CA upgrade in several aspects

egoitz--- via openssl-users <openssl-users@xxxxxxxxxxx> · Thu, 12 May 2022 17:38:19 +0200

Good afternoon,

I'm running a CA, for generating the certificates for the backup clients of my network and for the backup servers too. The certificates are used for encrypting the backups stored in the servers and too, for comunicating over TLS between severs and clients.

This CA has some years now and the certificates I generate for new clients, are not working (directly) in new machines. The reason for that is that new operating systems, are requiring stronger signing algorithms. When you try to start the service using that certificates (bacula file daemon) in a fresh new Debian for instance, systemd throws the following error : 

openssl.c:68 Error loading certificate file: ERR=error:140AB18E:SSL routines:SSL_CTX_use_certificate:ca md too weak

I know you can fix that with the following change in openssl.conf : 

####CipherString = DEFAULT@SECLEVEL=2
CipherString = DEFAULT@SECLEVEL=1

But this last way, does not convince me... so I have started debugging what exactly was causing the the problem. I saw, that sha1 is not allowed as a signing valid algorithm for SECLEVEL 2. So, I tried moving the CA to a more recent testing machine (with a newer OpenSSL 1.1.1l-freebsd), and I modified too in the openssl.conf of the CA (The openssl.conf existing in the CA dir for generating certs and so...) :
I have attached the old version. The new using version in the testing machine, is the old one plus the below changes :
- Added the line : "signer_digest  = sha256"
- Modified the line : "digests        = md5, sha1" by "digests         = sha1, sha256, sha384, sha512"
- Added the line : "ess_cert_id_alg        = sha1"

Now... I have generated a new certificate by following the normal procedure... generate the key and csr... later sing new cert... etc etc.....

This new generated certificate (signed with sha256WithRSAEncryption algorithm), has worked with a newer version of the Bacula client and in a almost new Debian system. So it seems, just by generating new certificates, using them in that new machines, with a newer os and keeping the old ca certificate, at least the service has started. We have too, another master public key for encrypting content (which is an oldly generated certificate signed with sha1WithRSAEncryption) that we keep in case a customer looses it's keys for avoiding a possible disaster.

I was wondering if some sort of problem could exist, by using those old two certificates (the master public key and the old ca certifcate) with the new generated certificate.

Now, that I have that CA, for whose purpose seems to be working, I have started thinking... some more... I have noticed that the CA certificate will expire in 2024. I assume that what I would have to do before that CA cert expires could be :

- Generate a second ca cert for the CA.
- Change the ca certificate to be used (for signing and issuing new certs) in openssl.conf :
certificate    = $dir/cacert-new.pem     # The CA certificate
- Sign again all the certificates in the CA...
- Change, all certificates in the CA (except the own ca cert which is already changed).
- Finally replace in each servers and clients certs.

Is this a correct procedure for upgrading a CA?. I assume it can be correct. Isn't it?. I think this procedure shouldn't break nothing related to serials of certificates and so in the own ca. Am I wrong?.

Best regards,

+are causing to set a special config in /etc/ssl/openssl.conf saying : "

# $FreeBSD: release/10.0.0/crypto/openssl/apps/openssl.cnf 238405 2012-07-12 19:30:53Z jkim $
#
# 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	= SARENET-CLOUDBACKUP-CA		# The default ca section

####################################################################
[ SARENET-CLOUDBACKUP-CA ]

dir		= /expert/SARENET-CLOUDBACKUP-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	= 3650			# 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 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		= ES
countryName_min			= 2
countryName_max			= 2

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

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

0.organizationName		= Organization Name (eg, company)
0.organizationName_default	= SARENET S.A.

# 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	= DEPARTAMENTO DE BACKUP

commonName			= Common Name (e.g. server FQDN or YOUR name)
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 SARENET CLOUDBACKUP 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

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

[ v3_ca ]

# 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