irmd: Initial Flow Allocation Protocol Header

This adds the initial version for the flow allocation protocol header
between IRMd instances. This is a step towards flow authentication.

The header supports secure and authenticated flow allocation,
supporting certificate-based authentication and ephemeral key
exchange for end-to-end encryption.

 id:          128-bit identifier for the entity.
 timestamp:   64-bit timestamp (replay protection).
 certificate: Certificate for authentication.
 public key:  ECDHE public key for key exchange.
 data:        Application data.
 signature:   Signature for integrity/authenticity.

Authentication and encryption require OpenSSL to be installed.

The IRMd compares the allocation request delay with the MPL of the
Layer over which the flow allocation was sent. MPL is now reported by
the Layer in ms instead of seconds.

Time functions revised for consistency and adds some tests.

The TPM can now print thread running times in Debug builds
(TPM_DEBUG_REPORT_INTERVAL) and abort processes with hung threads
(TPM_DEBUG_ABORT_TIMEOUT). Long running threads waiting for input
should call tpm_wait_work() to avoid trigger a process abort.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

12 files changed, 795 insertions, 127 deletions

diff --git a/src/irmd/CMakeLists.txt b/src/irmd/CMakeLists.txt
index c7e4cbd9..fce89bef 100644
--- a/src/irmd/CMakeLists.txt
+++ b/src/irmd/CMakeLists.txt
@@ -71,6 +71,7 @@ set(SOURCE_FILES
   ipcp.c
   configfile.c
   main.c
+  oap.c
   reg/flow.c
   reg/ipcp.c
   reg/proc.c
@@ -95,6 +96,5 @@ endif ()
 
 install(TARGETS irmd RUNTIME DESTINATION ${CMAKE_INSTALL_SBINDIR})
 
-# Enable once irmd has tests
-#add_subdirectory(tests)
 add_subdirectory(reg)
+add_subdirectory(tests)
diff --git a/src/irmd/config.h.in b/src/irmd/config.h.in
index fa1156b9..aa37b0ac 100644
--- a/src/irmd/config.h.in
+++ b/src/irmd/config.h.in
@@ -66,6 +66,7 @@
 
 #cmakedefine IRMD_KILL_ALL_PROCESSES
 #cmakedefine HAVE_LIBGCRYPT
+#cmakedefine HAVE_OPENSSL
 
 #define O7S_ASCII_ART                                                          \
 "\n"                                                                       \
diff --git a/src/irmd/ipcp.c b/src/irmd/ipcp.c
index 28f870a7..8a42be42 100644
--- a/src/irmd/ipcp.c
+++ b/src/irmd/ipcp.c
@@ -170,7 +170,7 @@ ipcp_msg_t * send_recv_ipcp_msg(pid_t        pid,
                 recv_msg = ipcp_msg__unpack(NULL, len, buf);
         else {
                 if (errno == EAGAIN && !dealloc) {
-                        int diff = ts_diff_ms(&tic, &toc);
+                        int diff = ts_diff_ms(&toc, &tic);
                         log_warn("IPCP %s timed out after %d ms.",
                                  str_ipcp_cmd(msg->code), diff);
                 }
diff --git a/src/irmd/main.c b/src/irmd/main.c
index cf079698..5cda9559 100644
--- a/src/irmd/main.c
+++ b/src/irmd/main.c
@@ -40,6 +40,7 @@
 #include <ouroboros/lockfile.h>
 #include <ouroboros/logs.h>
 #include <ouroboros/pthread.h>
+#include <ouroboros/random.h>
 #include <ouroboros/rib.h>
 #include <ouroboros/shm_rdrbuff.h>
 #include <ouroboros/sockets.h>
@@ -50,6 +51,7 @@
 
 #include "irmd.h"
 #include "ipcp.h"
+#include "oap.h"
 #include "reg/reg.h"
 #include "configfile.h"
 
@@ -760,66 +762,46 @@ static void __cleanup_flow(void * flow)
 }
 
 static int flow_accept(struct flow_info * flow,
+                       buffer_t *         symmkey,
                        buffer_t *         data,
                        struct timespec *  abstime)
 {
-        uint8_t   buf[MSGBUFSZ];
-        buffer_t  lpk; /* local public key           */
-        buffer_t  rpk; /* remote public key          */
-        void *    pkp; /* my public/private key pair */
-        ssize_t   key_len;
-        uint8_t * s;
-        int       err;
+        struct oap_hdr  oap_hdr;        /* incoming request           */
+        struct oap_hdr  r_oap_hdr;      /* outgoing response          */
+        uint8_t         buf[MSGBUFSZ];  /* buffer for local ephkey    */
+        buffer_t        lpk = BUF_INIT; /* local ephemeral pubkey     */
+        int             err;
+        struct timespec now;
 
         /* piggyback of user data not yet implemented */
         assert(data != NULL && data->len == 0 && data->data == NULL);
+        assert(symmkey != NULL && symmkey->len == 0 && symmkey->data == NULL);
 
         if (!reg_has_proc(flow->n_pid)) {
                 log_err("Unknown process %d calling accept.", flow->n_pid);
                 err = -EINVAL;
-                goto fail;
-        }
-
-        s = malloc(SYMMKEYSZ);
-        if (s == NULL) {
-                log_err("Failed to malloc symmkey.");
-                err = -ENOMEM;
-                goto fail;
-        }
-
-        key_len = crypt_dh_pkp_create(&pkp, buf);
-        if (key_len < 0) {
-                log_err("Failed to generate key pair.");
-                err = -ECRYPT;
-                goto fail_pkp;
+                goto fail_flow;
         }
 
-        lpk.data = buf;
-        lpk.len  = (size_t) key_len;
-
-        log_dbg("Generated ephemeral keys for %d.", flow->n_pid);
-
         if (reg_create_flow(flow) < 0) {
                 log_err("Failed to create flow.");
                 err = -EBADF;
                 goto fail_flow;
         }
 
-        if (reg_prepare_flow_accept(flow, &lpk) < 0) {
+        if (reg_prepare_flow_accept(flow) < 0) {
                 log_err("Failed to prepare accept.");
                 err = -EBADF;
                 goto fail_wait;
         }
 
+        log_dbg("Waiting for flow accept %d.", flow->id);
+
         pthread_cleanup_push(__cleanup_flow, flow);
-        pthread_cleanup_push(__cleanup_pkp, pkp);
-        pthread_cleanup_push(free, s);
 
-        err = reg_wait_flow_accepted(flow, &rpk, abstime);
+        err = reg_wait_flow_accepted(flow, &oap_hdr.hdr, abstime);
 
         pthread_cleanup_pop(false);
-        pthread_cleanup_pop(false);
-        pthread_cleanup_pop(false);
 
         if (err == -ETIMEDOUT) {
                 log_err("Flow accept timed out.");
@@ -834,45 +816,96 @@ static int flow_accept(struct flow_info * flow,
 
         assert(err == 0);
 
-        if (flow->qs.cypher_s != 0) { /* crypto requested */
-                if (crypt_dh_derive(pkp, rpk, s) < 0) {
+        if (oap_hdr_decode(oap_hdr.hdr, &oap_hdr) < 0) {
+                log_err("Failed to decode OAP header.");
+                err = -EIPCP;
+                goto fail_oap_hdr;
+        }
+
+        clock_gettime(CLOCK_REALTIME, &now);
+
+        if (now.tv_sec - (time_t) (oap_hdr.timestamp / MILLION) > flow->mpl)
+                log_warn("Flow alloc time exceeds MPL by %zu ms.",
+                        now.tv_sec - oap_hdr.timestamp / MILLION);
+
+        if (flow->qs.cypher_s != 0) {     /* crypto requested           */
+                uint8_t * s;              /* symmetric encryption key   */
+                ssize_t   key_len;        /* length of local pubkey     */
+                void *    pkp = NULL;     /* ephemeral private key pair */
+
+                s = malloc(SYMMKEYSZ);
+                if (s == NULL) {
+                        log_err("Failed to malloc symmkey.");
+                        err = -ENOMEM;
+                        goto fail_keys;
+                }
+
+                key_len = crypt_dh_pkp_create(&pkp, buf);
+                if (key_len < 0) {
+                        free(s);
+                        log_err("Failed to generate key pair.");
+                        err = -ECRYPT;
+                        goto fail_keys;
+                }
+
+                lpk.data = buf;
+                lpk.len  = (size_t) key_len;
+
+                log_dbg("Generated ephemeral keys for %d.", flow->n_pid);
+
+                if (crypt_dh_derive(pkp, oap_hdr.eph, s) < 0) {
                         log_err("Failed to derive secret for %d.", flow->id);
+                        crypt_dh_pkp_destroy(pkp);
+                        free(s);
                         err = -ECRYPT;
                         goto fail_derive;
                 }
-                freebuf(rpk);
-                data->data = s;
-                data->len  = SYMMKEYSZ;
-                s= NULL;
-        } else {
-                clrbuf(lpk);
+
+                symmkey->data = s;
+                symmkey->len  = SYMMKEYSZ;
+
+                crypt_dh_pkp_destroy(pkp);
+        }
+
+        if (oap_hdr_init(oap_hdr.id, NULL, NULL, lpk, *data, &r_oap_hdr) < 0) {
+                log_err("Failed to create OAP header.");
+                err = -ENOMEM;
+                goto fail_r_oap_hdr;
         }
 
-        if (ipcp_flow_alloc_resp(flow, 0, lpk) < 0) {
+        if (ipcp_flow_alloc_resp(flow, 0, r_oap_hdr.hdr) < 0) {
                 log_err("Failed to respond to flow allocation.");
-                err = -EIPCP;
-                goto fail_alloc_resp;
+                goto fail_resp;
         }
 
-        crypt_dh_pkp_destroy(pkp);
-        free(s);
+        oap_hdr_fini(&oap_hdr);
+        oap_hdr_fini(&r_oap_hdr);
 
         return 0;
 
+ fail_r_oap_hdr:
+        freebuf(*symmkey);
  fail_derive:
-        freebuf(rpk);
         clrbuf(lpk);
+ fail_keys:
+        oap_hdr_fini(&oap_hdr);
+ fail_oap_hdr:
+        assert(lpk.data == NULL && lpk.len == 0);
         ipcp_flow_alloc_resp(flow, err, lpk);
- fail_alloc_resp:
-        flow->state = FLOW_NULL;
  fail_wait:
         reg_destroy_flow(flow->id);
  fail_flow:
-        crypt_dh_pkp_destroy(pkp);
- fail_pkp:
-        free(s);
- fail:
         return err;
+
+ fail_resp:
+        flow->state = FLOW_NULL;
+        oap_hdr_fini(&r_oap_hdr);
+        freebuf(*symmkey);
+        clrbuf(lpk);
+        oap_hdr_fini(&oap_hdr);
+        assert(lpk.data == NULL && lpk.len == 0);
+        reg_destroy_flow(flow->id);
+        return -EIPCP;
 }
 
 static int flow_join(struct flow_info * flow,
@@ -910,6 +943,7 @@ static int flow_join(struct flow_info * flow,
 
         reg_prepare_flow_alloc(flow);
 
+
         if (ipcp_flow_join(flow, hash)) {
                 log_err("Flow join with layer %s failed.", dst);
                 err = -ENOTALLOC;
@@ -935,6 +969,7 @@ static int flow_join(struct flow_info * flow,
                 goto fail_alloc;
         }
 
+        assert(pbuf.data == NULL && pbuf.len == 0);
         assert(err == 0);
 
         freebuf(hash);
@@ -1008,20 +1043,33 @@ static int get_ipcp_by_dst(const char *     dst,
 
 static int flow_alloc(struct flow_info * flow,
                       const char *       dst,
+                      buffer_t *         symmkey,
                       buffer_t *         data,
                       struct timespec *  abstime)
 {
-        uint8_t   buf[MSGBUFSZ];
-        buffer_t  lpk ={NULL, 0}; /* local public key           */
-        buffer_t  rpk;            /* remote public key          */
-        void *    pkp = NULL;     /* my public/private key pair */
-        uint8_t * s = NULL;
-        buffer_t  hash;
-        int       err;
+        struct oap_hdr oap_hdr;        /* outgoing request           */
+        struct oap_hdr r_oap_hdr;      /* incoming response          */
+        uint8_t        buf[MSGBUFSZ];  /* buffer for local ephkey    */
+        buffer_t       lpk = BUF_INIT; /* local ephemeral pubkey     */
+        void *         pkp = NULL;     /* ephemeral private key pair */
+        uint8_t *      s = NULL;       /* symmetric key              */
+        buffer_t       hash;
+        uint8_t        idbuf[OAP_ID_SIZE];
+        buffer_t       id;
+        int            err;
+
         /* piggyback of user data not yet implemented */
         assert(data != NULL && data->len == 0 && data->data == NULL);
+        assert(symmkey != NULL && symmkey->len == 0 && symmkey->data == NULL);
 
-        log_info("Allocating flow for %d to %s.", flow->n_pid, dst);
+        if (random_buffer(idbuf, OAP_ID_SIZE) < 0) {
+                log_err("Failed to generate ID.");
+                err = -EIRMD;
+                goto fail_id;
+        }
+
+        id.data = idbuf;
+        id.len  = OAP_ID_SIZE;
 
         if (flow->qs.cypher_s > 0) {
                 ssize_t key_len;
@@ -1046,6 +1094,14 @@ static int flow_alloc(struct flow_info * flow,
                 log_dbg("Generated ephemeral keys for %d.", flow->n_pid);
         }
 
+        if (oap_hdr_init(id, NULL, NULL, lpk, *data, &oap_hdr) < 0) {
+                log_err("Failed to create OAP header.");
+                err = -ENOMEM;
+                goto fail_oap_hdr;
+        }
+
+        log_info("Allocating flow for %d to %s.", flow->n_pid, dst);
+
         if (reg_create_flow(flow) < 0) {
                 log_err("Failed to create flow.");
                 err = -EBADF;
@@ -1060,7 +1116,7 @@ static int flow_alloc(struct flow_info * flow,
 
         reg_prepare_flow_alloc(flow);
 
-        if (ipcp_flow_alloc(flow, hash, lpk)) {
+        if (ipcp_flow_alloc(flow, hash, oap_hdr.hdr)) {
                 log_err("Flow allocation %d failed.", flow->id);
                 err = -ENOTALLOC;
                 goto fail_alloc;
@@ -1071,7 +1127,7 @@ static int flow_alloc(struct flow_info * flow,
         pthread_cleanup_push(free, hash.data);
         pthread_cleanup_push(free, s);
 
-        err = reg_wait_flow_allocated(flow, &rpk, abstime);
+        err = reg_wait_flow_allocated(flow, &r_oap_hdr.hdr, abstime);
 
         pthread_cleanup_pop(false);
         pthread_cleanup_pop(false);
@@ -1091,37 +1147,57 @@ static int flow_alloc(struct flow_info * flow,
 
         assert(err == 0);
 
+        if (oap_hdr_decode(r_oap_hdr.hdr, &r_oap_hdr) < 0) {
+                log_err("Failed to decode OAP header.");
+                err = -EIPCP;
+                goto fail_r_oap_hdr;
+        }
+
+        if (memcmp(r_oap_hdr.id.data, oap_hdr.id.data, r_oap_hdr.id.len) != 0) {
+                log_err("OAP ID mismatch in flow allocation.");
+                err = -EIPCP;
+                goto fail_r_oap_hdr;
+        }
+
         if (flow->qs.cypher_s != 0) { /* crypto requested */
-                if (crypt_dh_derive(pkp, rpk, s) < 0) {
+                if (crypt_dh_derive(pkp, r_oap_hdr.eph, s) < 0) {
                         log_err("Failed to derive secret for %d.", flow->id);
                         err = -ECRYPT;
-                        goto fail_derive;
+                        goto fail_r_oap_hdr;
                 }
                 crypt_dh_pkp_destroy(pkp);
-                freebuf(rpk);
-                data->data = s;
-                data->len  = SYMMKEYSZ;
+
+                symmkey->data = s;
+                symmkey->len  = SYMMKEYSZ;
                 s = NULL;
         }
 
+        oap_hdr_fini(&r_oap_hdr);
+        oap_hdr_fini(&oap_hdr);
+
+        /* TODO: piggyback user data if needed */
+
         freebuf(hash);
         free(s);
 
         return 0;
 
- fail_derive:
-        freebuf(rpk);
+ fail_r_oap_hdr:
         flow->state = FLOW_DEALLOCATED;
+        oap_hdr_fini(&r_oap_hdr);
  fail_alloc:
         freebuf(hash);
  fail_ipcp:
         reg_destroy_flow(flow->id);
  fail_flow:
-        if (flow->qs.cypher_s > 0)
-               crypt_dh_pkp_destroy(pkp);
+        oap_hdr_fini(&oap_hdr);
+ fail_oap_hdr:
+        crypt_dh_pkp_destroy(pkp);
  fail_pkp:
         free(s);
  fail_malloc:
+        clrbuf(id);
+ fail_id:
         return err;
 }
 
@@ -1325,6 +1401,7 @@ static irm_msg_t * do_command_msg(irm_msg_t * msg)
         int                res;
         irm_msg_t *        ret_msg;
         buffer_t           data;
+        buffer_t           symmkey = BUF_INIT;;
 
         memset(&flow, 0, sizeof(flow));
 
@@ -1421,17 +1498,21 @@ static irm_msg_t * do_command_msg(irm_msg_t * msg)
                 res = name_unreg(msg->name, msg->pid);
                 break;
         case IRM_MSG_CODE__IRM_FLOW_ACCEPT:
+                tpm_wait_work(irmd.tpm);
                 data.len  = msg->pk.len;
                 data.data = msg->pk.data;
                 msg->has_pk = false;
                 assert(data.len > 0 ? data.data != NULL : data.data == NULL);
                 flow = flow_info_msg_to_s(msg->flow_info);
-                res = flow_accept(&flow, &data, abstime);
+                res = flow_accept(&flow, &symmkey, &data, abstime);
                 if (res == 0) {
                         ret_msg->flow_info    = flow_info_s_to_msg(&flow);
-                        ret_msg->has_symmkey  = data.len != 0;
-                        ret_msg->symmkey.data = data.data;
-                        ret_msg->symmkey.len  = data.len;
+                        ret_msg->has_symmkey  = symmkey.len != 0;
+                        ret_msg->symmkey.data = symmkey.data;
+                        ret_msg->symmkey.len  = symmkey.len;
+                        ret_msg->has_pk       = data.len != 0;
+                        ret_msg->pk.data      = data.data;
+                        ret_msg->pk.len       = data.len;
                 }
                 break;
         case IRM_MSG_CODE__IRM_FLOW_ALLOC:
@@ -1441,12 +1522,15 @@ static irm_msg_t * do_command_msg(irm_msg_t * msg)
                 assert(data.len > 0 ? data.data != NULL : data.data == NULL);
                 flow = flow_info_msg_to_s(msg->flow_info);
                 abstime = abstime == NULL ? &max : abstime;
-                res = flow_alloc(&flow, msg->dst, &data, abstime);
+                res = flow_alloc(&flow, msg->dst, &symmkey, &data, abstime);
                 if (res == 0) {
                         ret_msg->flow_info    = flow_info_s_to_msg(&flow);
-                        ret_msg->has_symmkey  = data.len != 0;
-                        ret_msg->symmkey.data = data.data;
-                        ret_msg->symmkey.len  = data.len;
+                        ret_msg->has_symmkey  = symmkey.len != 0;
+                        ret_msg->symmkey.data = symmkey.data;
+                        ret_msg->symmkey.len  = symmkey.len;
+                        ret_msg->has_pk       = data.len != 0;
+                        ret_msg->pk.data      = data.data;
+                        ret_msg->pk.len       = data.len;
                 }
                 break;
         case IRM_MSG_CODE__IRM_FLOW_JOIN:
diff --git a/src/irmd/oap.c b/src/irmd/oap.c
new file mode 100644
index 00000000..d5e5b7cc
--- /dev/null
+++ b/src/irmd/oap.c
@@ -0,0 +1,220 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2024
+ *
+ * Ouroboros flow allocation protocol header
+ *
+ *    Dimitri Staessens <dimitri@ouroboros.rocks>
+ *    Sander Vrijders   <sander@ouroboros.rocks>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+#if defined(__linux__) || defined(__CYGWIN__)
+ #define _DEFAULT_SOURCE
+#else
+ #define _POSIX_C_SOURCE 200809L
+#endif
+
+#include <ouroboros/crypt.h>
+#include <ouroboros/endian.h>
+#include <ouroboros/time.h>
+
+#include "oap.h"
+
+#include <assert.h>
+
+int oap_hdr_init(buffer_t         id,
+                 void *           pkp,
+                 void *           pubcrt,
+                 buffer_t         ephkey,
+                 buffer_t         data,
+                 struct oap_hdr * oap_hdr)
+{
+        struct timespec now;
+        uint64_t        stamp;
+        buffer_t        hdr;
+        buffer_t        der = BUF_INIT;
+        buffer_t        sig = BUF_INIT;
+        buffer_t        sign;
+        uint16_t        len;
+        off_t           offset;
+
+        assert(id.data != NULL && id.len == OAP_ID_SIZE);
+        assert(oap_hdr != NULL);
+        memset(oap_hdr, 0, sizeof(*oap_hdr));
+
+        clock_gettime(CLOCK_REALTIME, &now);
+        stamp = hton64(TS_TO_UINT64(now));
+
+        if (pubcrt != NULL && crypt_crt_der(pubcrt, &der) < 0)
+                goto fail_der;
+
+        hdr.len = id.len +
+                sizeof(stamp) +
+                sizeof(len) + der.len +
+                sizeof(len) + ephkey.len +
+                sizeof(len) + data.len +
+                sizeof(len); /* sig len */
+
+        hdr.data = malloc(hdr.len);
+        if (hdr.data == NULL)
+                goto fail_hdr;
+
+        offset = 0;
+
+        memcpy(hdr.data, id.data, id.len);
+        offset += id.len;
+
+        memcpy(hdr.data + offset, &stamp, sizeof(stamp));
+        offset += sizeof(stamp);
+
+        /* pubcrt */
+        len = hton16((uint16_t) der.len);
+        memcpy(hdr.data + offset, &len, sizeof(len));
+        offset += sizeof(len);
+        if (der.len != 0)
+                memcpy(hdr.data + offset, der.data, der.len);
+        offset += der.len;
+
+        /* ephkey */
+        len = hton16((uint16_t) ephkey.len);
+        memcpy(hdr.data + offset, &len, sizeof(len));
+        offset += sizeof(len);
+        if (ephkey.len != 0)
+                memcpy(hdr.data + offset, ephkey.data, ephkey.len);
+        offset += ephkey.len;
+
+        /* data */
+        len = hton16((uint16_t) data.len);
+        memcpy(hdr.data + offset, &len, sizeof(len));
+        offset += sizeof(len);
+        if (data.len != 0)
+                memcpy(hdr.data + offset, data.data, data.len);
+        offset += data.len;
+
+        sign.data = hdr.data;
+        sign.len  = hdr.len - sizeof(len);
+
+        if (pkp != NULL && auth_sign(pkp, sign, &sig) < 0)
+                goto fail_sig;
+
+        len = hton16((uint16_t) sig.len);
+        memcpy(hdr.data + offset, &len, sizeof(len));
+        offset += sizeof(len);
+
+        oap_hdr->hdr = hdr;
+
+        assert((size_t) offset == hdr.len);
+
+        if (sig.len > 0) {
+                oap_hdr->hdr.len += sig.len;
+                oap_hdr->hdr.data = realloc(hdr.data, oap_hdr->hdr.len);
+                if (oap_hdr->hdr.data == NULL)
+                        goto fail_oap_hdr;
+
+                memcpy(oap_hdr->hdr.data + offset, sig.data, sig.len);
+                clrbuf(hdr);
+        }
+
+        if (oap_hdr_decode(oap_hdr->hdr, oap_hdr) < 0)
+                goto fail_decode;
+
+        freebuf(der);
+        freebuf(sig);
+
+        return 0;
+
+ fail_decode:
+        oap_hdr_fini(oap_hdr);
+ fail_oap_hdr:
+        freebuf(sig);
+ fail_sig:
+        freebuf(hdr);
+ fail_hdr:
+        freebuf(der);
+ fail_der:
+        memset(oap_hdr, 0, sizeof(*oap_hdr));
+        return -1;
+}
+
+void oap_hdr_fini(struct oap_hdr * oap_hdr)
+{
+        assert(oap_hdr != NULL);
+
+        freebuf(oap_hdr->hdr);
+        memset(oap_hdr, 0, sizeof(*oap_hdr));
+}
+
+int oap_hdr_decode(buffer_t             hdr,
+                   struct oap_hdr * oap_hdr)
+{
+        off_t offset;
+
+        assert(oap_hdr != NULL);
+        memset(oap_hdr, 0, sizeof(*oap_hdr));
+
+        if (hdr.len < OAP_HDR_MIN_SIZE)
+                goto fail_decode;
+
+        oap_hdr->id.data = hdr.data;
+        oap_hdr->id.len  = OAP_ID_SIZE;
+
+        offset = OAP_ID_SIZE;
+
+        oap_hdr->timestamp = ntoh64(*(uint64_t *)(hdr.data + offset));
+
+        offset += sizeof(uint64_t);
+
+        oap_hdr->crt.len = (size_t) ntoh16(*(uint16_t *)(hdr.data + offset));
+        oap_hdr->crt.data = hdr.data + offset + sizeof(uint16_t);
+
+        offset += sizeof(uint16_t) + oap_hdr->crt.len;
+
+        if ((size_t) offset + sizeof(uint16_t) >= hdr.len)
+                goto fail_decode;
+
+        oap_hdr->eph.len = (size_t) ntoh16(*(uint16_t *)(hdr.data + offset));
+        oap_hdr->eph.data = hdr.data + offset + sizeof(uint16_t);
+
+        offset += sizeof(uint16_t) + oap_hdr->eph.len;
+
+        if ((size_t) offset + sizeof(uint16_t) >= hdr.len)
+                goto fail_decode;
+
+        oap_hdr->data.len = (size_t) ntoh16(*(uint16_t *)(hdr.data + offset));
+        oap_hdr->data.data = hdr.data + offset + sizeof(uint16_t);
+
+        offset += sizeof(uint16_t) + oap_hdr->data.len;
+
+        if ((size_t) offset + sizeof(uint16_t) > hdr.len)
+                goto fail_decode;
+
+        oap_hdr->sig.len = (size_t) ntoh16(*(uint16_t *)(hdr.data + offset));
+        oap_hdr->sig.data = hdr.data + offset + sizeof(uint16_t);
+
+        offset += sizeof(uint16_t) + oap_hdr->sig.len;
+
+        if ((size_t) offset != hdr.len)
+                goto fail_decode;
+
+        oap_hdr->hdr = hdr;
+
+        return 0;
+
+ fail_decode:
+        memset(oap_hdr, 0, sizeof(*oap_hdr));
+        return -1;
+}
+
+
diff --git a/src/irmd/oap.h b/src/irmd/oap.h
new file mode 100644
index 00000000..460a89de
--- /dev/null
+++ b/src/irmd/oap.h
@@ -0,0 +1,88 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2024
+ *
+ * Ouroboros flow allocation protocol header
+ *
+ *    Dimitri Staessens <dimitri@ouroboros.rocks>
+ *    Sander Vrijders   <sander@ouroboros.rocks>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+#ifndef OUROBOROS_IRMD_OAP_H
+#define OUROBOROS_IRMD_OAP_H
+
+#include <ouroboros/utils.h>
+
+#define OAP_ID_SIZE      (16)
+#define OAP_HDR_MIN_SIZE (OAP_ID_SIZE + sizeof(uint64_t) + 4 * sizeof(uint16_t))
+
+
+/*
+ *  0                   1                   2                   3
+ *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +---------------------------------------------------------------+
+ * |                                                               |
+ * |                        id (128 bits)                          |
+ * |                                                               |
+ * |                                                               |
+ * +---------------------------------------------------------------+
+ * |                      timestamp (64 bits)                      |
+ * |                                                               |
+ * +---------------------------------------------------------------+
+ * |      crt_len  (16 bits)     |                                 |
+ * +-----------+-----------------+                                 |
+ * |                        certificate                            |
+ * |                                                               |
+ * +---------------------------------------------------------------+
+ * |      eph_len  (16 bits)     |                                 |
+ * +-----------+-----------------+                                 |
+ * |                   public key for ECDHE                        |
+ * |                                                               |
+ * +---------------------------------------------------------------+
+ * |     data_len (16 bits)      |                                 |
+ * +-----------+-----------------+                                 |
+ * |               piggy backed application data                   |
+ * |                                                               |
+ * +---------------------------------------------------------------+
+ * |     sig_len  (16 bits)      |                                 |
+ * +-----------+-----------------+                                 |
+ * |                         signature                             |
+ * |                                                               |
+ * +---------------------------------------------------------------+
+ */
+
+struct oap_hdr {
+        uint64_t timestamp;
+        buffer_t id;
+        buffer_t crt;
+        buffer_t eph;
+        buffer_t data;
+        buffer_t sig;
+        buffer_t hdr;
+};
+
+int  oap_hdr_init(buffer_t         id,
+                  void *           pkp,
+                  void *           pubcrt,
+                  buffer_t         ephkey,
+                  buffer_t         data,
+                  struct oap_hdr * oap_hdr);
+
+void oap_hdr_fini(struct oap_hdr * oap_hdr);
+
+int  oap_hdr_decode(buffer_t         hdr,
+                    struct oap_hdr * oap_hdr);
+
+#endif /* OUROBOROS_IRMD_OAP_H */
diff --git a/src/irmd/reg/reg.c b/src/irmd/reg/reg.c
index d95a4722..339e7fa0 100644
--- a/src/irmd/reg/reg.c
+++ b/src/irmd/reg/reg.c
@@ -1771,8 +1771,7 @@ int reg_respond_alloc(struct flow_info * info,
         return -1;
 }
 
-int reg_prepare_flow_accept(struct flow_info * info,
-                            buffer_t *         pbuf)
+int reg_prepare_flow_accept(struct flow_info * info)
 {
         struct reg_flow * flow;
         int               ret;
@@ -1790,8 +1789,6 @@ int reg_prepare_flow_accept(struct flow_info * info,
 
         ret = reg_flow_update(flow, info);
 
-        reg_flow_set_data(flow, pbuf);
-
         pthread_mutex_unlock(&reg.mtx);
 
         return ret;
@@ -1915,7 +1912,6 @@ int reg_respond_accept(struct flow_info * info,
                        buffer_t *         pbuf)
 {
         struct reg_flow * flow;
-        buffer_t          temp;
 
         assert(info != NULL);
         assert(info->state == FLOW_ALLOCATED);
@@ -1933,11 +1929,8 @@ int reg_respond_accept(struct flow_info * info,
 
         info->n_pid = flow->info.n_pid;
 
-        if (info->qs.cypher_s > 0) {
-                reg_flow_get_data(flow, &temp);
-                reg_flow_set_data(flow, pbuf);
-                *pbuf = temp;
-        }
+        reg_flow_set_data(flow, pbuf);
+        clrbuf(pbuf);
 
         if (reg_flow_update(flow, info) < 0) {
                 log_err("Failed to create flow structs.");
diff --git a/src/irmd/reg/reg.h b/src/irmd/reg/reg.h
index 17dfcc32..f1899d65 100644
--- a/src/irmd/reg/reg.h
+++ b/src/irmd/reg/reg.h
@@ -119,8 +119,7 @@ int   reg_wait_flow_allocated(struct flow_info *      info,
 int   reg_respond_alloc(struct flow_info * info,
                         buffer_t *         pbuf);
 
-int   reg_prepare_flow_accept(struct flow_info * info,
-                              buffer_t *         pbuf);
+int   reg_prepare_flow_accept(struct flow_info * info);
 
 int   reg_wait_flow_accepted(struct flow_info *      info,
                              buffer_t *              pbuf,
diff --git a/src/irmd/reg/tests/reg_test.c b/src/irmd/reg/tests/reg_test.c
index 80fc64d6..b69cf476 100644
--- a/src/irmd/reg/tests/reg_test.c
+++ b/src/irmd/reg/tests/reg_test.c
@@ -115,7 +115,6 @@ static int test_reg_allocate_flow_timeout(void)
 {
         struct timespec abstime;
         struct timespec timeo = TIMESPEC_INIT_MS(1);
-        buffer_t        pbuf;
         buffer_t        rbuf = {NULL, 0};
 
         struct flow_info info = {
@@ -125,14 +124,6 @@ static int test_reg_allocate_flow_timeout(void)
 
         TEST_START();
 
-        pbuf.data = (uint8_t *) strdup(TEST_DATA);;
-        if (pbuf.data == NULL) {
-                printf("Failed to strdup data.\n");
-                goto fail;
-        }
-
-        pbuf.len  = strlen((char *) pbuf.data) + 1;
-
         clock_gettime(PTHREAD_COND_CLOCK, &abstime);
 
         ts_add(&abstime, &timeo, &abstime);
@@ -147,7 +138,7 @@ static int test_reg_allocate_flow_timeout(void)
                 goto fail;
         }
 
-        if (reg_prepare_flow_accept(&info, &pbuf) < 0) {
+        if (reg_prepare_flow_accept(&info) < 0) {
                 printf("Failed to prepare flow for accept.\n");
                 goto fail;
         }
@@ -162,12 +153,6 @@ static int test_reg_allocate_flow_timeout(void)
                 goto fail;
         }
 
-        if (pbuf.data == NULL) {
-                printf("Flow data was updated on timeout.");
-                goto fail;
-        }
-
-        freebuf(pbuf);
         reg_destroy_flow(info.id);
 
         if (reg.n_flows != 0) {
@@ -220,13 +205,6 @@ static void * test_flow_respond_accept(void * o)
 
         reg_respond_accept(info, &pbuf);
 
-        if (info->qs.cypher_s == 0) {
-                freebuf(pbuf);
-        } else if (strcmp((char *) pbuf.data, TEST_DATA) != 0) {
-                printf("Data was not passed correctly.\n");
-                goto fail;
-        }
-
         return (void *) 0;
  fail:
         return (void *) -1;
@@ -237,7 +215,6 @@ static int test_reg_accept_flow_success(void)
         pthread_t       thr;
         struct timespec abstime;
         struct timespec timeo = TIMESPEC_INIT_S(1);
-        buffer_t        pbuf = {(uint8_t *) TEST_DATA, strlen(TEST_DATA)};
         buffer_t        rbuf  = {NULL, 0};
 
         struct flow_info info = {
@@ -267,7 +244,7 @@ static int test_reg_accept_flow_success(void)
                 goto fail;
         }
 
-        if (reg_prepare_flow_accept(&info, &pbuf) < 0) {
+        if (reg_prepare_flow_accept(&info) < 0) {
                 printf("Failed to prepare flow for accept.\n");
                 goto fail;
         }
@@ -332,7 +309,6 @@ static int test_reg_accept_flow_success_no_crypt(void)
         pthread_t       thr;
         struct timespec abstime;
         struct timespec timeo = TIMESPEC_INIT_S(1);
-        buffer_t        pbuf = {(uint8_t *) TEST_DATA, strlen(TEST_DATA)};
         buffer_t        rbuf  = {NULL, 0};
 
         struct flow_info info = {
@@ -362,7 +338,7 @@ static int test_reg_accept_flow_success_no_crypt(void)
                 goto fail;
         }
 
-        if (reg_prepare_flow_accept(&info, &pbuf) < 0) {
+        if (reg_prepare_flow_accept(&info) < 0) {
                 printf("Failed to prepare flow for accept.\n");
                 goto fail;
         }
@@ -389,10 +365,7 @@ static int test_reg_accept_flow_success_no_crypt(void)
                 goto fail;
         }
 
-        if (strcmp((char *) rbuf.data, TEST_DATA) != 0) {
-                printf("Data was updated.\n");
-                goto fail;
-        }
+        freebuf(rbuf);
 
         n_1_info.state = FLOW_DEALLOCATED;
 
@@ -1177,7 +1150,7 @@ static void * test_call_flow_accept(void * o)
         clock_gettime(PTHREAD_COND_CLOCK, &abstime);
         ts_add(&abstime, &timeo, &abstime);
 
-        reg_prepare_flow_accept(&info, &pbuf);
+        reg_prepare_flow_accept(&info);
 
         if (reg_wait_flow_accepted(&info, &pbuf, &abstime) != -ETIMEDOUT) {
                 printf("Wait allocated did not timeout.\n");
diff --git a/src/irmd/tests/CMakeLists.txt b/src/irmd/tests/CMakeLists.txt
index 99743052..e860acce 100644
--- a/src/irmd/tests/CMakeLists.txt
+++ b/src/irmd/tests/CMakeLists.txt
@@ -3,6 +3,8 @@ get_filename_component(src_folder "${tmp}" NAME)
 
 create_test_sourcelist(${src_folder}_tests test_suite.c
   # Add new tests here
+  irm_test.c
+  oap_test.c
 )
 
 add_executable(${src_folder}_test EXCLUDE_FROM_ALL ${${src_folder}_tests})
@@ -21,3 +23,5 @@ foreach(test ${tests_to_run})
   get_filename_component(test_name ${test} NAME_WE)
   add_test(irmd/${test_name} ${C_TEST_PATH}/${src_folder}_test ${test_name})
 endforeach(test)
+
+set_property(TEST irmd/oap_test PROPERTY SKIP_RETURN_CODE 1)
diff --git a/src/irmd/tests/irm_test.c b/src/irmd/tests/irm_test.c
new file mode 100644
index 00000000..d440289c
--- /dev/null
+++ b/src/irmd/tests/irm_test.c
@@ -0,0 +1,33 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2024
+ *
+ * Unit tests of IRMd functions
+ *    Dimitri Staessens <dimitri@ouroboros.rocks>
+ *    Sander Vrijders   <sander@ouroboros.rocks>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+
+
+int irm_test(int argc,
+             char **argv)
+{
+        int ret = 0;
+
+        (void) argc;
+        (void) argv;
+
+        return ret;
+}
diff --git a/src/irmd/tests/oap_test.c b/src/irmd/tests/oap_test.c
new file mode 100644
index 00000000..e9f67505
--- /dev/null
+++ b/src/irmd/tests/oap_test.c
@@ -0,0 +1,273 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2024
+ *
+ * Unit tests of Ouroboros flow allocation protocol
+ *    Dimitri Staessens <dimitri@ouroboros.rocks>
+ *    Sander Vrijders   <sander@ouroboros.rocks>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+#include "config.h"
+
+#include "oap.c"
+
+#include <ouroboros/random.h>
+#include <ouroboros/test.h>
+
+static const char * pkp_str = \
+"-----BEGIN EC PRIVATE KEY-----\n"
+"MHcCAQEEIC13y+5jdKe80HBJD7WITpQamcn3rrkTX1r0v+JwSk4NoAoGCCqGSM49\n"
+"AwEHoUQDQgAEcC0yLAfUtufH8cdLybrdWPc6U+xRuhDhqqrEcBO5+eob2xyqEaNk\n"
+"nIV/86724zPptGRahWz0rzW2PvNppJdNBg==\n"
+"-----END EC PRIVATE KEY-----\n";
+
+/* Valid signed server certificate for server-2.unittest.o7s */
+static const char * crt_str = \
+"-----BEGIN CERTIFICATE-----\n"
+"MIIDgjCCAyigAwIBAgICEAIwCgYIKoZIzj0EAwIwWzELMAkGA1UEBhMCQkUxDDAK\n"
+"BgNVBAgMA09WTDEMMAoGA1UECgwDbzdzMRUwEwYDVQQLDAx1bml0dGVzdC5vN3Mx\n"
+"GTAXBgNVBAMMEGltMi51bml0dGVzdC5vN3MwHhcNMjUwNzA0MTMxODI5WhcNMzUw\n"
+"NzAyMTMxODI5WjBwMQswCQYDVQQGEwJCRTEMMAoGA1UECAwDT1ZMMQ4wDAYDVQQH\n"
+"DAVHaGVudDEMMAoGA1UECgwDbzdzMRUwEwYDVQQLDAx1bml0dGVzdC5vN3MxHjAc\n"
+"BgNVBAMMFXNlcnZlci0yLnVuaXR0ZXN0Lm83czBZMBMGByqGSM49AgEGCCqGSM49\n"
+"AwEHA0IABHAtMiwH1Lbnx/HHS8m63Vj3OlPsUboQ4aqqxHATufnqG9scqhGjZJyF\n"
+"f/Ou9uMz6bRkWoVs9K81tj7zaaSXTQajggHFMIIBwTAJBgNVHRMEAjAAMBEGCWCG\n"
+"SAGG+EIBAQQEAwIGQDA6BglghkgBhvhCAQ0ELRYrR3JpbGxlZCBDaGVlc2UgR2Vu\n"
+"ZXJhdGVkIFNlcnZlciBDZXJ0aWZpY2F0ZTAdBgNVHQ4EFgQUTt3xHTwE9amoglxh\n"
+"cEMqWv+PpDMwgb8GA1UdIwSBtzCBtIAUFfeZRx8QWWKQr7Aw8zjDu2shvcShgZek\n"
+"gZQwgZExCzAJBgNVBAYTAkJFMQwwCgYDVQQIDANPVkwxDjAMBgNVBAcMBUdoZW50\n"
+"MQwwCgYDVQQKDANvN3MxFTATBgNVBAsMDHVuaXR0ZXN0Lm83czEZMBcGA1UEAwwQ\n"
+"Y2EyLnVuaXR0ZXN0Lm83czEkMCIGCSqGSIb3DQEJARYVZHVtbXlAb3Vyb2Jvcm9z\n"
+"LnJvY2tzggIQAjAOBgNVHQ8BAf8EBAMCBaAwEwYDVR0lBAwwCgYIKwYBBQUHAwEw\n"
+"EQYDVR0fBAowCDAGoASgAoYAMCoGCCsGAQUFBwEBBB4wHDAMBggrBgEFBQcwAoYA\n"
+"MAwGCCsGAQUFBzABhgAwIAYDVR0RBBkwF4IVc2VydmVyLTEudW5pdHRlc3Qubzdz\n"
+"MAoGCCqGSM49BAMCA0gAMEUCIQDHuDb62w/Uah4nKwUFoJVkr4rgdNGh2Rn3SWaK\n"
+"0FV/gAIgOLKorTwSgrTFdyOUkuPOhRs8BEMpah+dp8UTO8AnLvY=\n"
+"-----END CERTIFICATE-----\n";
+
+static int test_oap_hdr_init_fini(void)
+{
+        struct oap_hdr  oap_hdr;
+        struct timespec now;
+        uint64_t        stamp;
+        buffer_t        ephkey = BUF_INIT;
+        buffer_t        data   = BUF_INIT;
+        uint8_t         buf[OAP_ID_SIZE];
+        buffer_t        id;
+        void *          pkp    = NULL;
+        void *          pubcrt = NULL;
+
+        TEST_START();
+
+        random_buffer(buf, OAP_ID_SIZE);
+        id.data = buf;
+        id.len  = OAP_ID_SIZE;
+
+        clock_gettime(CLOCK_REALTIME, &now);
+        stamp = TS_TO_UINT64(now);
+
+        if (oap_hdr_init(id, pkp, pubcrt, ephkey, data, &oap_hdr) < 0) {
+                printf("Failed to init OAP request header.\n");
+                goto fail_req_hdr;
+        }
+
+        if (oap_hdr.hdr.len != OAP_HDR_MIN_SIZE) {
+                printf("OAP request header wrong: %zu < %zu.\n",
+                       oap_hdr.hdr.len, OAP_HDR_MIN_SIZE);
+                goto fail_req_hdr_chk;
+        }
+
+        if (oap_hdr.id.len != OAP_ID_SIZE) {
+                printf("OAP request header ID wrong size: %zu != %zu.\n",
+                       oap_hdr.id.len, (size_t) OAP_ID_SIZE);
+                goto fail_req_hdr_chk;
+        }
+
+        if (memcmp(oap_hdr.id.data, id.data, OAP_ID_SIZE) != 0) {
+                printf("OAP request header ID mismatch.\n");
+                goto fail_req_hdr_chk;
+        }
+
+        if (oap_hdr.timestamp < stamp) {
+                printf("OAP request header timestamp is too old.\n");
+                goto fail_req_hdr_chk;
+        }
+
+        if (oap_hdr.timestamp > stamp + 1 * BILLION) {
+                printf("OAP request header timestamp is too new.\n");
+                goto fail_req_hdr_chk;
+        }
+
+        oap_hdr_fini(&oap_hdr);
+
+        TEST_SUCCESS();
+
+        return TEST_RC_SUCCESS;
+
+ fail_req_hdr_chk:
+        oap_hdr_fini(&oap_hdr);
+ fail_req_hdr:
+        TEST_FAIL();
+        return TEST_RC_FAIL;
+}
+
+static int test_oap_hdr_init_fini_data(void)
+
+{
+        struct oap_hdr oap_hdr;
+        buffer_t       data;
+        buffer_t       ephkey = BUF_INIT;
+        uint8_t         buf[OAP_ID_SIZE];
+        buffer_t        id;
+        void *         pkp    = NULL;
+        void *         pubcrt = NULL;
+
+        TEST_START();
+
+        random_buffer(buf, OAP_ID_SIZE);
+        id.data = buf;
+        id.len  = OAP_ID_SIZE;
+
+        data.len = 100;
+        data.data = malloc(data.len);
+        if (data.data == NULL) {
+                printf("Failed to allocate data buffer.\n");
+                goto fail_data;
+        }
+
+        random_buffer(data.data, data.len);
+
+        if (oap_hdr_init(id, pkp, pubcrt, ephkey, data, &oap_hdr) < 0) {
+                printf("Failed to create OAP request header.\n");
+                goto fail_req_hdr;
+        }
+
+        if (oap_hdr.hdr.len != OAP_HDR_MIN_SIZE + data.len) {
+                printf("OAP request header wrong: %zu < %zu.\n",
+                       oap_hdr.hdr.len, OAP_HDR_MIN_SIZE + data.len);
+                goto fail_req_hdr_sz;
+        }
+
+        oap_hdr_fini(&oap_hdr);
+
+        TEST_SUCCESS();
+
+        return TEST_RC_SUCCESS;
+
+ fail_req_hdr_sz:
+        oap_hdr_fini(&oap_hdr);
+ fail_req_hdr:
+        freebuf(data);
+ fail_data:
+        TEST_FAIL();
+        return TEST_RC_FAIL;
+}
+
+static int test_oap_hdr_init_fini_signed(void)
+{
+        struct oap_hdr oap_hdr;
+        buffer_t       ephkey = BUF_INIT;
+        buffer_t       data   = BUF_INIT;
+        buffer_t       sign;
+        buffer_t       id;
+        uint8_t        buf[OAP_ID_SIZE];
+        void *         pkp;
+        void *         pk;
+        void *         pubcrt;
+        void *         pubcrt2;
+
+        TEST_START();
+
+        random_buffer(buf, OAP_ID_SIZE);
+        id.data = buf;
+        id.len  = OAP_ID_SIZE;
+
+        if (crypt_load_privkey_str(pkp_str, &pkp) < 0) {
+                printf("Failed to load private key.\n");
+                goto fail_pkp;
+        }
+
+        if (crypt_load_crt_str(crt_str, &pubcrt) < 0) {
+                printf("Failed to load public certificate.\n");
+                goto fail_pubcrt;
+        }
+
+        if (oap_hdr_init(id, pkp, pubcrt, ephkey, data, &oap_hdr) < 0) {
+                printf("Failed to create OAP request header.\n");
+                goto fail_req_hdr;
+        }
+
+        if (crypt_load_crt_der(oap_hdr.crt, &pubcrt2) < 0) {
+                printf("Failed to load public certificate from DER.\n");
+                goto fail_crt_der;
+        }
+
+        if (crypt_get_pubkey_crt(pubcrt2, &pk) < 0) {
+                printf("Failed to get public key from certificate.\n");
+                goto fail_crt_pk;
+        }
+
+        sign = oap_hdr.hdr;
+        sign.len -= (oap_hdr.sig.len + sizeof(uint16_t));
+
+        if (auth_verify_sig(pk, sign, oap_hdr.sig) < 0) {
+                printf("Failed to verify OAP request header signature.\n");
+                goto fail_check_sig;
+        }
+
+        oap_hdr_fini(&oap_hdr);
+
+        crypt_free_crt(pubcrt2);
+        crypt_free_crt(pubcrt);
+        crypt_free_key(pk);
+
+        TEST_SUCCESS();
+
+        return TEST_RC_SUCCESS;
+
+ fail_check_sig:
+        crypt_free_key(pk);
+ fail_crt_pk:
+        crypt_free_crt(pubcrt2);
+ fail_crt_der:
+        oap_hdr_fini(&oap_hdr);
+ fail_req_hdr:
+        crypt_free_crt(pubcrt);
+ fail_pubcrt:
+        crypt_free_key(pkp);
+ fail_pkp:
+        TEST_FAIL();
+        return TEST_RC_FAIL;
+}
+
+int oap_test(int    argc,
+             char **argv)
+{
+        int ret = 0;
+
+        (void) argc;
+        (void) argv;
+
+        ret |= test_oap_hdr_init_fini();
+        ret |= test_oap_hdr_init_fini_data();
+#ifdef HAVE_OPENSSL
+        ret |= test_oap_hdr_init_fini_signed();
+#else
+        (void) test_oap_hdr_init_fini_signed;
+
+        ret = TEST_RC_SKIP;
+#endif
+        return ret;
+}