CSR erstellen

Submitted by admin on So, 11.12.2016 - 11:19

1438416147892-x509.certificate.icon.png

Für ein X.509 Zertifikat wird - wenn man es richtig macht - ein Certificate Signing Request (CSR) benötigt. Das Skript in diesem Beitrag erzeugt einen CSR, der von den meisten PKIs akzeptiert werden sollte.

Das Sktipt erzeugt ein temporäres openssl Config File, so dass auch mehrere CNs (Hostnamen) angegeben werden können, was z.B. für CAcert notwendig ist, will man ein Zertifikat erstellen, das für mehrere Hostnamen gültig ist.

#!/bin/bash

usage() {
  echo "usage: $0 <hostname> [<more hostnames>...]"
  exit 1
}

SUBJ_PREFIX="/C=DE/ST=Hessen/L=Taunusstein/O=Christian Felsing"        
# comment EC_ALGO if you want RSA
#EC_ALGO="secp521r1"
#EC_ALGO="prime256v1"

HOSTNAME=$1

if [ -z "$HOSTNAME" ]; then
  usage
fi

OPENSSLCNF="/tmp/openssl.$$.cf"

declare -a ARGV
ARGV=("$@")

cat > "$OPENSSLCNF" <<EOF
#
# 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/pki/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 ctificates with same subject.
new_certs_dir	= \$dir/newcerts		# default place for new certs.

certificate	= \$dir/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.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 extentions 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	= 365			# how long to certify for
default_crl_days= 30			# how long before next CRL
default_md	= sha256		# use SHA-256 by default
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_md		= sha256
default_keyfile 	= privkey.pem
distinguished_name	= req_distinguished_name
attributes		= req_attributes
x509_extensions	= v3_ca	# The extentions 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		= XX
countryName_min			= 2
countryName_max			= 2

stateOrProvinceName		= State or Province Name (full name)
#stateOrProvinceName_default	= Default Province

localityName			= Locality Name (eg, city)
localityName_default		= Default City

0.organizationName		= Organization Name (eg, company)
0.organizationName_default	= Default Company Ltd

# 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	=

commonName			= Common Name (eg, your name or your server\'s hostname)
commonName_max			= 64

emailAddress			= Email Address
emailAddress_max		= 64

# 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

[ v3_req ]

# Extensions to add to a certificate request
subjectAltName = @alt_names

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

[alt_names]
DNS.1 = $HOSTNAME
EOF

ARGC=$#
for (( i=0; i<$ARGC; i++ )); do
  ALTNAME=${ARGV[${i}]}
  echo "DNS.${i} = ${ALTNAME}" >> "$OPENSSLCNF"
done

cat >> "$OPENSSLCNF" <<EOF

[ v3_ca ]

subjectAltName = @alt_names

# Extensions for a typical CA


# PKIX recommendation.

subjectKeyIdentifier=hash

authorityKeyIdentifier=keyid:always,issuer

# This is what PKIX recommends but some broken software chokes on critical
# extensions.
#basicConstraints = critical,CA:true
# So we do this instead.
basicConstraints = CA:true

# 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

# 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)

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)
EOF

DAYS=3650

umask 077
REQFILE=${HOSTNAME}.csr

if [ -z "$EC_ALGO" ]; then
  openssl req -config "$OPENSSLCNF" -nodes -newkey rsa:4096 -sha256 -subj "${SUBJ_PREFIX}/CN=${HOSTNAME}" -keyout ${HOSTNAME}.key -out ${REQFILE} -days $DAYS
else
  openssl ecparam -out "${HOSTNAME}.key" -name ${EC_ALGO} -genkey
  openssl req -new -config "$OPENSSLCNF" -nodes -key "${HOSTNAME}.key" -sha256 -subj "${SUBJ_PREFIX}/CN=${HOSTNAME}" -out ${REQFILE} -days $DAYS
fi

chmod 644 "${REQFILE}"
umask 022

rm -f "$OPENSSLCNF"

Eine Besonderheit des Skripts besteht darin, dass man mit der Einstellung RSA=1 Zertifikate mit einem RSA Key erstellen kann, was alle PKI unterstützten. Wird RSA auf 0 gesetzt, dann wird ein Key auf Basis elliptischer Kurven erstellt. Das klappt jedoch nur mit einer aktuellen OpenSSL Version ab 1.0.1. Die meisten PKI unterstützen jedoch keine elliptischen Kurven.