Création d'une CA

Afin de pouvoir administrer nos certificats, nous créons une CA. Dans l'immédiat, tout se fera en ligne de commande.

Nous créons le répertoire qui va accueillir le CA, et les répertoires qui le compose, et sécurisons le répertoire “private”

# sudo mkdir -p /etc/ssl/CA/{certs,crl,newcerts,private}
# chmod 700 /etc/ssl/CA/private
# cd /etc/ssl/CA

Nous créons le fichier d'index

# touch index.txt
# echo 1000 > serial

Nous copions le fichier openssl.cnf depuis /etc/ssl/ dans /etc/ssl/CA

# cp -v /etc/ssl/openssl.cnf /etc/ssl/CA/openssl.cnf

Nous adaptons le fichier openssl.cnf pour qu'il ressemble à cela

#
# OpenSSL example configuration file.
# This is mostly being used for generation of certificate requests.
#

# This definition stops the following lines choking if HOME isn't
# defined.
HOME			= .
RANDFILE		= $ENV::HOME/.rnd

# Extra OBJECT IDENTIFIER info:
#oid_file		= $ENV::HOME/.oid
oid_section		= new_oids

# To use this configuration file with the "-extfile" option of the
# "openssl x509" utility, name here the section containing the
# X.509v3 extensions to use:
# extensions		= 
# (Alternatively, use a configuration file that has only
# X.509v3 extensions in its main [= default] section.)

[ new_oids ]

# We can add new OIDs in here for use by 'ca', 'req' and 'ts'.
# Add a simple OID like this:
# testoid1=1.2.3.4
# Or use config file substitution like this:
# testoid2=${testoid1}.5.6

# Policies used by the TSA examples.
tsa_policy1 = 1.2.3.4.1
tsa_policy2 = 1.2.3.4.5.6
tsa_policy3 = 1.2.3.4.5.7

####################################################################
[ ca ]
default_ca	= CA_default		# The default ca section

####################################################################
[ CA_default ]

dir		= /etc/ssl/CA		# Where everything is kept
certs		= $dir/certs		# Where the issued certs are kept
crl_dir		= $dir/crl		# Where the issued crl are kept
database	= $dir/index.txt	# database index file.
#unique_subject	= no			# Set to 'no' to allow creation of
					# several certs with same subject.
new_certs_dir	= $dir/newcerts		# default place for new certs.

certificate	= $dir/certs/cacert.pem	# The CA certificate
serial		= $dir/serial		# The current serial number
crlnumber	= $dir/crlnumber	# the current crl number
					# must be commented out to leave a V1 CRL
crl		= $dir/crl/crl.pem		# The current CRL
private_key	= $dir/private/cakey.pem # The private key
RANDFILE	= $dir/private/.rand	# private random number file

x509_extensions	= usr_cert		# The extensions to add to the cert

# Comment out the following two lines for the "traditional"
# (and highly broken) format.
name_opt	= ca_default		# Subject Name options
cert_opt	= ca_default		# Certificate field options

# Extension copying option: use with caution.
# copy_extensions = copy

# Extensions to add to a CRL. Note: Netscape communicator chokes on V2 CRLs
# so this is commented out by default to leave a V1 CRL.
# crlnumber must also be commented out to leave a V1 CRL.
crl_extensions	= crl_ext

default_days	= 375			# how long to certify for
default_crl_days= 30			# how long before next CRL
default_md	= default		# use public key default MD
preserve	= no			# keep passed DN ordering

# A few difference way of specifying how similar the request should look
# For type CA, the listed attributes must be the same, and the optional
# and supplied fields are just that :-)
policy		= policy_match

# For the CA policy
[ policy_match ]
countryName		= match
stateOrProvinceName	= match
organizationName	= match
organizationalUnitName	= optional
commonName		= supplied
emailAddress		= optional

# For the 'anything' policy
# At this point in time, you must list all acceptable 'object'
# types.
[ policy_anything ]
countryName		= optional
stateOrProvinceName	= optional
localityName		= optional
organizationName	= optional
organizationalUnitName	= optional
commonName		= supplied
emailAddress		= optional

####################################################################
[ req ]
default_bits		= 2048
default_keyfile		= privkey.pem
distinguished_name	= req_distinguished_name
attributes		= req_attributes
x509_extensions	= v3_ca	# The extensions to add to the self signed cert

# Passwords for private keys if not present they will be prompted for
# input_password = secret
# output_password = secret

# This sets a mask for permitted string types. There are several options. 
# default: PrintableString, T61String, BMPString.
# pkix	 : PrintableString, BMPString (PKIX recommendation before 2004)
# utf8only: only UTF8Strings (PKIX recommendation after 2004).
# nombstr : PrintableString, T61String (no BMPStrings or UTF8Strings).
# MASK:XXXX a literal mask value.
# WARNING: ancient versions of Netscape crash on BMPStrings or UTF8Strings.
string_mask = utf8only

# req_extensions = v3_req # The extensions to add to a certificate request

[ req_distinguished_name ]
countryName			= Country Name (2 letter code)
countryName_default		= FR
countryName_min			= 2
countryName_max			= 2

stateOrProvinceName		= State or Province Name (full name)
stateOrProvinceName_default	= Var

localityName			= Locality Name (eg, city)
localityName_default		= Vinon

0.organizationName		= Organization Name (eg, company)
0.organizationName_default	= Grohub Certificate Authority

# we can do this but it is not needed normally :-)
#1.organizationName		= Second Organization Name (eg, company)
#1.organizationName_default	= World Wide Web Pty Ltd

organizationalUnitName		= Organizational Unit Name (eg, section)
organizationalUnitName_default	= Security Team

commonName			= Common Name (e.g. server FQDN or YOUR name)
commonName_max			= 64

emailAddress			= Email Address
emailAddress_max		= 64
emailAddress_default		= sec@grohub.org

# SET-ex3			= SET extension number 3

[ req_attributes ]
challengePassword		= A challenge password
challengePassword_min		= 4
challengePassword_max		= 20

unstructuredName		= An optional company name

[ usr_cert ]

# These extensions are added when 'ca' signs a request.

# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.

basicConstraints=CA:FALSE

# Here are some examples of the usage of nsCertType. If it is omitted
# the certificate can be used for anything *except* object signing.

# This is OK for an SSL server.
# nsCertType			= server

# For an object signing certificate this would be used.
# nsCertType = objsign

# For normal client use this is typical
nsCertType = client, email

# and for everything including object signing:
# nsCertType = client, email, objsign

# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment

# This will be displayed in Netscape's comment listbox.
nsComment			= "OpenSSL Generated Certificate"

# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer

# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy
# An alternative to produce certificates that aren't
# deprecated according to PKIX.
# subjectAltName=email:move

# Copy subject details
# issuerAltName=issuer:copy

#nsCaRevocationUrl		= http://www.domain.dom/ca-crl.pem
#nsBaseUrl
#nsRevocationUrl
#nsRenewalUrl
#nsCaPolicyUrl
#nsSslServerName

# This is required for TSA certificates.
# extendedKeyUsage = critical,timeStamping
extendedKeyUsage = clientAuth, emailProtection

[ v3_req ]

# Extensions to add to a certificate request

basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment

[ v3_ca ]


# Extensions for a typical CA


# PKIX recommendation.

subjectKeyIdentifier=hash

authorityKeyIdentifier=keyid:always,issuer

basicConstraints = critical,CA:true, pathlen:0

# Key usage: this is typical for a CA certificate. However since it will
# prevent it being used as an test self-signed certificate it is best
# left out by default.
# keyUsage = cRLSign, keyCertSign
keyUsage = critical, digitalSignature, cRLSign, keyCertSign

# Some might want this also
# nsCertType = sslCA, emailCA

# Include email address in subject alt name: another PKIX recommendation
# subjectAltName=email:copy
# Copy issuer details
# issuerAltName=issuer:copy

# DER hex encoding of an extension: beware experts only!
# obj=DER:02:03
# Where 'obj' is a standard or added object
# You can even override a supported extension:
# basicConstraints= critical, DER:30:03:01:01:FF

[ crl_ext ]

# CRL extensions.
# Only issuerAltName and authorityKeyIdentifier make any sense in a CRL.

# issuerAltName=issuer:copy
authorityKeyIdentifier=keyid:always

[ proxy_cert_ext ]
# These extensions should be added when creating a proxy certificate

# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.

basicConstraints=CA:FALSE

# Here are some examples of the usage of nsCertType. If it is omitted
# the certificate can be used for anything *except* object signing.

# This is OK for an SSL server.
# nsCertType			= server

# For an object signing certificate this would be used.
# nsCertType = objsign

# For normal client use this is typical
# nsCertType = client, email

# and for everything including object signing:
# nsCertType = client, email, objsign

# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment

# This will be displayed in Netscape's comment listbox.
nsComment			= "OpenSSL Generated Certificate"

# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer

# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy
# An alternative to produce certificates that aren't
# deprecated according to PKIX.
# subjectAltName=email:move

# Copy subject details
# issuerAltName=issuer:copy

#nsCaRevocationUrl		= http://www.domain.dom/ca-crl.pem
#nsBaseUrl
#nsRevocationUrl
#nsRenewalUrl
#nsCaPolicyUrl
#nsSslServerName

# This really needs to be in place for it to be a proxy certificate.
proxyCertInfo=critical,language:id-ppl-anyLanguage,pathlen:3,policy:foo

####################################################################
[ tsa ]

default_tsa = tsa_config1	# the default TSA section

[ tsa_config1 ]

# These are used by the TSA reply generation only.
dir		= ./demoCA		# TSA root directory
serial		= $dir/tsaserial	# The current serial number (mandatory)
crypto_device	= builtin		# OpenSSL engine to use for signing
signer_cert	= $dir/tsacert.pem	# The TSA signing certificate
					# (optional)
certs		= $dir/cacert.pem	# Certificate chain to include in reply
					# (optional)
signer_key	= $dir/private/tsakey.pem # The TSA private key (optional)
signer_digest  = sha256			# Signing digest to use. (Optional)
default_policy	= tsa_policy1		# Policy if request did not specify it
					# (optional)
other_policies	= tsa_policy2, tsa_policy3	# acceptable policies (optional)
digests     = sha1, sha256, sha384, sha512  # Acceptable message digests (mandatory)
accuracy	= secs:1, millisecs:500, microsecs:100	# (optional)
clock_precision_digits  = 0	# number of digits after dot. (optional)
ordering		= yes	# Is ordering defined for timestamps?
				# (optional, default: no)
tsa_name		= yes	# Must the TSA name be included in the reply?
				# (optional, default: no)
ess_cert_id_chain	= no	# Must the ESS cert id chain be included?
				# (optional, default: no)

[ 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

[ 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

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

Nous créons la clé root du CA

# openssl genrsa -aes256 -out private/cakey.pem 4096

Entrez deux fois la passphrase que vous avez défini

Enter pass phrase for private/cakey.pem:
Verifying - Enter pass phrase for private/cakey.pem:

Et nous sécurisons la clé

# chmod 400 private/cakey.pem

Nous créons le certificat

# openssl req -config openssl.cnf -key private/cakey.pem -new -x509 -days 7300 -sha256 -extensions v3_ca -out certs/cacert.pem

Vous devez saisir la passphrase de la clé précédemment définie

Enter pass phrase for private/cakey.pem:

Répondez ensuite aux questions, ou laissez le choix par défaut (information entre crochets)

You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [FR]:
State or Province Name (full name) [Var]:
Locality Name (eg, city) [Vinon]:
Organization Name (eg, company) [Grohub Certificate Authority]:
Organizational Unit Name (eg, section) [Security Team]:
Common Name (e.g. server FQDN or YOUR name) []:Grohub Root CA
Email Address [sec@grohub.org]:

Nous vérifions le certificat

# openssl x509 -noout -text -in certs/cacert.pem

Nous créons le répertoire qui va accueillir le certificat intermédiaire

# mkdir /etc/ssl/CA/intermediate

Nous nous plaçons dans le répertoire, et créons l'arborescence

# mkdir -p /etc/ssl/CA/intermediate/{certs,crl,csr,newcerts,private}
# chmod 700 /etc/ssl/CA/intermediate/private
# cd /etc/ssl/CA/intermediate
# touch index.txt
# echo 1000 > serial

Nous ajoutons un fichier pour garder une trace de la liste des révocation de certificats

# echo 1000 > /etc/ssl/CA/intermediate/crlnumber

Nous copions le fichier de configuration

# cp -v /etc/ssl/CA/openssl.cnf /etc/ssl/CA/intermediate/openssl.cnf

Nous changeons les éléments suivants

[ CA_default ]
dir             = /root/ca/intermediate
private_key     = $dir/private/intermediatekey.pem
certificate     = $dir/certs/intermediatecert.pem
crl             = $dir/crl/intermediatecrl.pem
policy          = policy_loose

cd /etc/ssl/CA
# openssl genrsa -aes256 -out intermediate/private/intermediatekey.pem 4096

Nous saisissons une passphrase

Enter pass phrase for intermediate/private/intermediatekey.pem:
Verifying - Enter pass phrase for intermediate/private/intermediatekey.pem:

Nous sécurisons la clé

chmod 400 intermediate/private/intermediatekey.pem

Nous créons le CSR

# cd /etc/ssl/CA
# openssl req -config intermediate/openssl.cnf -new -sha256 -key intermediate/private/intermediatekey.pem -out intermediate/csr/intermediatecsr.pem

Nous créons le certificat

# cd /etc/ssl/CA
# openssl ca -config openssl.cnf -extensions v3_intermediate_ca -days 3650 -notext -md sha256 -in intermediate/csr/intermediatecsr.pem -out intermediate/certs/intermediatecert.pem

Nous confirmons deux fois avec “y”

Sign the certificate? [y/n]:y
1 out of 1 certificate requests certified, commit? [y/n]y

Nous sécurisons le certificat

# chmod 444 intermediate/certs/intermediatecert.pem

Pour vérifier le certificat

# openssl x509 -noout -text -in intermediate/certs/intermediatecert.pem

Pour vérifier

# openssl verify -CAfile certs/cacert.pem intermediate/certs/intermediatecert.pem

Vous devriez avoir cette réponse

intermediate/certs/intermediatecert.pem: OK

# cat intermediate/certs/intermediatecert.pem certs/cacert.pem > intermediate/certs/ca-chaincert.pem

Nous sécurisons le fichier

# chmod 444 intermediate/certs/ca-chaincert.pem

• OpenSSL Certificate Authority