diff --git a/src/s1ap/handlers/attach_authreq.c b/src/s1ap/handlers/attach_authreq.c
new file mode 100644
index 0000000..46981f3
--- /dev/null
+++ b/src/s1ap/handlers/attach_authreq.c
@@ -0,0 +1,224 @@
+/*
+ * Copyright (c) 2003-2018, Great Software Laboratory Pvt. Ltd.
+ * Copyright (c) 2017 Intel Corporation
+ * Copyright (c) 2019, Infosys Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "err_codes.h"
+#include "s1ap.h"
+#include "message_queues.h"
+#include "ipc_api.h"
+#include "main.h"
+#include "sctp_conn.h"
+#include "msgType.h"
+
+void
+buffer_copy(struct Buffer *buffer, void *value, size_t size)
+{
+	memcpy(buffer->buf + buffer->pos , value, size);
+	buffer->pos += size;
+	return;
+}
+
+/**
+* Get ProtocolIE value for Auth Request sent by mme-app
+*/
+static int
+get_authreq_protoie_value(struct proto_IE *value, struct authreq_info *g_authreqInfo)
+{
+	value->no_of_IEs = AUTH_REQ_NO_OF_IES;
+
+	value->data = (proto_IEs *) malloc(SEC_MODE_NO_OF_IES *
+			sizeof(proto_IEs));
+
+	value->data[0].val.mme_ue_s1ap_id = g_authreqInfo->ue_idx;
+	value->data[1].val.enb_ue_s1ap_id = g_authreqInfo->enb_s1ap_ue_id;
+
+	log_msg(LOG_INFO, "mme_ue_s1ap_id %d and enb_ue_s1ap_id %d\n",
+			g_authreqInfo->ue_idx, g_authreqInfo->enb_s1ap_ue_id);
+
+	/* TODO: Add enum for security header type */
+	value->data[2].val.nas.header.security_header_type = 0;
+	value->data[2].val.nas.header.proto_discriminator = EPSMobilityManagementMessages;
+	value->data[2].val.nas.header.message_type = AuthenticationRequest;
+	value->data[2].val.nas.header.nas_security_param = AUTHREQ_NAS_SECURITY_PARAM;
+
+	value->data[2].val.nas.elements = (nas_pdu_elements *)
+			malloc(AUTH_REQ_NO_OF_NAS_IES * sizeof(nas_pdu_elements));
+
+	memcpy(value->data[2].val.nas.elements[0].pduElement.rand,
+			g_authreqInfo->rand, NAS_RAND_SIZE);
+	memcpy(value->data[2].val.nas.elements[1].pduElement.autn,
+			g_authreqInfo->autn, NAS_AUTN_SIZE);
+
+
+	return SUCCESS;
+}
+
+
+/**
+* Stage specific message processing.
+*/
+static int
+authreq_processing(struct authreq_info *g_authreqInfo)
+{
+	struct Buffer g_buffer;
+	struct Buffer g_value_buffer;
+	struct Buffer g_nas_buffer;
+
+	struct s1ap_PDU s1apPDU= {0};
+
+	/* Assigning values to s1apPDU */
+	s1apPDU.procedurecode = id_downlinkNASTransport;
+	s1apPDU.criticality = CRITICALITY_IGNORE;
+
+	get_authreq_protoie_value(&s1apPDU.value, g_authreqInfo);
+
+	/* Copy values to buffer from s1apPDU */
+
+	g_buffer.pos = 0;
+
+	uint8_t initiating_message = 0; /* TODO: Add enum */
+	buffer_copy(&g_buffer, &initiating_message,
+			sizeof(initiating_message));
+
+	buffer_copy(&g_buffer, &s1apPDU.procedurecode,
+			sizeof(s1apPDU.procedurecode));
+
+	buffer_copy(&g_buffer, &s1apPDU.criticality,
+			sizeof(s1apPDU.criticality));
+
+	/* Copy values in g_value_buffer */
+	g_value_buffer.pos = 0;
+
+	/* TODO remove hardcoded values */
+	unsigned char chProtoIENo[3] = {0,0,3};
+
+	buffer_copy(&g_value_buffer, chProtoIENo, 3);
+
+	unsigned char tmpStr[4];
+	/* id-MME-UE-S1AP-ID */
+	uint16_t protocolIe_Id = id_MME_UE_S1AP_ID;
+	copyU16(tmpStr, protocolIe_Id);
+	buffer_copy(&g_value_buffer, tmpStr,
+					sizeof(protocolIe_Id));
+
+	uint8_t protocolIe_criticality = CRITICALITY_REJECT;
+	buffer_copy(&g_value_buffer, &protocolIe_criticality,
+					sizeof(protocolIe_criticality));
+
+	uint8_t datalen = 2;
+
+	/* TODO needs proper handling*/
+	unsigned char mme_ue_id[3];
+	datalen = copyU16(mme_ue_id,
+			s1apPDU.value.data[0].val.mme_ue_s1ap_id);
+	buffer_copy(&g_value_buffer, &datalen, sizeof(datalen));
+	buffer_copy(&g_value_buffer, mme_ue_id, datalen);
+
+	/* id-eNB-UE-S1AP-ID */
+
+	protocolIe_Id = id_eNB_UE_S1AP_ID;
+	copyU16(tmpStr, protocolIe_Id);
+	buffer_copy(&g_value_buffer, tmpStr,
+						sizeof(protocolIe_Id));
+
+	buffer_copy(&g_value_buffer, &protocolIe_criticality,
+					sizeof(protocolIe_criticality));
+
+
+	/* TODO needs proper handling*/
+	unsigned char enb_ue_id[3];
+	datalen = copyU16(enb_ue_id,
+			s1apPDU.value.data[1].val.enb_ue_s1ap_id);
+	buffer_copy(&g_value_buffer, &datalen, sizeof(datalen));
+	buffer_copy(&g_value_buffer, enb_ue_id, datalen);
+	//STIMER_GET_CURRENT_TP(g_attach_stats[s1apPDU.value.enb_ue_s1ap_id].esm_in);
+
+	/* id-NAS-PDU */
+	protocolIe_Id = id_NAS_PDU;
+	copyU16(tmpStr, protocolIe_Id);
+	buffer_copy(&g_value_buffer, tmpStr,
+						sizeof(protocolIe_Id));
+
+	buffer_copy(&g_value_buffer, &protocolIe_criticality,
+					sizeof(protocolIe_criticality));
+
+	struct nasPDU *nas = &(s1apPDU.value.data[2].val.nas);
+	uint8_t value = (nas->header.security_header_type) |
+			nas->header.proto_discriminator;
+
+	g_nas_buffer.pos = 0;
+
+	buffer_copy(&g_nas_buffer, &value, sizeof(value));
+
+	buffer_copy(&g_nas_buffer, &nas->header.message_type,
+						sizeof(nas->header.message_type));
+
+	buffer_copy(&g_nas_buffer, &nas->header.nas_security_param,
+						sizeof(nas->header.nas_security_param));
+
+	buffer_copy(&g_nas_buffer, 
+	     &nas->elements[0].pduElement.rand,
+	     sizeof(nas->elements[0].pduElement.rand));
+
+	datalen = 16;
+	buffer_copy(&g_nas_buffer, &datalen, sizeof(datalen));
+
+	buffer_copy(&g_nas_buffer, 
+	   &nas->elements[1].pduElement.autn,
+	   sizeof(nas->elements[1].pduElement.autn));
+
+	datalen = g_nas_buffer.pos + 1;
+	buffer_copy(&g_value_buffer, &datalen,
+						sizeof(datalen));
+
+	buffer_copy(&g_value_buffer, &g_nas_buffer.pos,
+						sizeof(g_nas_buffer.pos));
+
+
+	buffer_copy(&g_value_buffer, &g_nas_buffer,
+						g_nas_buffer.pos);
+
+	buffer_copy(&g_buffer, &g_value_buffer.pos,
+						sizeof(g_value_buffer.pos));
+
+	buffer_copy(&g_buffer, &g_value_buffer,
+						g_value_buffer.pos);
+
+	free(s1apPDU.value.data[2].val.nas.elements);
+	free(s1apPDU.value.data);
+
+	send_sctp_msg(g_authreqInfo->enb_fd, g_buffer.buf, g_buffer.pos, 1);
+
+	return SUCCESS;
+}
+
+void*
+authreq_handler(void *data)
+{
+	log_msg(LOG_INFO, "AuthReq handler.\n");
+
+	authreq_processing((struct authreq_info *)data);
+
+	return NULL;
+}