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ca - Sample minimal CA application
openssl ca [-verbose] [-config filename] [-name section] [-gencrl] [-revoke
file] [-crldays days] [-crlhours hours] [-crlexts section] [-startdate
date] [-enddate date] [-days arg] [-md arg] [-policy arg] [-keyfile arg]
[-key arg] [-passin arg] [-cert file] [-in file] [-out file] [-notext]
[-outdir dir] [-infiles] [-spkac file] [-ss_cert file] [-preserveDN]
[-batch] [-msie_hack] [-extensions section]
Specifies the configuration file to use.
Specifies the configuration file section to use. Overrides
default_ca in the ca section.
An input filename containing a single certificate request to be
signed by the CA.
A single self signed certificate to be signed by the CA.
A file containing a single Netscape signed public key and challenge
and additional field values to be signed by the CA. See the NOTES
section for information on the required format.
If present this should be the last option, all subsequent arguments
are assumed to the the names of files containing certificate
The output file to output certificates to. The default is standard
output. The certificate details will also be printed out to this
The directory to output certificates to. The certificate will be
written to a filename consisting of the serial number in hex with
-cert The CA certificate file.
The private key to sign requests with.
The password used to encrypt the private key. Since on some systems
the command line arguments are visible (e.g. UNIX with the ps
utility) this option should be used with caution.
The key password source. For more information about the format of
arg see the Pass Prhase Arguments section in openssl(1ssl).
Prints extra details about the operations being performed.
-notext Does not output the text form of a certificate to the output file.
Allows the start date to be explicitly set. The format of the date
is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure).
Allows the expiration date to be explicitly set. The format of the
date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure).
The number of days to certify the certificate for.
-md alg The message digest to use. Possible values include md5, sha1 and
mdc2. This option also applies to CRLs.
Defines the CA policy to use. This is a section in the
configuration file which decides which fields should be mandatory
or match the CA certificate. See the POLICY FORMAT section for
A legacy option to make ca work with very old versions of the IE
certificate enrollment control certenr3. It used UniversalStrings
for almost everything. Since the old control has various security
bugs its use is strongly discouraged. The newer control Xenroll
does not need this option.
Normally the DN order of a certificate is the same as the order of
the fields in the relevant policy section. When this option is set
the order is the same as the request. This is largely for
compatibility with the older IE enrollment control which would only
accept certificates if their DNs match the order of the request.
This is not needed for Xenroll.
-batch Sets the batch mode. In this mode no questions will be asked and
all certificates will be certified automatically.
The section of the configuration file containing certificate
extensions to be added when a certificate is issued. If no
extension section is present then a V1 certificate is created. If
the extension section is present (even if it is empty) then a V3
certificate is created.
-gencrl Generates a CRL based on information in the index file.
The number of days before the next CRL is due. That is the days
from now to place in the CRL next Update field.
The number of hours before the next CRL is due.
A filename containing a certificate to revoke.
The section of the configuration file containing CRL extensions to
include. If no CRL extension section is present then a V1 CRL is
created, if the CRL extension section is present (even if it is
empty) then a V2 CRL is created. The CRL extensions specified are
CRL extensions and not CRL entry extensions. It should be noted
that some software (such as Netscape) cannot handle V2 CRLs.
CONFIGURATION FILE OPTIONS
The section of the configuration file containing options for ca is found as
If the -name command line option is used, then it names the section to be
used. Otherwise, the section to be used must be named in the default_ca
option of the ca section of the configuration file (or in the default
section of the configuration file). Besides default_ca, the following
options are read directly from the ca section:
With the exception of RANDFILE, this is probably a bug and may change in
Many of the configuration file options are identical to command line
options. Where the option is present in the configuration file and the
command line, the command line value is used. Where an option is described
as mandatory, then it must be present in the configuration file or the
command line equivalent (if any) is used.
Specifies a file containing additional OBJECT IDENTIFIERS. Each
line of the file should consist of the numerical form of the object
identifier followed by white space then the short name followed by
white space and finally the long name.
Specifies a section in the configuration file containing extra
object identifiers. Each line should consist of the short name of
the object identifier followed by = and the numerical form. The
short and long names are the same when this option is used.
The same as the -outdir command line option. It specifies the
directory where new certificates will be placed. Mandatory.
The same as the -cert option. It gives the file containing the CA
The same as the -keyfile option. The file containing the CA private
A file used to read and write random number seed information, or an
EGD socket (see RAND_egd(3)).
The same as the -days option. The number of days to certify a
The same as the -startdate option. The start date to certify a
certificate for. If not set the current time is used.
The same as the -enddate option. Either this option or default_days
(or the command line equivalents) must be present.
The same as the -crlhours and the -crldays options. These will only
be used if neither command line option is present. At least one of
these must be present to generate a CRL.
The same as the -md option. The message digest to use. Mandatory.
The text database file to use. Mandatory. This file must be present
though initially it will be empty.
A text file containing the next serial number to use in hex.
Mandatory. This file must be present and contain a valid serial
The same as the -extensions option.
The same as the -crlexts option.
The same as the -preserveDN option.
The same as the -msie_hack option.
policy The same as the -policy option. Mandatory.
The policy section consists of a set of variables corresponding to
certificate DN fields. If the value is match then the field value must
match the same field in the CA certificate. If the value is supplied then
it must be present. If the value is optional then it may be present. Any
fields not mentioned in the policy section are silently deleted, unless the
-preserveDN option is set but this can be regarded more of a quirk than
The input to the -spkac command line option is a Netscape signed public key
and challenge. This will usually come from the KEYGEN tag in an HTML form
to create a new private key. It is however possible to create SPKACs using
the spkac utility.
The file should contain the variable SPKAC set to the value of the SPKAC
and also the required DN components as name value pairs. If you need to
include the same component twice then it can be preceded by a number and a
The ca command is a minimal CA application. It can be used to sign
certificate requests in a variety of forms and generate CRLs it also
maintains a text database of issued certificates and their status.
The options descriptions will be divided into each purpose.
The ca utility originally was meant as an example of how to do things in a
CA. It was not supposed be be used as a full blown CA; nevertheless, some
people are using it for this purpose.
The ca command is effectively a single user command. No locking is done on
the various files and attempts to run more than one ca command on the same
database can have unpredictable results.
The text database index file is a critical part of the process and if
corrupted it can be difficult to fix. It is theoretically possible to
rebuild the index file from all the issued certificates and a current CRL.
However, there is no option to do this.
CRL entry extensions cannot currently be created. Only CRL extensions can
V2 CRL features like delta CRL support and CRL numbers are not currently
Although several requests can be input and handled at once it is only
possible to include one SPKAC or self signed certificate.
The use of an in memory text database can cause problems when large numbers
of certificates are present because, as the name implies the database has
to be kept in memory.
Certificate request extensions are ignored. Some kind of policy should be
included to use certain static extensions and certain extensions from the
It is not possible to certify two certificates with the same DN. This is a
side effect of how the text database is indexed and it cannot easily be
fixed without introducing other problems. Some S/MIME clients can use two
certificates with the same DN for separate signing and encryption keys.
The ca command really needs rewriting or the required functionality exposed
at either a command or interface level so a more friendly utility (perl
script or GUI) can handle things properly. The scripts CA.sh and CA.pl help
a little but not very much.
Any fields in a request that are not present in a policy are silently
deleted. This does not happen if the -preserveDN option is used but the
extra fields are not displayed when the user is asked to certify a request.
The behaviour should be more friendly and configurable.
Cancelling some commands by refusing to certify a certificate can create an
These examples assume that the ca directory structure is already set up and
the relevant files already exist. This usually involves creating a CA
certificate and private key with req, a serial number file and an empty
index file and placing them in the relevant directories.
To use the sample configuration file below the directories demoCA,
demoCA/private and demoCA/newcerts would be created. The CA certificate
would be copied to demoCA/cacert.pem and its private key to
demoCA/private/cakey.pem. A file demoCA/serial would be created containing
for example "01" and the empty index file demoCA/index.txt.
Sign a certificate request:
openssl ca -in req.pem -out newcert.pem
Sign a certificate request, using CA extensions:
openssl ca -in req.pem -extensions v3_ca -out newcert.pem
Generate a CRL
openssl ca -gencrl -out crl.pem
Sign several requests:
openssl ca -infiles req1.pem req2.pem req3.pem
Certify a Netscape SPKAC:
openssl ca -spkac spkac.txt
A sample SPKAC file (the SPKAC line has been truncated for clarity):
A sample configuration file with the relevant sections for ca:
[ ca ]
default_ca = CA_default # The default ca section
[ CA_default ]
dir = ./demoCA # top dir
database = $dir/index.txt # index file.
new_certs_dir = $dir/newcerts # new certs dir
certificate = $dir/cacert.pem # The CA cert
serial = $dir/serial # serial no file
private_key = $dir/private/cakey.pem# CA private key
RANDFILE = $dir/private/.rand # random number file
default_days = 365 # how long to certify for
default_crl_days= 30 # how long before next CRL
default_md = md5 # md to use
policy = policy_any # default policy
[ policy_any ]
countryName = supplied
stateOrProvinceName = optional
organizationName = optional
organizationalUnitName = optional
commonName = supplied
emailAddress = optional
OPENSSL_CONF reflects the location of master configuration file it can be
overridden by the -config command line option.
Note: the location of all files can change either by compile time options,
configuration file entries, environment variables or command line options.
The values below reflect the default values.
/usr/local/ssl/lib/openssl.cnf - master configuration file
./demoCA - main CA directory
./demoCA/cacert.pem - CA certificate
./demoCA/private/cakey.pem - CA private key
./demoCA/serial - CA serial number file
./demoCA/serial.old - CA serial number backup file
./demoCA/index.txt - CA text database file
./demoCA/index.txt.old - CA text database backup file
./demoCA/certs - certificate output file
./demoCA/.rnd - CA random seed information
Commands: req(1ssl), spkac(1ssl), x509(1ssl), CA.pl(1ssl)
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