--- httpd-2.4.34/modules/proxy/ajp_header.c.r1738878
+++ httpd-2.4.34/modules/proxy/ajp_header.c
@@ -213,7 +213,8 @@
 
 static apr_status_t ajp_marshal_into_msgb(ajp_msg_t *msg,
                                           request_rec *r,
-                                          apr_uri_t *uri)
+                                          apr_uri_t *uri,
+                                          const char *secret)
 {
     int method;
     apr_uint32_t i, num_headers = 0;
@@ -293,17 +294,15 @@
                    i, elts[i].key, elts[i].val);
     }
 
-/* XXXX need to figure out how to do this
-    if (s->secret) {
+    if (secret) {
         if (ajp_msg_append_uint8(msg, SC_A_SECRET) ||
-            ajp_msg_append_string(msg, s->secret)) {
+            ajp_msg_append_string(msg, secret)) {
             ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(03228)
-                   "Error ajp_marshal_into_msgb - "
+                   "ajp_marshal_into_msgb: "
                    "Error appending secret");
             return APR_EGENERAL;
         }
     }
- */
 
     if (r->user) {
         if (ajp_msg_append_uint8(msg, SC_A_REMOTE_USER) ||
@@ -671,7 +670,8 @@
 apr_status_t ajp_send_header(apr_socket_t *sock,
                              request_rec *r,
                              apr_size_t buffsize,
-                             apr_uri_t *uri)
+                             apr_uri_t *uri,
+                             const char *secret)
 {
     ajp_msg_t *msg;
     apr_status_t rc;
@@ -683,7 +683,7 @@
         return rc;
     }
 
-    rc = ajp_marshal_into_msgb(msg, r, uri);
+    rc = ajp_marshal_into_msgb(msg, r, uri, secret);
     if (rc != APR_SUCCESS) {
         ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00988)
                "ajp_send_header: ajp_marshal_into_msgb failed");
--- httpd-2.4.34/modules/proxy/ajp.h.r1738878
+++ httpd-2.4.34/modules/proxy/ajp.h
@@ -413,12 +413,14 @@
  * @param sock      backend socket
  * @param r         current request
  * @param buffsize  max size of the AJP packet.
+ * @param secret    authentication secret
  * @param uri       requested uri
  * @return          APR_SUCCESS or error
  */
 apr_status_t ajp_send_header(apr_socket_t *sock, request_rec *r,
                              apr_size_t buffsize,
-                             apr_uri_t *uri);
+                             apr_uri_t *uri,
+                             const char *secret);
 
 /**
  * Read the ajp message and return the type of the message.
--- httpd-2.4.34/modules/proxy/mod_proxy_ajp.c.r1738878
+++ httpd-2.4.34/modules/proxy/mod_proxy_ajp.c
@@ -193,6 +193,7 @@
     apr_off_t content_length = 0;
     int original_status = r->status;
     const char *original_status_line = r->status_line;
+    const char *secret = NULL;
 
     if (psf->io_buffer_size_set)
        maxsize = psf->io_buffer_size;
@@ -202,12 +203,15 @@
        maxsize = AJP_MSG_BUFFER_SZ;
     maxsize = APR_ALIGN(maxsize, 1024);
 
+    if (*conn->worker->s->secret)
+        secret = conn->worker->s->secret;
+
     /*
      * Send the AJP request to the remote server
      */
 
     /* send request headers */
-    status = ajp_send_header(conn->sock, r, maxsize, uri);
+    status = ajp_send_header(conn->sock, r, maxsize, uri, secret);
     if (status != APR_SUCCESS) {
         conn->close = 1;
         ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r, APLOGNO(00868)
--- httpd-2.4.34/modules/proxy/mod_proxy.c.r1738878
+++ httpd-2.4.34/modules/proxy/mod_proxy.c
@@ -319,6 +319,12 @@
                                 (int)sizeof(worker->s->upgrade));
         }
     }
+    else if (!strcasecmp(key, "secret")) {
+        if (PROXY_STRNCPY(worker->s->secret, val) != APR_SUCCESS) {
+            return apr_psprintf(p, "Secret length must be < %d characters",
+                                (int)sizeof(worker->s->secret));
+        }
+    }
     else if (!strcasecmp(key, "responsefieldsize")) {
         long s = atol(val);
         if (s < 0) {
--- httpd-2.4.34/modules/proxy/mod_proxy.h.r1738878
+++ httpd-2.4.34/modules/proxy/mod_proxy.h
@@ -357,6 +357,7 @@
 #define PROXY_WORKER_MAX_HOSTNAME_SIZE  64
 #define PROXY_BALANCER_MAX_HOSTNAME_SIZE PROXY_WORKER_MAX_HOSTNAME_SIZE
 #define PROXY_BALANCER_MAX_STICKY_SIZE  64
+#define PROXY_WORKER_MAX_SECRET_SIZE    64
 
 #define PROXY_RFC1035_HOSTNAME_SIZE	256
 
@@ -453,6 +454,7 @@
     char      hostname_ex[PROXY_RFC1035_HOSTNAME_SIZE];  /* RFC1035 compliant version of the remote backend address */
     apr_size_t   response_field_size; /* Size of proxy response buffer in bytes. */
     unsigned int response_field_size_set:1;
+    char      secret[PROXY_WORKER_MAX_SECRET_SIZE]; /* authentication secret (e.g. AJP13) */
 } proxy_worker_shared;
 
 #define ALIGNED_PROXY_WORKER_SHARED_SIZE (APR_ALIGN_DEFAULT(sizeof(proxy_worker_shared)))