diff --git a/programs/x509/cert_req.c b/programs/x509/cert_req.c
new file mode 100644
index 0000000..d25ad4c
--- /dev/null
+++ b/programs/x509/cert_req.c
@@ -0,0 +1,453 @@
+/*
+ *  Certificate request generation
+ *
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  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.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdio.h>
+#include <stdlib.h>
+#define mbedtls_printf          printf
+#define mbedtls_exit            exit
+#define MBEDTLS_EXIT_SUCCESS    EXIT_SUCCESS
+#define MBEDTLS_EXIT_FAILURE    EXIT_FAILURE
+#endif /* MBEDTLS_PLATFORM_C */
+
+#if !defined(MBEDTLS_X509_CSR_WRITE_C) || !defined(MBEDTLS_FS_IO) ||  \
+    !defined(MBEDTLS_PK_PARSE_C) || !defined(MBEDTLS_SHA256_C) || \
+    !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C) || \
+    !defined(MBEDTLS_PEM_WRITE_C)
+int main( void )
+{
+    mbedtls_printf( "MBEDTLS_X509_CSR_WRITE_C and/or MBEDTLS_FS_IO and/or "
+            "MBEDTLS_PK_PARSE_C and/or MBEDTLS_SHA256_C and/or "
+            "MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C "
+            "not defined.\n");
+    return( 0 );
+}
+#else
+
+#include "mbedtls/x509_csr.h"
+#include "mbedtls/entropy.h"
+#include "mbedtls/ctr_drbg.h"
+#include "mbedtls/error.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DFL_FILENAME            "keyfile.key"
+#define DFL_PASSWORD            NULL
+#define DFL_DEBUG_LEVEL         0
+#define DFL_OUTPUT_FILENAME     "cert.req"
+#define DFL_SUBJECT_NAME        "CN=Cert,O=mbed TLS,C=UK"
+#define DFL_KEY_USAGE           0
+#define DFL_FORCE_KEY_USAGE     0
+#define DFL_NS_CERT_TYPE        0
+#define DFL_FORCE_NS_CERT_TYPE  0
+#define DFL_MD_ALG              MBEDTLS_MD_SHA256
+
+#define USAGE \
+    "\n usage: cert_req param=<>...\n"                  \
+    "\n acceptable parameters:\n"                       \
+    "    filename=%%s         default: keyfile.key\n"   \
+    "    password=%%s         default: NULL\n"          \
+    "    debug_level=%%d      default: 0 (disabled)\n"  \
+    "    output_file=%%s      default: cert.req\n"      \
+    "    subject_name=%%s     default: CN=Cert,O=mbed TLS,C=UK\n"   \
+    "    key_usage=%%s        default: (empty)\n"       \
+    "                        Comma-separated-list of values:\n"     \
+    "                          digital_signature\n"     \
+    "                          non_repudiation\n"       \
+    "                          key_encipherment\n"      \
+    "                          data_encipherment\n"     \
+    "                          key_agreement\n"         \
+    "                          key_cert_sign\n"  \
+    "                          crl_sign\n"              \
+    "    force_key_usage=0/1  default: off\n"           \
+    "                          Add KeyUsage even if it is empty\n"  \
+    "    ns_cert_type=%%s     default: (empty)\n"       \
+    "                        Comma-separated-list of values:\n"     \
+    "                          ssl_client\n"            \
+    "                          ssl_server\n"            \
+    "                          email\n"                 \
+    "                          object_signing\n"        \
+    "                          ssl_ca\n"                \
+    "                          email_ca\n"              \
+    "                          object_signing_ca\n"     \
+    "    force_ns_cert_type=0/1 default: off\n"         \
+    "                          Add NsCertType even if it is empty\n"    \
+    "    md=%%s               default: SHA256\n"       \
+    "                          possible values:\n"     \
+    "                          MD4, MD5, SHA1\n"       \
+    "                          SHA224, SHA256\n"       \
+    "                          SHA384, SHA512\n"       \
+    "\n"
+
+#if defined(MBEDTLS_CHECK_PARAMS)
+void mbedtls_param_failed( const char *failure_condition,
+                           const char *file,
+                           int line )
+{
+    mbedtls_printf( "%s:%i: Input param failed - %s\n",
+                    file, line, failure_condition );
+    mbedtls_exit( MBEDTLS_EXIT_FAILURE );
+}
+#endif
+
+/*
+ * global options
+ */
+struct options
+{
+    const char *filename;       /* filename of the key file             */
+    const char *password;       /* password for the key file            */
+    int debug_level;            /* level of debugging                   */
+    const char *output_file;    /* where to store the constructed key file  */
+    const char *subject_name;   /* subject name for certificate request */
+    unsigned char key_usage;    /* key usage flags                      */
+    int force_key_usage;        /* Force adding the KeyUsage extension  */
+    unsigned char ns_cert_type; /* NS cert type                         */
+    int force_ns_cert_type;     /* Force adding NsCertType extension    */
+    mbedtls_md_type_t md_alg;   /* Hash algorithm used for signature.   */
+} opt;
+
+int write_certificate_request( mbedtls_x509write_csr *req, const char *output_file,
+                               int (*f_rng)(void *, unsigned char *, size_t),
+                               void *p_rng )
+{
+    int ret;
+    FILE *f;
+    unsigned char output_buf[4096];
+    size_t len = 0;
+
+    memset( output_buf, 0, 4096 );
+    if( ( ret = mbedtls_x509write_csr_pem( req, output_buf, 4096, f_rng, p_rng ) ) < 0 )
+        return( ret );
+
+    len = strlen( (char *) output_buf );
+
+    if( ( f = fopen( output_file, "w" ) ) == NULL )
+        return( -1 );
+
+    if( fwrite( output_buf, 1, len, f ) != len )
+    {
+        fclose( f );
+        return( -1 );
+    }
+
+    fclose( f );
+
+    return( 0 );
+}
+
+int main( int argc, char *argv[] )
+{
+    int ret = 1;
+    int exit_code = MBEDTLS_EXIT_FAILURE;
+    mbedtls_pk_context key;
+    char buf[1024];
+    int i;
+    char *p, *q, *r;
+    mbedtls_x509write_csr req;
+    mbedtls_entropy_context entropy;
+    mbedtls_ctr_drbg_context ctr_drbg;
+    const char *pers = "csr example app";
+
+    /*
+     * Set to sane values
+     */
+    mbedtls_x509write_csr_init( &req );
+    mbedtls_pk_init( &key );
+    mbedtls_ctr_drbg_init( &ctr_drbg );
+    memset( buf, 0, sizeof( buf ) );
+
+    if( argc == 0 )
+    {
+    usage:
+        mbedtls_printf( USAGE );
+        goto exit;
+    }
+
+    opt.filename            = DFL_FILENAME;
+    opt.password            = DFL_PASSWORD;
+    opt.debug_level         = DFL_DEBUG_LEVEL;
+    opt.output_file         = DFL_OUTPUT_FILENAME;
+    opt.subject_name        = DFL_SUBJECT_NAME;
+    opt.key_usage           = DFL_KEY_USAGE;
+    opt.force_key_usage     = DFL_FORCE_KEY_USAGE;
+    opt.ns_cert_type        = DFL_NS_CERT_TYPE;
+    opt.force_ns_cert_type  = DFL_FORCE_NS_CERT_TYPE;
+    opt.md_alg              = DFL_MD_ALG;
+
+    for( i = 1; i < argc; i++ )
+    {
+
+        p = argv[i];
+        if( ( q = strchr( p, '=' ) ) == NULL )
+            goto usage;
+        *q++ = '\0';
+
+        if( strcmp( p, "filename" ) == 0 )
+            opt.filename = q;
+        else if( strcmp( p, "password" ) == 0 )
+            opt.password = q;
+        else if( strcmp( p, "output_file" ) == 0 )
+            opt.output_file = q;
+        else if( strcmp( p, "debug_level" ) == 0 )
+        {
+            opt.debug_level = atoi( q );
+            if( opt.debug_level < 0 || opt.debug_level > 65535 )
+                goto usage;
+        }
+        else if( strcmp( p, "subject_name" ) == 0 )
+        {
+            opt.subject_name = q;
+        }
+        else if( strcmp( p, "md" ) == 0 )
+        {
+            if( strcmp( q, "SHA256" ) == 0 )
+            {
+                opt.md_alg = MBEDTLS_MD_SHA256;
+            }
+            else if( strcmp( q, "SHA224" ) == 0 )
+            {
+                opt.md_alg = MBEDTLS_MD_SHA224;
+            }
+            else
+#if defined(MBEDTLS_MD5_C)
+            if( strcmp( q, "MD5" ) == 0 )
+            {
+                opt.md_alg = MBEDTLS_MD_MD5;
+            }
+            else
+#endif /* MBEDTLS_MD5_C */
+#if defined(MBEDTLS_MD4_C)
+            if( strcmp( q, "MD4" ) == 0 )
+            {
+                opt.md_alg = MBEDTLS_MD_MD4;
+            }
+            else
+#endif /* MBEDTLS_MD5_C */
+#if defined(MBEDTLS_SHA1_C)
+            if( strcmp( q, "SHA1" ) == 0 )
+            {
+                opt.md_alg = MBEDTLS_MD_SHA1;
+            }
+            else
+#endif /* MBEDTLS_SHA1_C */
+#if defined(MBEDTLS_SHA512_C)
+            if( strcmp( q, "SHA384" ) == 0 )
+            {
+                opt.md_alg = MBEDTLS_MD_SHA384;
+            }
+            else
+            if( strcmp( q, "SHA512" ) == 0 )
+            {
+                opt.md_alg = MBEDTLS_MD_SHA512;
+            }
+            else
+#endif /* MBEDTLS_SHA512_C */
+            {
+                goto usage;
+            }
+        }
+        else if( strcmp( p, "key_usage" ) == 0 )
+        {
+            while( q != NULL )
+            {
+                if( ( r = strchr( q, ',' ) ) != NULL )
+                    *r++ = '\0';
+
+                if( strcmp( q, "digital_signature" ) == 0 )
+                    opt.key_usage |= MBEDTLS_X509_KU_DIGITAL_SIGNATURE;
+                else if( strcmp( q, "non_repudiation" ) == 0 )
+                    opt.key_usage |= MBEDTLS_X509_KU_NON_REPUDIATION;
+                else if( strcmp( q, "key_encipherment" ) == 0 )
+                    opt.key_usage |= MBEDTLS_X509_KU_KEY_ENCIPHERMENT;
+                else if( strcmp( q, "data_encipherment" ) == 0 )
+                    opt.key_usage |= MBEDTLS_X509_KU_DATA_ENCIPHERMENT;
+                else if( strcmp( q, "key_agreement" ) == 0 )
+                    opt.key_usage |= MBEDTLS_X509_KU_KEY_AGREEMENT;
+                else if( strcmp( q, "key_cert_sign" ) == 0 )
+                    opt.key_usage |= MBEDTLS_X509_KU_KEY_CERT_SIGN;
+                else if( strcmp( q, "crl_sign" ) == 0 )
+                    opt.key_usage |= MBEDTLS_X509_KU_CRL_SIGN;
+                else
+                    goto usage;
+
+                q = r;
+            }
+        }
+        else if( strcmp( p, "force_key_usage" ) == 0 )
+        {
+            switch( atoi( q ) )
+            {
+                case 0: opt.force_key_usage = 0; break;
+                case 1: opt.force_key_usage = 1; break;
+                default: goto usage;
+            }
+        }
+        else if( strcmp( p, "ns_cert_type" ) == 0 )
+        {
+            while( q != NULL )
+            {
+                if( ( r = strchr( q, ',' ) ) != NULL )
+                    *r++ = '\0';
+
+                if( strcmp( q, "ssl_client" ) == 0 )
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_SSL_CLIENT;
+                else if( strcmp( q, "ssl_server" ) == 0 )
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER;
+                else if( strcmp( q, "email" ) == 0 )
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_EMAIL;
+                else if( strcmp( q, "object_signing" ) == 0 )
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_OBJECT_SIGNING;
+                else if( strcmp( q, "ssl_ca" ) == 0 )
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_SSL_CA;
+                else if( strcmp( q, "email_ca" ) == 0 )
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_EMAIL_CA;
+                else if( strcmp( q, "object_signing_ca" ) == 0 )
+                    opt.ns_cert_type |= MBEDTLS_X509_NS_CERT_TYPE_OBJECT_SIGNING_CA;
+                else
+                    goto usage;
+
+                q = r;
+            }
+        }
+        else if( strcmp( p, "force_ns_cert_type" ) == 0 )
+        {
+            switch( atoi( q ) )
+            {
+                case 0: opt.force_ns_cert_type = 0; break;
+                case 1: opt.force_ns_cert_type = 1; break;
+                default: goto usage;
+            }
+        }
+        else
+            goto usage;
+    }
+
+    mbedtls_x509write_csr_set_md_alg( &req, opt.md_alg );
+
+    if( opt.key_usage || opt.force_key_usage == 1 )
+        mbedtls_x509write_csr_set_key_usage( &req, opt.key_usage );
+
+    if( opt.ns_cert_type || opt.force_ns_cert_type == 1 )
+        mbedtls_x509write_csr_set_ns_cert_type( &req, opt.ns_cert_type );
+
+    /*
+     * 0. Seed the PRNG
+     */
+    mbedtls_printf( "  . Seeding the random number generator..." );
+    fflush( stdout );
+
+    mbedtls_entropy_init( &entropy );
+    if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
+                               (const unsigned char *) pers,
+                               strlen( pers ) ) ) != 0 )
+    {
+        mbedtls_printf( " failed\n  !  mbedtls_ctr_drbg_seed returned %d", ret );
+        goto exit;
+    }
+
+    mbedtls_printf( " ok\n" );
+
+    /*
+     * 1.0. Check the subject name for validity
+     */
+    mbedtls_printf( "  . Checking subject name..." );
+    fflush( stdout );
+
+    if( ( ret = mbedtls_x509write_csr_set_subject_name( &req, opt.subject_name ) ) != 0 )
+    {
+        mbedtls_printf( " failed\n  !  mbedtls_x509write_csr_set_subject_name returned %d", ret );
+        goto exit;
+    }
+
+    mbedtls_printf( " ok\n" );
+
+    /*
+     * 1.1. Load the key
+     */
+    mbedtls_printf( "  . Loading the private key ..." );
+    fflush( stdout );
+
+    ret = mbedtls_pk_parse_keyfile( &key, opt.filename, opt.password );
+
+    if( ret != 0 )
+    {
+        mbedtls_printf( " failed\n  !  mbedtls_pk_parse_keyfile returned %d", ret );
+        goto exit;
+    }
+
+    mbedtls_x509write_csr_set_key( &req, &key );
+
+    mbedtls_printf( " ok\n" );
+
+    /*
+     * 1.2. Writing the request
+     */
+    mbedtls_printf( "  . Writing the certificate request ..." );
+    fflush( stdout );
+
+    if( ( ret = write_certificate_request( &req, opt.output_file,
+                                           mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
+    {
+        mbedtls_printf( " failed\n  !  write_certifcate_request %d", ret );
+        goto exit;
+    }
+
+    mbedtls_printf( " ok\n" );
+
+    exit_code = MBEDTLS_EXIT_SUCCESS;
+
+exit:
+
+    if( exit_code != MBEDTLS_EXIT_SUCCESS )
+    {
+#ifdef MBEDTLS_ERROR_C
+        mbedtls_strerror( ret, buf, sizeof( buf ) );
+        mbedtls_printf( " - %s\n", buf );
+#else
+        mbedtls_printf("\n");
+#endif
+    }
+
+    mbedtls_x509write_csr_free( &req );
+    mbedtls_pk_free( &key );
+    mbedtls_ctr_drbg_free( &ctr_drbg );
+    mbedtls_entropy_free( &entropy );
+
+#if defined(_WIN32)
+    mbedtls_printf( "  + Press Enter to exit this program.\n" );
+    fflush( stdout ); getchar();
+#endif
+
+    return( exit_code );
+}
+#endif /* MBEDTLS_X509_CSR_WRITE_C && MBEDTLS_PK_PARSE_C && MBEDTLS_FS_IO &&
+          MBEDTLS_ENTROPY_C && MBEDTLS_CTR_DRBG_C && MBEDTLS_PEM_WRITE_C */