Guide for building an ECC pki
draft-moskowitz-ecdsa-pki-01

Versions: 00 01                                                         
wg TBD                                                      R. Moskowitz
Internet-Draft                                                    Huawei
Intended status: Informational                               H. Birkholz
Expires: March 11, 2018                                   Fraunhofer SIT
                                                                  L. Xia
                                                                  Huawei
                                                       September 7, 2017


                     Guide for building an ECC pki
                      draft-moskowitz-ecdsa-pki-01

Abstract

   This memo provides a guide for building a PKI (Public Key
   Infrastructure) using openSSL.  All certificates in this guide are
   ECDSA, P-256, with SHA256 certificates.  Along with common End Entity
   certificates, this guide provides instructions for creating IEEE
   802.1AR iDevID Secure Device certificates.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 11, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terms and Definitions . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Requirements Terminology  . . . . . . . . . . . . . . . .   3
     2.2.  Notations . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.3.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  The Basic PKI feature set . . . . . . . . . . . . . . . . . .   4
   4.  Getting started and the Root level  . . . . . . . . . . . . .   4
     4.1.  Setting up the Environment  . . . . . . . . . . . . . . .   5
     4.2.  Create the Root Certificate . . . . . . . . . . . . . . .   6
   5.  The Intermediate level  . . . . . . . . . . . . . . . . . . .   7
     5.1.  Setting up the Intermediate Certificate Environment . . .   7
     5.2.  Create the Intermediate Certificate . . . . . . . . . . .   7
     5.3.  Create a Server EE Certificate  . . . . . . . . . . . . .   9
     5.4.  Create a Client EE Certificate  . . . . . . . . . . . . .   9
   6.  The 802.1AR Intermediate level  . . . . . . . . . . . . . . .  10
     6.1.  Setting up the 802.1AR Intermediate Certificate
           Environment . . . . . . . . . . . . . . . . . . . . . . .  10
     6.2.  Create the 802.1AR Intermediate Certificate . . . . . . .  11
     6.3.  Create an 802.1AR iDevID Certificate  . . . . . . . . . .  13
   7.  Setting up a CRL for an Intermediate CA . . . . . . . . . . .  14
     7.1.  Create (or recreate) the CRL  . . . . . . . . . . . . . .  14
     7.2.  Revoke a Certificate  . . . . . . . . . . . . . . . . . .  14
   8.  Setting up OCSP for an Intermediate CA  . . . . . . . . . . .  15
     8.1.  Create the OCSP Certificate . . . . . . . . . . . . . . .  15
     8.2.  Revoke a Certificate  . . . . . . . . . . . . . . . . . .  17
     8.3.  Testing OCSP with Openssl . . . . . . . . . . . . . . . .  17
   9.  Footnotes . . . . . . . . . . . . . . . . . . . . . . . . . .  17
     9.1.  Certificate Serial Number . . . . . . . . . . . . . . . .  18
     9.2.  Some OpenSSL config file limitations  . . . . . . . . . .  18
     9.3.  subjectAltName support, or lack thereof . . . . . . . . .  19
     9.4.  DER support, or lack thereof  . . . . . . . . . . . . . .  19
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  20
     11.1.  Adequate Randomness  . . . . . . . . . . . . . . . . . .  20
     11.2.  Key pair Theft . . . . . . . . . . . . . . . . . . . . .  20
   12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  20
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  21
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  21
     13.2.  Informative References . . . . . . . . . . . . . . . . .  21
   Appendix A.  OpenSSL config files . . . . . . . . . . . . . . . .  21
     A.1.  OpenSSL Root config file  . . . . . . . . . . . . . . . .  21
     A.2.  OpenSSL Intermediate config file  . . . . . . . . . . . .  24



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     A.3.  OpenSSL 802.1AR Intermediate config file  . . . . . . . .  27
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  30

1.  Introduction

   The IETF has a plethora of security solutions targeted at IoT.  Yet
   all too many IoT products are deployed with no or improperly
   configured security.  In particular resource constrained IoT devices
   and non-IP IoT networks have not been well served in the IETF.

   Additionally, more IETF (e.g.  DOTS, NETCONF) efforts are requiring
   secure identities, but are vague on the nature of these identities
   other than to recommend use of X.509 digital certificates and perhaps
   TLS.

   This effort provides the steps, using the openSSL application, to
   create such a PKI of ECDSA certificates.  The goal is that any
   developer or tester can follow these steps, create the basic objects
   needed and establish the validity of the standard/program design.
   This guide can even be used to create a production PKi, though
   additional steps need to be taken.  This could be very useful to a
   small vendor needing to include 802.1AR [IEEE.802.1AR_2009] iDevIDs
   in their product.

   This guide was tested with openSSL 1.1.0f on Fedora 26 and creates
   PEM-based certificates.  DER based certificates fails (see
   Section 9.4).

2.  Terms and Definitions

2.1.  Requirements Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.2.  Notations

   This section will contain notations

2.3.  Definitions

   TBD








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3.  The Basic PKI feature set

   A basic pki has two levels of hierarchy: Root and Intermediate.  The
   Root level has the greatest risk, and is the least used.  It only
   signs the Intermediate level signing certificate.  As such, once the
   Root level is created and signs the Intermediate level certificate it
   can be locked up.  In fact, the Root level could exist completely on
   a mSD boot card for an ARM small computer like a RaspberryPi.  A copy
   of this card came be made and securely stored in a different
   location.

   The Root level contains the Root certificate private key, a database
   of all signed certificates, and the public certificate.  It can also
   contain the Intermediate level public certificate and a Root level
   CRL.

   The Intermediate level contains the Intermediate certificate private
   key, the public certificate, a database of all signed certificates,
   the certificate trust chain, and Intermediate level CRL.  It can also
   contain the End Entity public certificates.  The private key file
   needs to be keep securely.  For example as with the Root level, a mSD
   image for an ARM computer could contain the complete Intermediate
   level.  This image is kept offline.  The End Entity CSR is copied to
   it, signed, and then the signed certificate and updated database are
   moved to the public image that lacks the private key.

   For a simple test pki, all files can be kept on a single system that
   is managed by the tester.

   End Entities create a key pair and a Certificate Signing Request
   (CSR).  The private key is stored securely.  The CSR is delivered to
   the Intermediate level which uses the CSR to create the End Entity
   certificate.  This certificate, along with the trust chain back to
   the root, is then returned to the End Entity.

   There is more to a pki, but this suffices for most development and
   testing needs.

4.  Getting started and the Root level

   This guide was developed on a Fedora 26 armv7hl system (Cubieboard2
   SoC).  It should work on most Linux and similar systems.  All work
   was done in a terminal window with extensive "cutting and pasting"
   from a draft guide into the terminal window.  Users of this guide may
   find different behaviors based on their system.






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4.1.  Setting up the Environment

   The first step is to create the pki environment.  Modify the
   variables to suit your needs.


   export dir=/root/ca
   export cadir=/root/ca
   export format=pem
   mkdir $dir
   cd $dir
   mkdir certs crl csr newcerts private
   chmod 700 private
   touch index.txt
   touch serial
   sn=8

   countryName="/C=US"
   stateOrProvinceName="/ST=MI"
   localityName="/L=Oak Park"
   organizationName="/O=HTT Consulting"
   #organizationalUnitName="/OU="
   organizationalUnitName=
   commonName="/CN=Root CA"
   DN=$countryName$stateOrProvinceName$localityName
   DN=$DN$organizationName$organizationalUnitName$commonName
   echo $DN
   export subjectAltName=email:postmaster@htt-consult.com


   Where:

   dir
            Directory for certificate files

   cadir
            Directory for Root certificate files

   Format
            File encoding: PEM or DER
            At this time only PEM works

   sn
            Serial Number length in bytes
            For a public CA the range is 8 to 19






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   The Serial Number length for a public pki ranges from 8 to 19 bytes.
   The use of 19 rather than 20 is to accommodate the hex representation
   of the Serial Number.  If it has a one in the high order bit, DER
   encoding rules will place a 0x00 in front.

   The DN and SAN fields are examples.  Change them to appropriate
   values.  If you leave one blank, it will be left out of the
   Certificate.  "OU" above is an example of an empty DN object.

   Create the file, $dir/openssl-root.cnf from the contents in
   Appendix A.1.

4.2.  Create the Root Certificate

   Next are the openssl commands to create the Root certificate keypair,
   and the Root certificate.  Included are commands to view the file
   contents.


   # Create passworded keypair file

   openssl genpkey -aes256 -algorithm ec\
       -pkeyopt ec_paramgen_curve:prime256v1\
       -outform $format -pkeyopt ec_param_enc:named_curve\
       -out $dir/private/ca.key.$format
   chmod 400 $dir/private/ca.key.$format
   openssl pkey -inform $format -in private/ca.key.$format -text -noout

   # Create Self-signed Root Certificate file
   # 7300 days = 20 years; Intermediate CA is 10 years.

   openssl req -config $dir/openssl-root.cnf\
        -set_serial 0x$(openssl rand -hex $sn)\
        -keyform $format -outform $format\
        -key $dir/private/ca.key.$format -subj "$DN"\
        -new -x509 -days 7300 -sha256 -extensions v3_ca\
        -out $dir/certs/ca.cert.$format

   #

   openssl x509 -inform $format -in $dir/certs/ca.cert.$format\
        -text -noout
   openssl x509 -purpose -inform $format\
        -in $dir/certs/ca.cert.$format -inform $format







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5.  The Intermediate level

5.1.  Setting up the Intermediate Certificate Environment

   The next part is to create the Intermediate pki environment.  Modify
   the variables to suit your needs.  In particular, set the variables
   for CRL and/or OCSP support.


   export dir=$cadir/intermediate
   mkdir $dir
   cd $dir
   mkdir certs crl csr newcerts private
   chmod 700 private
   touch index.txt
   sn=8 # hex 8 is minimum, 19 is maximum
   echo 1000 > $dir/crlnumber

   # cd $dir
   export crlDP=
   # For CRL support use uncomment these:
   #crl=intermediate.crl.pem
   #crlurl=www.htt-consult.com/pki/$crl
   #export crlDP="URI:http://$crlurl"
   export default_crl_days=30
   export ocspIAI=
   # For OCSP support use uncomment these:
   #ocspurl=ocsp.htt-consult.com
   #export ocspIAI="OCSP;URI:http://$ocspurl"

   commonName="/CN=Signing CA"
   DN=$countryName$stateOrProvinceName$localityName$organizationName
   DN=$DN$organizationalUnitName$commonName
   echo $DN


   Create the file, $dir/openssl-intermediate.cnf from the contents in
   Appendix A.2.

5.2.  Create the Intermediate Certificate

   Here are the openssl commands to create the Intermediate certificate
   keypair, Intermediate certificate signed request (CSR), and the
   Intermediate certificate.  Included are commands to view the file
   contents.






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   # Create passworded keypair file

   openssl genpkey -aes256 -algorithm ec\
       -pkeyopt ec_paramgen_curve:prime256v1 \
       -outform $format -pkeyopt ec_param_enc:named_curve\
       -out $dir/private/intermediate.key.$format
   chmod 400 $dir/private/intermediate.key.$format
   openssl pkey -inform $format\
       -in $dir/private/intermediate.key.$format -text -noout

   # Create the CSR

   openssl req -config $cadir/openssl-root.cnf\
       -key $dir/private/intermediate.key.$format \
       -keyform $format -outform $format -subj "$DN" -new -sha256\
       -out $dir/csr/intermediate.csr.$format
   openssl req -text -noout -verify -inform $format\
       -in $dir/csr/intermediate.csr.$format


   # Create Intermediate Certificate file

   openssl rand -hex $sn > $dir/serial # hex 8 is minimum, 19 is maximum
   # Note 'openssl ca' does not support DER format
   openssl ca -config $cadir/openssl-root.cnf -days 3650\
       -extensions v3_intermediate_ca -notext -md sha256 \
       -in $dir/csr/intermediate.csr.$format\
       -out $dir/certs/intermediate.cert.pem

   chmod 444 $dir/certs/intermediate.cert.$format

   openssl verify -CAfile $cadir/certs/ca.cert.$format\
        $dir/certs/intermediate.cert.$format

   openssl x509 -noout -text -in $dir/certs/intermediate.cert.$format

   # Create the certificate chain file

   cat $dir/certs/intermediate.cert.$format\
      $cadir/certs/ca.cert.$format > $dir/certs/ca-chain.cert.$format
   chmod 444 $dir/certs/ca-chain.cert.$format










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5.3.  Create a Server EE Certificate

   Here are the openssl commands to create a Server End Entity
   certificate keypair, Server certificate signed request (CSR), and the
   Server certificate.  Included are commands to view the file contents.


   commonName=
   DN=$countryName$stateOrProvinceName$localityName
   DN=$DN$organizationName$organizationalUnitName$commonName
   echo $DN
   serverfqdn=www.example.com
   emailaddr=postmaster@htt-consult.com
   export subjectAltName="DNS:$serverfqdn, email:$emailaddr"
   echo $subjectAltName
   openssl genpkey -algorithm ec -pkeyopt ec_paramgen_curve:prime256v1\
       -pkeyopt ec_param_enc:named_curve\
       -out $dir/private/$serverfqdn.key.$format
   chmod 400 $dir/private/$serverfqdn.$format
   openssl pkey -in $dir/private/$serverfqdn.key.$format -text -noout
   openssl req -config $dir/openssl-intermediate.cnf\
       -key $dir/private/$serverfqdn.key.$format \
       -subj "$DN" -new -sha256 -out $dir/csr/$serverfqdn.csr.$format

   openssl req -text -noout -verify -in $dir/csr/$serverfqdn.csr.$format

   openssl rand -hex $sn > $dir/serial # hex 8 is minimum, 19 is maximum
   # Note 'openssl ca' does not support DER format
   openssl ca -config $dir/openssl-intermediate.cnf -days 375\
       -extensions server_cert -notext -md sha256 \
       -in $dir/csr/$serverfqdn.csr.$format\
       -out $dir/certs/$serverfqdn.cert.$format
   chmod 444 $dir/certs/$serverfqdn.cert.$format

   openssl verify -CAfile $dir/certs/ca-chain.cert.$format\
        $dir/certs/$serverfqdn.cert.$format
   openssl x509 -noout -text -in $dir/certs/$serverfqdn.cert.$format


5.4.  Create a Client EE Certificate

   Here are the openssl commands to create a Client End Entity
   certificate keypair, Client certificate signed request (CSR), and the
   Client certificate.  Included are commands to view the file contents.







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   commonName=
   UserID="/UID=rgm"
   DN=$countryName$stateOrProvinceName$localityName
   DN=$DN$organizationName$organizationalUnitName$commonName$UserID
   echo $DN
   clientemail=rgm@example.com
   export subjectAltName="email:$clientemail"
   echo $subjectAltName
   openssl genpkey -algorithm ec -pkeyopt ec_paramgen_curve:prime256v1\
       -pkeyopt ec_param_enc:named_curve\
       -out $dir/private/$clientemail.key.$format
   chmod 400 $dir/private/$clientemail.$format
   openssl pkey -in $dir/private/$clientemail.key.$format -text -noout
   openssl req -config $dir/openssl-intermediate.cnf\
       -key $dir/private/$clientemail.key.$format \
       -subj "$DN" -new -sha256 -out $dir/csr/$clientemail.csr.$format

   openssl req -text -noout -verify\
       -in $dir/csr/$clientemail.csr.$format

   openssl rand -hex $sn > $dir/serial # hex 8 is minimum, 19 is maximum
   # Note 'openssl ca' does not support DER format
   openssl ca -config $dir/openssl-intermediate.cnf -days 375\
       -extensions usr_cert -notext -md sha256 \
       -in $dir/csr/$clientemail.csr.$format\
       -out $dir/certs/$clientemail.cert.$format
   chmod 444 $dir/certs/$clientemail.cert.$format

   openssl verify -CAfile $dir/certs/ca-chain.cert.$format\
        $dir/certs/$clientemail.cert.$format
   openssl x509 -noout -text -in $dir/certs/$clientemail.cert.$format


6.  The 802.1AR Intermediate level

6.1.  Setting up the 802.1AR Intermediate Certificate Environment

   The next part is to create the 802.1AR Intermediate pki environment.
   This is very similar to the Intermediate pki environment.  Modify the
   variables to suit your needs.











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   export dir=$cadir/8021ARintermediate
   mkdir $dir
   cd $dir
   mkdir certs crl csr newcerts private
   chmod 700 private
   touch index.txt
   sn=8 # hex 8 is minimum, 19 is maximum
   echo 1000 > $dir/crlnumber

   # cd $dir
   export crlDP=
   # For CRL support use uncomment these:
   #crl=8021ARintermediate.crl.pem
   #crlurl=www.htt-consult.com/pki/$crl
   #export crlDP="URI:http://$crlurl"
   export default_crl_days=30
   export ocspIAI=
   # For OCSP support use uncomment these:
   #ocspurl=ocsp.htt-consult.com
   #export ocspIAI="OCSP;URI:http://$ocspurl"

   countryName="/C=US"
   stateOrProvinceName="/ST=MI"
   localityName="/L=Oak Park"
   organizationName="/O=HTT Consulting"
   organizationalUnitName="/OU=Devices"
   #organizationalUnitName=
   commonName="/CN=802.1AR CA"
   DN=$countryName$stateOrProvinceName$localityName$organizationName
   DN=$DN$organizationalUnitName$commonName
   echo $DN
   export subjectAltName=email:postmaster@htt-consult.com
   echo $subjectAltName


   Create the file, $dir/openssl-8021ARintermediate.cnf from the
   contents in Appendix A.3.

6.2.  Create the 802.1AR Intermediate Certificate

   Here are the openssl commands to create the 802.1AR Intermediate
   certificate keypair, 802.1AR Intermediate certificate signed request
   (CSR), and the 802.1AR Intermediate certificate.  Included are
   commands to view the file contents.







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   # Create passworded keypair file

   openssl genpkey -aes256 -algorithm ec\
       -pkeyopt ec_paramgen_curve:prime256v1 \
       -outform $format -pkeyopt ec_param_enc:named_curve\
       -out $dir/private/8021ARintermediate.key.$format
   chmod 400 $dir/private/8021ARintermediate.key.$format
   openssl pkey -inform $format\
       -in $dir/private/8021ARintermediate.key.$format -text -noout

   # Create the CSR

   openssl req -config $cadir/openssl-root.cnf\
       -key $dir/private/8021ARintermediate.key.$format \
       -keyform $format -outform $format -subj "$DN" -new -sha256\
       -out $dir/csr/8021ARintermediate.csr.$format
   openssl req -text -noout -verify -inform $format\
       -in $dir/csr/8021ARintermediate.csr.$format


   # Create 802.1AR Intermediate Certificate file
   # The following does NOT work for DER

   openssl rand -hex $sn > $dir/serial # hex 8 is minimum, 19 is maximum
   # Note 'openssl ca' does not support DER format
   openssl ca -config $cadir/openssl-root.cnf -days 3650\
       -extensions v3_intermediate_ca -notext -md sha256\
       -in $dir/csr/8021ARintermediate.csr.$format\
       -out $dir/certs/8021ARintermediate.cert.pem

   chmod 444 $dir/certs/8021ARintermediate.cert.$format

   openssl verify -CAfile $cadir/certs/ca.cert.$format\
        $dir/certs/8021ARintermediate.cert.$format

   openssl x509 -noout -text\
        -in $dir/certs/8021ARintermediate.cert.$format

   # Create the certificate chain file

   cat $dir/certs/8021ARintermediate.cert.$format\
      $cadir/certs/ca.cert.$format > $dir/certs/ca-chain.cert.$format
   chmod 444 $dir/certs/ca-chain.cert.$format








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6.3.  Create an 802.1AR iDevID Certificate

   Here are the openssl commands to create a 802.1AR iDevID certificate
   keypair, iDevID certificate signed request (CSR), and the iDevID
   certificate.  Included are commands to view the file contents.


   DevID=Wt1234
   countryName=
   stateOrProvinceName=
   localityName=
   organizationName="/O=HTT Consulting"
   organizationalUnitName="/OU=Devices"
   commonName=
   serialNumber="/serialNumber=$DevID"
   DN=$countryName$stateOrProvinceName$localityName
   DN=$DN$organizationName$organizationalUnitName$commonName
   DN=$DN$serialNumber
   echo $DN

   # hwType is OID for HTT Consulting, devices, sensor widgets
   export hwType=1.3.6.1.4.1.6715.10.1
   export hwSerialNum=01020304 # Some hex
   export subjectAltName="otherName:1.3.6.1.5.5.7.8.4;SEQ:hmodname"
   echo  $hwType - $hwSerialNum

   openssl genpkey -algorithm ec -pkeyopt ec_paramgen_curve:prime256v1\
       -pkeyopt ec_param_enc:named_curve\
       -out $dir/private/$DevID.key.$format
   chmod 400 $dir/private/$DevID.$format
   openssl pkey -in $dir/private/$DevID.key.$format -text -noout
   openssl req -config $dir/openssl-8021ARintermediate.cnf\
       -key $dir/private/$DevID.key.$format \
       -subj "$DN" -new -sha256 -out $dir/csr/$DevID.csr.$format

   openssl req -text -noout -verify\
       -in $dir/csr/$DevID.csr.$format
   openssl asn1parse -i -in $dir/csr/$DevID.csr.pem
   # offset of start of hardwareModuleName and use that in place of 189
   openssl asn1parse -i -strparse 189 -in $dir/csr/$DevID.csr.pem

   openssl rand -hex $sn > $dir/serial # hex 8 is minimum, 19 is maximum
   # Note 'openssl ca' does not support DER format
   openssl ca -config $dir/openssl-8021ARintermediate.cnf -days 375\
       -extensions 8021ar_idevid -notext -md sha256 \
       -in $dir/csr/$DevID.csr.$format\
       -out $dir/certs/$DevID.cert.$format
   chmod 444 $dir/certs/$DevID.cert.$format



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   openssl verify -CAfile $dir/certs/ca-chain.cert.$format\
        $dir/certs/$DevID.cert.$format
   openssl x509 -noout -text -in $dir/certs/$DevID.cert.$format
   openssl asn1parse -i -in $dir/certs/$DevID.cert.pem

   # offset of start of hardwareModuleName and use that in place of 493
   openssl asn1parse -i -strparse 493 -in $dir/certs/$DevID.cert.pem


7.  Setting up a CRL for an Intermediate CA

   This part provides CRL support to an Intermediate CA.  In this memo
   it applies to both Intermediate CAs.  Set the crlDistributionPoints
   as provided via the environment variables.

7.1.  Create (or recreate) the CRL

   It is simple to create the CRL.  The CRL consists of the certificates
   flagged with an R (Revoked) in index.txt:


   # Select which Intermediate level
   intermediate=intermediate
   #intermediate=8021ARintermediate

   # Create CRL file
   openssl ca -config $dir/openssl-$intermediate.cnf \
         -gencrl -out $dir/crl/$crl
   chmod 444 $dir/crl/$crl

   openssl crl -in $dir/crl/$crl -noout -text


7.2.  Revoke a Certificate

   Revoking a certificate is a two step process.  First identify the
   target certificate.  Revoke it then publish a new CRL.


   targetcert=fqdn
   #targetcert=clientemail
   #targetcert=DevID

   openssl ca -config $dir/openssl-$intermediate.cnf\
    -revoke $dir/certs/$targetcert.cert.$format


   Recreate the CRL using Section 7.1.



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8.  Setting up OCSP for an Intermediate CA

   This part provides OCSP support to an Intermediate CA.  In this memo
   it applies to both Intermediate CAs.  Set the authorityInfoAccess as
   provided via the environment variables.

8.1.  Create the OCSP Certificate

   OCSP needs a signing certificate.  This certificate must be signed by
   the CA that signed the certificate being checked.  The steps to
   create this certificate is the similar to a Server certificate for
   the CA:







































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   # Select which Intermediate level
   intermediate=intermediate
   #intermediate=8021AR
   # Optionally, password encrypt key pair
   encryptkey=
   #encryptkey=-aes256

   # Create the key pair in Intermediate level $intermediate
   cd $dir
   openssl genpkey -algorithm ec -pkeyopt ec_paramgen_curve:prime256v1\
       $encryptkey -pkeyopt ec_param_enc:named_curve\
       -out $dir/private/$ocspurl.key.$format
   chmod 400 $dir/private/$ocspurl.$format
   openssl pkey -in $dir/private/$ocspurl.key.$format -text -noout

   # Create CSR
   commonName=
   DN=$countryName$stateOrProvinceName$localityName
   DN=$DN$organizationName$organizationalUnitName$commonName
   echo $DN
   emailaddr=postmaster@htt-consult.com
   export subjectAltName="DNS:$ocspurl, email:$emailaddr"
   echo $subjectAltName
   openssl req -config $dir/openssl-$intermediate.cnf\
       -key $dir/private/$ocspurl.key.$format \
       -subj "$DN" -new -sha256 -out $dir/csr/$ocspurl.csr.$format

   openssl req -text -noout -verify -in $dir/csr/$ocspurl.csr.$format

   # Create Certificate

   openssl rand -hex $sn > $dir/serial # hex 8 is minimum, 19 is maximum
   # Note 'openssl ca' does not support DER format
   openssl ca -config $dir/openssl-$intermediate.cnf -days 375\
       -extensions ocsp -notext -md sha256 \
       -in $dir/csr/$ocspurl.csr.$format\
       -out $dir/certs/$ocspurl.cert.$format
   chmod 444 $dir/certs/$ocspurl.cert.$format

   openssl verify -CAfile $dir/certs/ca-chain.cert.$format\
        $dir/certs/$ocspurl.cert.$format
   openssl x509 -noout -text -in $dir/certs/$ocspurl.cert.$format









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8.2.  Revoke a Certificate

   Revoke the certificate as in Section 7.2.  The OCSP responder SHOULD
   detect the flag change in index.txt and, when queried respond
   appropriately.

8.3.  Testing OCSP with Openssl

   OpenSSL provides a simple OCSP service that can be used to test the
   OCSP certificate and revocation process (Note that this only reads
   the index.txt to get the certificate status at startup).

   In a terminal window run:


   openssl ocsp -port 2560 -text -rmd sha256\
         -index $dir/index.txt \
         -CA $dir/certs/ca-chain.cert.pem \
         -rkey $dir/private/$ocspurl.key.pem \
         -rsigner $dir/certs/$ocspurl.cert.pem \
         -nrequest 1


   In another window, test out a certificate status with:


   targetcert=fqdn
   #targetcert=clientemail
   #targetcert=DevID

   openssl ocsp -CAfile $dir/certs/ca-chain.cert.pem \
         -url http://127.0.0.1:2560 -resp_text \
         -issuer $dir/certs/$intermediate.cert.pem \
         -cert $dir/certs/$targetcert.cert.pem


   Revoke the certificate, Section 7.2, restart the test Responder again
   as above, then check the certificate status.

9.  Footnotes

   Creating this document was a real education in the state of openSSL,
   X.509 certificate guidance, and just general level of certificate
   awareness.  Here are a few short notes.







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9.1.  Certificate Serial Number

   The certificate serial number's role is to provide yet another way to
   maintain uniqueness of certificates within a pki as well as a way to
   index them in a data store.  It has taken on other roles, most
   notably as a defense.

   The CABForum guideline for a public CA is for the serial number to be
   a random number at least 8 octets long and no longer than 20 bytes.
   By default, openssl makes self-signed certificates with 8 octet
   serial numbers.  This guide uses openssl's RAND function to generate
   the random value and pipe it into the -set_serial option.  This
   number MAY have the first bit as a ONE; the DER encoding rules
   prepend such numbers with 0x00.  Thus the limit of '19' for the
   variable 'ns'.

   A private CA need not follow the CABForum rules and can use anything
   number for the serial number.  For example, the root CA (which has no
   security risks mitigated by using a random value) could use '1' as
   its serial number.  Intermediate and End Entity certificate serial
   numbers can also be of any value if a strong hash, like SHA256 used
   here.  A value of 4 for ns would provide a sufficient population so
   that a CA of 10,000 EE certificates will have only a 1.2% probability
   of a collision.  For only 1,000 certificates the probability drops to
   0.012%.

   The following was proposed on the openssl-user list as an alternative
   to using the RAND function:

   Keep k bits (k/8 octets) long serial numbers for all your
   certificates, chose a block cipher operating on blocks of k bits, and
   operate this block cipher in CTR mode, with a proper secret key and
   secret starting counter.  That way, no collision detection is
   necessary, you'll be able to generate 2^(k/2) unique k bits longs
   serial numbers (in fact, you can generate 2^k unique serial numbers,
   but after 2^(k/2) you lose some security guarantees).

   With 3DES, k=64, and with AES, k=128.

9.2.  Some OpenSSL config file limitations

   There is a bit of inconsistency in how different parts and fields in
   the config file are used.  Environment variables can only be used as
   values.  Some fields can have null values, others cannot.  The lack
   of allowing null fields means a script cannot feed in an environment
   variable with value null.  In such a case, the field has to be
   removed from the config file.




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   The expectation is each CA within a PKI has its own config file,
   customized to the certificates supported by that CA.

9.3.  subjectAltName support, or lack thereof

   There is no direct openssl command line option to provide a
   subjectAltName for a certificate.  This is a serious limitation.  Per
   RFC 2818 [RFC2818] SAN is the object for providing email addresses
   and DNS addresses (FQDN), yet the common practice has been to use the
   commonName object within the distinguishedName object.  How much of
   this is due to the difficulty in creating certificates with a SAN?

   Thus the only way to provide a SAN is through the config file.  And
   there are two approaches.  This document uses an environment variable
   to provide the SAN value into the config file.  Another approach is
   to use piping as in:


   openssl req -new -sha256 -key domain.key\
    -subj "/C=US/ST=CA/O=Acme, Inc./CN=foo.com" -reqexts SAN\
     -config <(cat /etc/ssl/openssl.cnf\
      <(printf "[SAN]\nsubjectAltName=DNS:foo.com,DNS:www.foo.com"))\
     -out domain.csr


9.4.  DER support, or lack thereof

   The long, hard-fought battle with openssl to create a full DER pki
   failed.  The is no facility to create a DER certificate from a DER
   CSR.  It just is not there in the 'openssl ca' command.  Even the
   'openssl x509 -req' command cannot do this for a simple certificate.

   Further, there is no 'hack' for making a certificate chain as there
   is with PEM.  With PEM a simple concatenation of the certificates
   create a usable certificate chain.  For DER, some recommend using
   PKCS#7 [RFC2315], where others point out that this format is poorly
   support 'in the field', whereas PKCS#12 [RFC7292] works for them.

   Finally, openssl does supports converting a PEM certificate to DER:


   openssl x509 -outform der -in certificate.pem -out certificate.der


   This should also work for the keypair.  However, in a highly
   constrained device it may make more sense to just store the raw
   keypair in the device's very limited secure storage.




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10.  IANA Considerations

   TBD.  May be nothing for IANA.

11.  Security Considerations

11.1.  Adequate Randomness

   Creating certificates takes a lot of random numbers.  A good source
   of random numbers is critical.  Studies [WeakKeys] have found
   excessive amount of certificates, all with the same keys due to bad
   randomness on the generating systems.  The amount of entropy
   available for these random numbers can be tested.  On Fedora/Centos
   use:

   cat /proc/sys/kernel/random/entropy_avail

   If the value is low (below 1000) check your system's randomness
   source.  Is rng-tools installed?  Consider adding an entropy
   collection service like haveged from issihosts.com/haveged.

11.2.  Key pair Theft

   During the certificate creation, particularly during keypair
   generation, the files are vulnerable to theft.  This can be mitigate
   using umask.  Before using openssl, set umask:

   restore_mask=$(umask -p)
   umask 077

   Afterwards, restore it with:

   $restore_mask

12.  Acknowledgments

   This work was jump started by the excellent RSA pki guide by Jamie
   Nguyen.  The openssl-user mailing list, with its many supportive
   experts; in particular: Rich Salz, Jakob Bolm, Viktor Dukhovni, and
   Erwann Abalea, was of immense help as was the openssl man pages
   website.

   Finally, "Professor Google" was always ready to point to answers to
   questions like: "openssl subjectAltName on the command line".  And
   the Professor, it seems, never tires of answering even trivial
   questions.





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13.  References

13.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
              editor.org/info/rfc2119>.

13.2.  Informative References

   [IEEE.802.1AR_2009]
              IEEE, "IEEE Standard for Local and metropolitan area
              networks - Secure Device Identity", IEEE 802.1AR-2009,
              DOI 10.1109/ieeestd.2009.5367679, December 2009,
              <http://ieeexplore.ieee.org/servlet/
              opac?punumber=5367676>.

   [RFC2315]  Kaliski, B., "PKCS #7: Cryptographic Message Syntax
              Version 1.5", RFC 2315, DOI 10.17487/RFC2315, March 1998,
              <https://www.rfc-editor.org/info/rfc2315>.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
              DOI 10.17487/RFC2818, May 2000, <https://www.rfc-
              editor.org/info/rfc2818>.

   [RFC7292]  Moriarty, K., Ed., Nystrom, M., Parkinson, S., Rusch, A.,
              and M. Scott, "PKCS #12: Personal Information Exchange
              Syntax v1.1", RFC 7292, DOI 10.17487/RFC7292, July 2014,
              <https://www.rfc-editor.org/info/rfc7292>.

   [WeakKeys]
              Heninger, N., Durumeric, Z., Wustrow, E., and J.
              Halderman, "Detection of Widespread Weak Keys in Network
              Devices", July 2011,
              <https://www.usenix.org/system/files/conference/
              usenixsecurity12/sec12-final228.pdf>.

Appendix A.  OpenSSL config files

A.1.  OpenSSL Root config file

   The following is the openssl-root.cnf file contents


   # OpenSSL root CA configuration file.
   # Copy to `$dir/openssl.cnf`.




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   [ ca ]
   # `man ca`
   default_ca = CA_default

   [ CA_default ]
   # Directory and file locations.
   dir               = $ENV::dir
   cadir             = $ENV::cadir
   format            = $ENV::format

   certs             = $dir/certs
   crl_dir           = $dir/crl
   new_certs_dir     = $dir/newcerts
   database          = $dir/index.txt
   serial            = $dir/serial
   RANDFILE          = $dir/private/.rand

   # The root key and root certificate.
   private_key       = $cadir/private/ca.key.$format
   certificate       = $cadir/certs/ca.cert.$format

   # For certificate revocation lists.
   crlnumber         = $dir/crlnumber
   crl               = $dir/crl/ca.crl.pem
   crl_extensions    = crl_ext
   default_crl_days  = 30

   # SHA-1 is deprecated, so use SHA-2 instead.
   default_md        = sha256

   name_opt          = ca_default
   cert_opt          = ca_default
   default_days      = 375
   preserve          = no
   policy            = policy_strict
   copy_extensions   = copy

   [ policy_strict ]
   # The root CA should only sign intermediate certificates that match.
   # See the POLICY FORMAT section of `man ca`.
   countryName             = match
   stateOrProvinceName     = match
   organizationName        = match
   organizationalUnitName  = optional
   commonName              = optional

   [ policy_loose ]
   # Allow the intermediate CA to sign a more



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   #   diverse range of certificates.
   # See the POLICY FORMAT section of the `ca` man page.
   countryName             = optional
   stateOrProvinceName     = optional
   localityName            = optional
   organizationName        = optional
   organizationalUnitName  = optional
   commonName              = optional

   [ req ]
   # Options for the `req` tool (`man req`).
   default_bits        = 2048
   distinguished_name  = req_distinguished_name
   string_mask         = utf8only
   req_extensions      = req_ext

   # SHA-1 is deprecated, so use SHA-2 instead.
   default_md          = sha256

   # Extension to add when the -x509 option is used.
   x509_extensions     = v3_ca

   [ req_distinguished_name ]
   # See <https://en.wikipedia.org/wiki/Certificate_signing_request>.
   countryName                     = Country Name (2 letter code)
   stateOrProvinceName             = State or Province Name
   localityName                    = Locality Name
   0.organizationName              = Organization Name
   organizationalUnitName          = Organizational Unit Name
   commonName                      = Common Name

   # Optionally, specify some defaults.
   # countryName_default             = US
   # stateOrProvinceName_default     = MI
   # localityName_default            = Oak Park
   # 0.organizationName_default      = HTT Consulting
   # organizationalUnitName_default  =

   [ req_ext ]
   subjectAltName = $ENV::subjectAltName

   [ v3_ca ]
   # Extensions for a typical CA (`man x509v3_config`).
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid:always,issuer
   basicConstraints = critical, CA:true
   # keyUsage = critical, digitalSignature, cRLSign, keyCertSign
   keyUsage = critical, cRLSign, keyCertSign



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   subjectAltName = $ENV::subjectAltName

   [ v3_intermediate_ca ]
   # Extensions for a typical intermediate CA (`man x509v3_config`).
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid:always,issuer
   basicConstraints = critical, CA:true, pathlen:0
   # keyUsage = critical, digitalSignature, cRLSign, keyCertSign
   keyUsage = critical, cRLSign, keyCertSign

   [ crl_ext ]
   # Extension for CRLs (`man x509v3_config`).
   authorityKeyIdentifier=keyid:always

   [ ocsp ]
   # Extension for OCSP signing certificates (`man ocsp`).
   basicConstraints = CA:FALSE
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid,issuer
   keyUsage = critical, digitalSignature
   extendedKeyUsage = critical, OCSPSigning


A.2.  OpenSSL Intermediate config file

   The following is the openssl-intermediate.cnf file contents.

   Remove the crlDistributionPoints to drop CRL support and
   authorityInfoAccess to drop OCSP support.


   # OpenSSL intermediate CA configuration file.
   # Copy to `$dir/intermediate/openssl.cnf`.

   [ ca ]
   # `man ca`
   default_ca = CA_default

   [ CA_default ]
   # Directory and file locations.
   dir               = $ENV::dir
   cadir             = $ENV::cadir
   format            = $ENV::format

   certs             = $dir/certs
   crl_dir           = $dir/crl
   new_certs_dir     = $dir/newcerts
   database          = $dir/index.txt



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   serial            = $dir/serial
   RANDFILE          = $dir/private/.rand

   # The Intermediate key and Intermediate certificate.
   private_key       = $dir/private/intermediate.key.$format
   certificate       = $dir/certs/intermediate.cert.$format

   # For certificate revocation lists.
   crlnumber         = $dir/crlnumber
   crl               = $dir/crl/intermediate.crl.pem
   crl_extensions    = crl_ext
   default_crl_days  = $ENV::default_crl_days

   # SHA-1 is deprecated, so use SHA-2 instead.
   default_md        = sha256

   name_opt          = ca_default
   cert_opt          = ca_default
   default_days      = 375
   preserve          = no
   policy            = policy_loose
   copy_extensions   = copy

   [ policy_strict ]
   # The root CA should only sign intermediate certificates that match.
   # See the POLICY FORMAT section of `man ca`.
   countryName             = match
   stateOrProvinceName     = match
   organizationName        = match
   organizationalUnitName  = optional
   commonName              = optional

   [ policy_loose ]
   # Allow the intermediate CA to sign a more
   #  diverse range of certificates.
   # See the POLICY FORMAT section of the `ca` man page.
   countryName             = optional
   stateOrProvinceName     = optional
   localityName            = optional
   organizationName        = optional
   organizationalUnitName  = optional
   commonName              = optional
   UID                     = optional

   [ req ]
   # Options for the `req` tool (`man req`).
   default_bits        = 2048
   distinguished_name  = req_distinguished_name



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   string_mask         = utf8only
   req_extensions      = req_ext

   # SHA-1 is deprecated, so use SHA-2 instead.
   default_md          = sha256

   # Extension to add when the -x509 option is used.
   x509_extensions     = v3_ca

   [ req_distinguished_name ]
   # See <https://en.wikipedia.org/wiki/Certificate_signing_request>.
   countryName                     = Country Name (2 letter code)
   stateOrProvinceName             = State or Province Name
   localityName                    = Locality Name
   0.organizationName              = Organization Name
   organizationalUnitName          = Organizational Unit Name
   commonName                      = Common Name
   UID                             = User ID

   # Optionally, specify some defaults.
   # countryName_default             = US
   # stateOrProvinceName_default     = MI
   # localityName_default            = Oak Park
   # 0.organizationName_default      = HTT Consulting
   # organizationalUnitName_default  =

   [ req_ext ]
   subjectAltName = $ENV::subjectAltName

   [ v3_ca ]
   # Extensions for a typical CA (`man x509v3_config`).
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid:always,issuer
   basicConstraints = critical, CA:true
   # keyUsage = critical, digitalSignature, cRLSign, keyCertSign
   keyUsage = critical, cRLSign, keyCertSign

   [ v3_intermediate_ca ]
   # Extensions for a typical intermediate CA (`man x509v3_config`).
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid:always,issuer
   basicConstraints = critical, CA:true, pathlen:0
   # keyUsage = critical, digitalSignature, cRLSign, keyCertSign
   keyUsage = critical, cRLSign, keyCertSign

   [ usr_cert ]
   # Extensions for client certificates (`man x509v3_config`).
   basicConstraints = CA:FALSE



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   nsCertType = client, email
   nsComment = "OpenSSL Generated Client Certificate"
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid,issuer
   keyUsage = critical,nonRepudiation,digitalSignature,keyEncipherment
   extendedKeyUsage = clientAuth, emailProtection
   crlDistributionPoints = $ENV::crlDP
   authorityInfoAccess = $ENV::ocspIAI

   [ server_cert ]
   # Extensions for server certificates (`man x509v3_config`).
   basicConstraints = CA:FALSE
   nsCertType = server
   nsComment = "OpenSSL Generated Server Certificate"
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid,issuer:always
   keyUsage = critical, digitalSignature, keyEncipherment
   extendedKeyUsage = serverAuth
   crlDistributionPoints = $ENV::crlDP
   authorityInfoAccess = $ENV::ocspIAI

   [ crl_ext ]
   # Extension for CRLs (`man x509v3_config`).
   authorityKeyIdentifier=keyid:always

   [ ocsp ]
   # Extension for OCSP signing certificates (`man ocsp`).
   basicConstraints = CA:FALSE
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid,issuer
   keyUsage = critical, digitalSignature
   extendedKeyUsage = critical, OCSPSigning


A.3.  OpenSSL 802.1AR Intermediate config file

   The following is the openssl-8021ARintermediate.cnf file contents.

   Remove the crlDistributionPoints to drop CRL support and
   authorityInfoAccess to drop OCSP support.


   # OpenSSL 8021ARintermediate CA configuration file.
   # Copy to `$dir/8021ARintermediate/openssl_8021ARintermediate.cnf`.

   [ ca ]
   # `man ca`
   default_ca = CA_default



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   [ CA_default ]
   # Directory and file locations.
   # dir               = /root/ca/8021ARintermediate
   dir               = $ENV::dir
   cadir             = $ENV::cadir
   format            = $ENV::format

   certs             = $dir/certs
   crl_dir           = $dir/crl
   new_certs_dir     = $dir/newcerts
   database          = $dir/index.txt
   serial            = $dir/serial
   RANDFILE          = $dir/private/.rand

   # The root key and root certificate.
   private_key       = $dir/private/8021ARintermediate.key.$format
   certificate       = $dir/certs/8021ARintermediate.cert.$format

   # For certificate revocation lists.
   crlnumber         = $dir/crlnumber
   crl               = $dir/crl/ca.crl.pem
   crl_extensions    = crl_ext
   default_crl_days  = $ENV::default_crl_days

   # SHA-1 is deprecated, so use SHA-2 instead.
   default_md        = sha256

   name_opt          = ca_default
   cert_opt          = ca_default
   default_enddate   = 99991231235959Z # per IEEE 802.1AR
   preserve          = no
   policy            = policy_loose
   copy_extensions   = copy

   [ policy_strict ]
   # The root CA should only sign 8021ARintermediate
   #   certificates that match.
   # See the POLICY FORMAT section of `man ca`.
   countryName             = match
   stateOrProvinceName     = match
   organizationName        = match
   organizationalUnitName  = optional
   commonName              = optional

   [ policy_loose ]
   # Allow the 8021ARintermediate CA to sign
   #   a more diverse range of certificates.
   # See the POLICY FORMAT section of the `ca` man page.



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   countryName             = optional
   stateOrProvinceName     = optional
   localityName            = optional
   organizationName        = optional
   organizationalUnitName  = optional
   commonName              = optional
   serialNumber            = optional

   [ req ]
   # Options for the `req` tool (`man req`).
   default_bits        = 2048
   distinguished_name  = req_distinguished_name
   string_mask         = utf8only
   req_extensions      = req_ext

   # SHA-1 is deprecated, so use SHA-2 instead.
   default_md          = sha256

   # Extension to add when the -x509 option is used.
   x509_extensions     = v3_ca

   [ req_distinguished_name ]
   # See <https://en.wikipedia.org/wiki/Certificate_signing_request>.
   countryName                     = Country Name (2 letter code)
   stateOrProvinceName             = State or Province Name
   localityName                    = Locality Name
   0.organizationName              = Organization Name
   organizationalUnitName          = Organizational Unit Name
   commonName                      = Common Name
   serialNumber                    = Device Serial Number

   # Optionally, specify some defaults.
   0.organizationName_default      = HTT Consulting
   organizationalUnitName_default  = Devices

   [ req_ext ]
   subjectAltName = $ENV::subjectAltName

   [ hmodname ]
   hwType = OID:$ENV::hwType
   hwSerialNum = FORMAT:HEX,OCT:$ENV::hwSerialNum

   [ v3_ca ]
   # Extensions for a typical CA (`man x509v3_config`).
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid:always,issuer
   basicConstraints = critical, CA:true
   keyUsage = critical, digitalSignature, cRLSign, keyCertSign



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   [ v3_8021ARintermediate_ca ]
   # Extensions for a typical
   #   8021ARintermediate CA (`man x509v3_config`).
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid:always,issuer
   basicConstraints = critical, CA:true, pathlen:0
   # keyUsage = critical, digitalSignature, cRLSign, keyCertSign
   keyUsage = critical, cRLSign, keyCertSign

   [ 8021ar_idevid ]
   # Extensions for IEEE 802.1AR iDevID
   #   certificates (`man x509v3_config`).
   basicConstraints = CA:FALSE
   authorityKeyIdentifier = keyid,issuer:always
   keyUsage = critical, digitalSignature, keyEncipherment
   crlDistributionPoints = $ENV::crlDP
   authorityInfoAccess = $ENV::ocspIAI

   [ crl_ext ]
   # Extension for CRLs (`man x509v3_config`).
   authorityKeyIdentifier=keyid:always

   [ ocsp ]
   # Extension for OCSP signing certificates (`man ocsp`).
   basicConstraints = CA:FALSE
   subjectKeyIdentifier = hash
   authorityKeyIdentifier = keyid,issuer
   keyUsage = critical, digitalSignature
   extendedKeyUsage = critical, OCSPSigning


Authors' Addresses

   Robert Moskowitz
   Huawei
   Oak Park, MI  48237

   Email: rgm@labs.htt-consult.com


   Henk Birkholz
   Fraunhofer SIT
   Rheinstrasse 75
   Darmstadt  64295
   Germany

   Email: henk.birkholz@sit.fraunhofer.de




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   Liang Xia
   Huawei
   No. 101, Software Avenue, Yuhuatai District
   Nanjing
   China

   Email: Frank.xialiang@huawei.com












































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