x4b,
+    0x30, 0x1d, 0x06, 0x03, 0x55, 0x1d, 0x25, 0x04, 0x16, 0x30, 0x14, 0x06,
+    0x08, 0x2b, 0x06, 0x01, 0x05, 0x05, 0x07, 0x03, 0x01, 0x06, 0x08, 0x2b,
+    0x06, 0x01, 0x05, 0x05, 0x07, 0x03, 0x02, 0x30, 0x1a, 0x06, 0x03, 0x55,
+    0x1d, 0x11, 0x04, 0x13, 0x30, 0x11, 0x82, 0x0f, 0x6d, 0x61, 0x69, 0x6c,
+    0x2e, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e, 0x63, 0x6f, 0x6d, 0x30,
+    0x0b, 0x06, 0x03, 0x55, 0x1d, 0x0f, 0x04, 0x04, 0x03, 0x02, 0x07, 0x80,
+    0x30, 0x68, 0x06, 0x08, 0x2b, 0x06, 0x01, 0x05, 0x05, 0x07, 0x01, 0x01,
+    0x04, 0x5c, 0x30, 0x5a, 0x30, 0x2b, 0x06, 0x08, 0x2b, 0x06, 0x01, 0x05,
+    0x05, 0x07, 0x30, 0x02, 0x86, 0x1f, 0x68, 0x74, 0x74, 0x70, 0x3a, 0x2f,
+    0x2f, 0x70, 0x6b, 0x69, 0x2e, 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e,
+    0x63, 0x6f, 0x6d, 0x2f, 0x47, 0x49, 0x41, 0x47, 0x32, 0x2e, 0x63, 0x72,
+    0x74, 0x30, 0x2b, 0x06, 0x08, 0x2b, 0x06, 0x01, 0x05, 0x05, 0x07, 0x30,
+    0x01, 0x86, 0x1f, 0x68, 0x74, 0x74, 0x70, 0x3a, 0x2f, 0x2f, 0x63, 0x6c,
+    0x69, 0x65, 0x6e, 0x74, 0x73, 0x31, 0x2e, 0x67, 0x6f, 0x6f, 0x67, 0x6c,
+    0x65, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x6f, 0x63, 0x73, 0x70, 0x30, 0x1d,
+    0x06, 0x03, 0x55, 0x1d, 0x0e, 0x04, 0x16, 0x04, 0x14, 0x75, 0xc6, 0xb0,
+    0x4a, 0x46, 0x61, 0x83, 0xff, 0x91, 0x46, 0x45, 0x35, 0xa7, 0x0f, 0xd0,
+    0x5b, 0xe9, 0xdd, 0x94, 0x1b, 0x30, 0x0c, 0x06, 0x03, 0x55, 0x1d, 0x13,
+    0x01, 0x01, 0xff, 0x04, 0x02, 0x30, 0x00, 0x30, 0x1f, 0x06, 0x03, 0x55,
+    0x1d, 0x23, 0x04, 0x18, 0x30, 0x16, 0x80, 0x14, 0x4a, 0xdd, 0x06, 0x16,
+    0x1b, 0xbc, 0xf6, 0x68, 0xb5, 0x76, 0xf5, 0x81, 0xb6, 0xbb, 0x62, 0x1a,
+    0xba, 0x5a, 0x81, 0x2f, 0x30, 0x17, 0x06, 0x03, 0x55, 0x1d, 0x20, 0x04,
+    0x10, 0x30, 0x0e, 0x30, 0x0c, 0x06, 0x0a, 0x2b, 0x06, 0x01, 0x04, 0x01,
+    0xd6, 0x79, 0x02, 0x05, 0x01, 0x30, 0x30, 0x06, 0x03, 0x55, 0x1d, 0x1f,
+    0x04, 0x29, 0x30, 0x27, 0x30, 0x25, 0xa0, 0x23, 0xa0, 0x21, 0x86, 0x1f,
+    0x68, 0x74, 0x74, 0x70, 0x3a, 0x2f, 0x2f, 0x70, 0x6b, 0x69, 0x2e, 0x67,
+    0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x47, 0x49,
+    0x41, 0x47, 0x32, 0x2e, 0x63, 0x72, 0x6c, 0x30, 0x0d, 0x06, 0x09, 0x2a,
+    0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x05, 0x05, 0x00, 0x03, 0x82,
+    0x01, 0x01, 0x00, 0x7f, 0x41, 0xf5, 0x57, 0x18, 0x3c, 0x75, 0xf5, 0x23,
+    0x66, 0xc3, 0xf0, 0xf2, 0x3e, 0x70, 0x34, 0x56, 0xca, 0x78, 0xec, 0xc7,
+    0x81, 0x58, 0x0d, 0xdf, 0xf0, 0xfd, 0x86, 0xe6, 0xe6, 0x50, 0x3d, 0xf6,
+    0x09, 0x9a, 0x4d, 0xca, 0x60, 0x37, 0x9a, 0xd4, 0xca, 0x51, 0x7c, 0xf0,
+    0x66, 0x23, 0xea, 0x5e, 0x6a, 0x6f, 0x7b, 0xa6, 0x7a, 0x38, 0x97, 0x42,
+    0x58, 0x1a, 0x1b, 0x42, 0xae, 0x28, 0xde, 0x18, 0x7f, 0xcc, 0x76, 0x18,
+    0x58, 0x05, 0xbf, 0xea, 0xef, 0x14, 0xad, 0x34, 0xe5, 0x5f, 0x25, 0xab,
+    0xa1, 0x5f, 0x78, 0x5b, 0x6f, 0xe6, 0x69, 0xd8, 0x74, 0x8c, 0x19, 0x59,
+    0xb0, 0x1a, 0xfb, 0x8e, 0xdf, 0x61, 0xac, 0xeb, 0x2b, 0x0a, 0x1c, 0xab,
+    0x30, 0x0d, 0x64, 0x25, 0x78, 0xdf, 0x81, 0x71, 0xe3, 0xbd, 0xde, 0x9c,
+    0x3f, 0xdd, 0xe9, 0xf8, 0xb6, 0x98, 0x2d, 0x13, 0xa3, 0x7b, 0x14, 0x6f,
+    0xe3, 0x8b, 0xfc, 0x4e, 0x31, 0x26, 0xba, 0x10, 0xb4, 0x12, 0xe9, 0xc9,
+    0x49, 0x60, 0xf0, 0xaa, 0x1f, 0x44, 0x68, 0x19, 0xd2, 0xb3, 0xc8, 0x46,
+    0x22, 0x6b, 0xe1, 0x21, 0x77, 0xfd, 0x72, 0x33, 0x13, 0x21, 0x27, 0x81,
+    0xe4, 0x7a, 0xc9, 0xe4, 0x1c, 0x05, 0x04, 0x73, 0x13, 0xda, 0x47, 0xfe,
+    0x59, 0x41, 0x9c, 0x11, 0xc5, 0xf6, 0xb5, 0xd0, 0x01, 0xcb, 0x40, 0x19,
+    0xf5, 0xfe, 0xb3, 0x3c, 0x1f, 0x61, 0x8f, 0x4d, 0xdb, 0x81, 0x2a, 0x8a,
+    0xed, 0xb8, 0x53, 0xc7, 0x19, 0x6b, 0xfa, 0x8b, 0xfc, 0xe3, 0x2e, 0x12,
+    0x4e, 0xbd, 0xc5, 0x44, 0x9d, 0x1c, 0x7f, 0x3b, 0x09, 0x51, 0xd7, 0x0a,
+    0x0f, 0x22, 0x0a, 0xfd, 0x8c, 0x90, 0x14, 0xed, 0x10, 0xcb, 0x50, 0xcf,
+    0xa5, 0x45, 0xce, 0xb0, 0x21, 0x28, 0xcb, 0xd6, 0xf5, 0x6e, 0xb2, 0x3e,
+    0xfa, 0x35, 0x0c, 0x3d, 0x09, 0x0d, 0x81, 0x30, 0x82, 0x04, 0x04, 0x30,
+    0x82, 0x02, 0xec, 0xa0, 0x03, 0x02, 0x01, 0x02, 0x02, 0x03, 0x02, 0x3a,
+    0x69, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01,
+    0x01, 0x05, 0x05, 0x00, 0x30, 0x42, 0x31, 0x0b, 0x30, 0x09, 0x06, 0x03,
+    0x55, 0x04, 0x06, 0x13, 0x02, 0x55, 0x53, 0x31, 0x16, 0x30, 0x14, 0x06,
+    0x03, 0x55, 0x04, 0x0a, 0x13, 0x0d, 0x47, 0x65, 0x6f, 0x54, 0x72, 0x75,
+    0x73, 0x74, 0x20, 0x49, 0x6e, 0x63, 0x2e, 0x31, 0x1b, 0x30, 0x19, 0x06,
+    0x03, 0x55, 0x04, 0x03, 0x13, 0x12, 0x47, 0x65, 0x6f, 0x54, 0x72, 0x75,
+    0x73, 0x74, 0x20, 0x47, 0x6c, 0x6f, 0x62, 0x61, 0x6c, 0x20, 0x43, 0x41,
+    0x30, 0x1e, 0x17, 0x0d, 0x31, 0x33, 0x30, 0x34, 0x30, 0x35, 0x31, 0x35,
+    0x31, 0x35, 0x35, 0x35, 0x5a, 0x17, 0x0d, 0x31, 0x35, 0x30, 0x34, 0x30,
+    0x34, 0x31, 0x35, 0x31, 0x35, 0x35, 0x35, 0x5a, 0x30, 0x49, 0x31, 0x0b,
+    0x30, 0x09, 0x06, 0x03, 0x55, 0x04, 0x06, 0x13, 0x02, 0x55, 0x53, 0x31,
+    0x13, 0x30, 0x11, 0x06, 0x03, 0x55, 0x04, 0x0a, 0x13, 0x0a, 0x47, 0x6f,
+    0x6f, 0x67, 0x6c, 0x65, 0x20, 0x49, 0x6e, 0x63, 0x31, 0x25, 0x30, 0x23,
+    0x06, 0x03, 0x55, 0x04, 0x03, 0x13, 0x1c, 0x47, 0x6f, 0x6f, 0x67, 0x6c,
+    0x65, 0x20, 0x49, 0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65, 0x74, 0x20, 0x41,
+    0x75, 0x74, 0x68, 0x6f, 0x72, 0x69, 0x74, 0x79, 0x20, 0x47, 0x32, 0x30,
+    0x82, 0x01, 0x22, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7,
+    0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 0x03, 0x82, 0x01, 0x0f, 0x00, 0x30,
+    0x82, 0x01, 0x0a, 0x02, 0x82, 0x01, 0x01, 0x00, 0x9c, 0x2a, 0x04, 0x77,
+    0x5c, 0xd8, 0x50, 0x91, 0x3a, 0x06, 0xa3, 0x82, 0xe0, 0xd8, 0x50, 0x48,
+    0xbc, 0x89, 0x3f, 0xf1, 0x19, 0x70, 0x1a, 0x88, 0x46, 0x7e, 0xe0, 0x8f,
+    0xc5, 0xf1, 0x89, 0xce, 0x21, 0xee, 0x5a, 0xfe, 0x61, 0x0d, 0xb7, 0x32,
+    0x44, 0x89, 0xa0, 0x74, 0x0b, 0x53, 0x4f, 0x55, 0xa4, 0xce, 0x82, 0x62,
+    0x95, 0xee, 0xeb, 0x59, 0x5f, 0xc6, 0xe1, 0x05, 0x80, 0x12, 0xc4, 0x5e,
+    0x94, 0x3f, 0xbc, 0x5b, 0x48, 0x38, 0xf4, 0x53, 0xf7, 0x24, 0xe6, 0xfb,
+    0x91, 0xe9, 0x15, 0xc4, 0xcf, 0xf4, 0x53, 0x0d, 0xf4, 0x4a, 0xfc, 0x9f,
+    0x54, 0xde, 0x7d, 0xbe, 0xa0, 0x6b, 0x6f, 0x87, 0xc0, 0xd0, 0x50, 0x1f,
+    0x28, 0x30, 0x03, 0x40, 0xda, 0x08, 0x73, 0x51, 0x6c, 0x7f, 0xff, 0x3a,
+    0x3c, 0xa7, 0x37, 0x06, 0x8e, 0xbd, 0x4b, 0x11, 0x04, 0xeb, 0x7d, 0x24,
+    0xde, 0xe6, 0xf9, 0xfc, 0x31, 0x71, 0xfb, 0x94, 0xd5, 0x60, 0xf3, 0x2e,
+    0x4a, 0xaf, 0x42, 0xd2, 0xcb, 0xea, 0xc4, 0x6a, 0x1a, 0xb2, 0xcc, 0x53,
+    0xdd, 0x15, 0x4b, 0x8b, 0x1f, 0xc8, 0x19, 0x61, 0x1f, 0xcd, 0x9d, 0xa8,
+    0x3e, 0x63, 0x2b, 0x84, 0x35, 0x69, 0x65, 0x84, 0xc8, 0x19, 0xc5, 0x46,
+    0x22, 0xf8, 0x53, 0x95, 0xbe, 0xe3, 0x80, 0x4a, 0x10, 0xc6, 0x2a, 0xec,
+    0xba, 0x97, 0x20, 0x11, 0xc7, 0x39, 0x99, 0x10, 0x04, 0xa0, 0xf0, 0x61,
+    0x7a, 0x95, 0x25, 0x8c, 0x4e, 0x52, 0x75, 0xe2, 0xb6, 0xed, 0x08, 0xca,
+    0x14, 0xfc, 0xce, 0x22, 0x6a, 0xb3, 0x4e, 0xcf, 0x46, 0x03, 0x97, 0x97,
+    0x03, 0x7e, 0xc0, 0xb1, 0xde, 0x7b, 0xaf, 0x45, 0x33, 0xcf, 0xba, 0x3e,
+    0x71, 0xb7, 0xde, 0xf4, 0x25, 0x25, 0xc2, 0x0d, 0x35, 0x89, 0x9d, 0x9d,
+    0xfb, 0x0e, 0x11, 0x79, 0x89, 0x1e, 0x37, 0xc5, 0xaf, 0x8e, 0x72, 0x69,
+    0x02, 0x03, 0x01, 0x00, 0x01, 0xa3, 0x81, 0xfb, 0x30, 0x81, 0xf8, 0x30,
+    0x1f, 0x06, 0x03, 0x55, 0x1d, 0x23, 0x04, 0x18, 0x30, 0x16, 0x80, 0x14,
+    0xc0, 0x7a, 0x98, 0x68, 0x8d, 0x89, 0xfb, 0xab, 0x05, 0x64, 0x0c, 0x11,
+    0x7d, 0xaa, 0x7d, 0x65, 0xb8, 0xca, 0xcc, 0x4e, 0x30, 0x1d, 0x06, 0x03,
+    0x55, 0x1d, 0x0e, 0x04, 0x16, 0x04, 0x14, 0x4a, 0xdd, 0x06, 0x16, 0x1b,
+    0xbc, 0xf6, 0x68, 0xb5, 0x76, 0xf5, 0x81, 0xb6, 0xbb, 0x62, 0x1a, 0xba,
+    0x5a, 0x81, 0x2f, 0x30, 0x12, 0x06, 0x03, 0x55, 0x1d, 0x13, 0x01, 0x01,
+    0xff, 0x04, 0x08, 0x30, 0x06, 0x01, 0x01, 0xff, 0x02, 0x01, 0x00, 0x30,
+    0x0e, 0x06, 0x03, 0x55, 0x1d, 0x0f, 0x01, 0x01, 0xff, 0x04, 0x04, 0x03,
+    0x02, 0x01, 0x06, 0x30, 0x3a, 0x06, 0x03, 0x55, 0x1d, 0x1f, 0x04, 0x33,
+    0x30, 0x31, 0x30, 0x2f, 0xa0, 0x2d, 0xa0, 0x2b, 0x86, 0x29, 0x68, 0x74,
+    0x74, 0x70, 0x3a, 0x2f, 0x2f, 0x63, 0x72, 0x6c, 0x2e, 0x67, 0x65, 0x6f,
+    0x74, 0x72, 0x75, 0x73, 0x74, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x63, 0x72,
+    0x6c, 0x73, 0x2f, 0x67, 0x74, 0x67, 0x6c, 0x6f, 0x62, 0x61, 0x6c, 0x2e,
+    0x63, 0x72, 0x6c, 0x30, 0x3d, 0x06, 0x08, 0x2b, 0x06, 0x01, 0x05, 0x05,
+    0x07, 0x01, 0x01, 0x04, 0x31, 0x30, 0x2f, 0x30, 0x2d, 0x06, 0x08, 0x2b,
+    0x06, 0x01, 0x05, 0x05, 0x07, 0x30, 0x01, 0x86, 0x21, 0x68, 0x74, 0x74,
+    0x70, 0x3a, 0x2f, 0x2f, 0x67, 0x74, 0x67, 0x6c, 0x6f, 0x62, 0x61, 0x6c,
+    0x2d, 0x6f, 0x63, 0x73, 0x70, 0x2e, 0x67, 0x65, 0x6f, 0x74, 0x72, 0x75,
+    0x73, 0x74, 0x2e, 0x63, 0x6f, 0x6d, 0x30, 0x17, 0x06, 0x03, 0x55, 0x1d,
+    0x20, 0x04, 0x10, 0x30, 0x0e, 0x30, 0x0c, 0x06, 0x0a, 0x2b, 0x06, 0x01,
+    0x04, 0x01, 0xd6, 0x79, 0x02, 0x05, 0x01, 0x30, 0x0d, 0x06, 0x09, 0x2a,
+    0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x05, 0x05, 0x00, 0x03, 0x82,
+    0x01, 0x01, 0x00, 0x36, 0xd7, 0x06, 0x80, 0x11, 0x27, 0xad, 0x2a, 0x14,
+    0x9b, 0x38, 0x77, 0xb3, 0x23, 0xa0, 0x75, 0x58, 0xbb, 0xb1, 0x7e, 0x83,
+    0x42, 0xba, 0x72, 0xda, 0x1e, 0xd8, 0x8e, 0x36, 0x06, 0x97, 0xe0, 0xf0,
+    0x95, 0x3b, 0x37, 0xfd, 0x1b, 0x42, 0x58, 0xfe, 0x22, 0xc8, 0x6b, 0xbd,
+    0x38, 0x5e, 0xd1, 0x3b, 0x25, 0x6e, 0x12, 0xeb, 0x5e, 0x67, 0x76, 0x46,
+    0x40, 0x90, 0xda, 0x14, 0xc8, 0x78, 0x0d, 0xed, 0x95, 0x66, 0xda, 0x8e,
+    0x86, 0x6f, 0x80, 0xa1, 0xba, 0x56, 0x32, 0x95, 0x86, 0xdc, 0xdc, 0x6a,
+    0xca, 0x04, 0x8c, 0x5b, 0x7f, 0xf6, 0xbf, 0xcc, 0x6f, 0x85, 0x03, 0x58,
+    0xc3, 0x68, 0x51, 0x13, 0xcd, 0xfd, 0xc8, 0xf7, 0x79, 0x3d, 0x99, 0x35,
+    0xf0, 0x56, 0xa3, 0xbd, 0xe0, 0x59, 0xed, 0x4f, 0x44, 0x09, 0xa3, 0x9e,
+    0x38, 0x7a, 0xf6, 0x46, 0xd1, 0x1d, 0x12, 0x9d, 0x4f, 0xbe, 0xd0, 0x40,
+    0xfc, 0x55, 0xfe, 0x06, 0x5e, 0x3c, 0xda, 0x1c, 0x56, 0xbd, 0x96, 0x51,
+    0x7b, 0x6f, 0x57, 0x2a, 0xdb, 0xa2, 0xaa, 0x96, 0xdc, 0x8c, 0x74, 0xc2,
+    0x95, 0xbe, 0xf0, 0x6e, 0x95, 0x13, 0xff, 0x17, 0xf0, 0x3c, 0xac, 0xb2,
+    0x10, 0x8d, 0xcc, 0x73, 0xfb, 0xe8, 0x8f, 0x02, 0xc6, 0xf0, 0xfb, 0x33,
+    0xb3, 0x95, 0x3b, 0xe3, 0xc2, 0xcb, 0x68, 0x58, 0x73, 0xdb, 0xa8, 0x24,
+    0x62, 0x3b, 0x06, 0x35, 0x9d, 0x0d, 0xa9, 0x33, 0xbd, 0x78, 0x03, 0x90,
+    0x2e, 0x4c, 0x78, 0x5d, 0x50, 0x3a, 0x81, 0xd4, 0xee, 0xa0, 0xc8, 0x70,
+    0x38, 0xdc, 0xb2, 0xf9, 0x67, 0xfa, 0x87, 0x40, 0x5d, 0x61, 0xc0, 0x51,
+    0x8f, 0x6b, 0x83, 0x6b, 0xcd, 0x05, 0x3a, 0xca, 0xe1, 0xa7, 0x05, 0x78,
+    0xfc, 0xca, 0xda, 0x94, 0xd0, 0x2c, 0x08, 0x3d, 0x7e, 0x16, 0x79, 0xc8,
+    0xa0, 0x50, 0x20, 0x24, 0x54, 0x33, 0x71, 0x31, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00,
+};
+
+static int test_reparse() {
+  CBS pkcs7;
+  CBB cbb;
+  STACK_OF(X509) *certs = sk_X509_new_null();
+  STACK_OF(X509) *certs2 = sk_X509_new_null();
+  uint8_t *result_data, *result2_data;
+  size_t result_len, result2_len, i;
+
+  CBS_init(&pkcs7, kPKCS7DER, sizeof(kPKCS7DER));
+  if (!PKCS7_get_certificates(certs, &pkcs7)) {
+    fprintf(stderr, "PKCS7_get_certificates failed.\n");
+    return 0;
+  }
+
+  CBB_init(&cbb, sizeof(kPKCS7DER));
+  if (!PKCS7_bundle_certificates(&cbb, certs) ||
+      !CBB_finish(&cbb, &result_data, &result_len)) {
+    fprintf(stderr, "PKCS7_bundle_certificates failed.\n");
+    return 0;
+  }
+
+  CBS_init(&pkcs7, result_data, result_len);
+  if (!PKCS7_get_certificates(certs2, &pkcs7)) {
+    fprintf(stderr, "PKCS7_get_certificates reparse failed.\n");
+    return 0;
+  }
+
+  if (sk_X509_num(certs) != sk_X509_num(certs2)) {
+    fprintf(stderr, "Number of certs in results differ.\n");
+    return 0;
+  }
+
+  for (i = 0; i < sk_X509_num(certs); i++) {
+    X509 *a = sk_X509_value(certs, i);
+    X509 *b = sk_X509_value(certs2, i);
+
+    if (X509_cmp(a, b) != 0) {
+      fprintf(stderr, "Certificate %u differs.\n", (unsigned) i);
+      return 0;
+    }
+  }
+
+  CBB_init(&cbb, sizeof(kPKCS7DER));
+  if (!PKCS7_bundle_certificates(&cbb, certs2) ||
+      !CBB_finish(&cbb, &result2_data, &result2_len)) {
+    fprintf(stderr,
+            "PKCS7_bundle_certificates failed the second time.\n");
+    return 0;
+  }
+
+  if (result_len != result2_len ||
+      memcmp(result_data, result2_data, result_len) != 0) {
+    fprintf(stderr, "Serialisation is not stable.\n");
+    return 0;
+  }
+
+  OPENSSL_free(result_data);
+  OPENSSL_free(result2_data);
+  sk_X509_pop_free(certs, X509_free);
+  sk_X509_pop_free(certs2, X509_free);
+
+  return 1;
+}
+
+int main() {
+  if (!test_reparse()) {
+    return 1;
+  }
+
+  printf("PASS\n");
+  return 0;
+}
+
diff --git a/include/openssl/bytestring.h b/include/openssl/bytestring.h
index 510ef7e..6c0e799 100644
--- a/include/openssl/bytestring.h
+++ b/include/openssl/bytestring.h
@@ -245,6 +245,12 @@
  * success and zero otherwise. */
 OPENSSL_EXPORT int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len);
 
+/* CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to
+ * the beginning of that space. The caller must then write |len| bytes of
+ * actual contents to |*out_data|. It returns one on success and zero
+ * otherwise. */
+OPENSSL_EXPORT int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len);
+
 /* CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on
  * success and zero otherwise. */
 OPENSSL_EXPORT int CBB_add_u8(CBB *cbb, uint8_t value);
diff --git a/include/openssl/obj.h b/include/openssl/obj.h
index f868fd3..81066bb 100644
--- a/include/openssl/obj.h
+++ b/include/openssl/obj.h
@@ -59,6 +59,7 @@
 
 #include <openssl/base.h>
 
+#include <openssl/bytestring.h>
 #include <openssl/obj_mac.h>
 
 #if defined(__cplusplus)
@@ -127,6 +128,10 @@
 /* OBJ_nid2sn returns the long name for |nid|, or NULL if |nid| is unknown. */
 OPENSSL_EXPORT const char *OBJ_nid2ln(int nid);
 
+/* OBJ_nid2cbs writes |nid| as an ASN.1 OBJECT IDENTIFIER to |out|. It returns
+ * one on success or zero otherwise. */
+OPENSSL_EXPORT int OBJ_nid2cbb(CBB *out, int nid);
+
 
 /* Dealing with textual representations of object identifiers. */
 
diff --git a/include/openssl/x509.h b/include/openssl/x509.h
index 058bbff..ac23f9c 100644
--- a/include/openssl/x509.h
+++ b/include/openssl/x509.h
@@ -1195,6 +1195,11 @@
  * and zero on error. */
 OPENSSL_EXPORT int PKCS7_get_certificates(STACK_OF(X509) *out_certs, CBS *cbs);
 
+/* PKCS7_bundle_certificates appends a PKCS#7, SignedData structure containing
+ * |certs| to |cbb|. It returns one on success and zero on error. */
+OPENSSL_EXPORT int PKCS7_bundle_certificates(
+    CBB *out, const STACK_OF(X509) *certs);
+
 
 /* EVP_PK values indicate the algorithm of the public key in a certificate. */
 
diff --git a/util/all_tests.sh b/util/all_tests.sh
index 7fe97ab..178c30b 100644
--- a/util/all_tests.sh
+++ b/util/all_tests.sh
@@ -45,6 +45,7 @@
 ./crypto/x509v3/tab_test
 ./crypto/x509v3/v3name_test
 ./crypto/bytestring/bytestring_test
+./crypto/x509/pkcs7_test
 ./ssl/ssl_test
 "