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.
A file containing a single Netscape signed public key and challenge
and additional field values to be signed by the CA. See the SPKAC FORMAT
section for information on the required input and output format.
The output file to output certificates to. The default is standard
output. The certificate details will also be printed out to this
file in PEM format (except that -spkac outputs DER format).
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.
Indicates the issued certificates are to be signed with the key
the certificate requests were signed with (given with -keyfile).
Certificate requests signed with a different key are ignored. If
-spkac, -ss_cert or -gencrl are given, -selfsign is
ignored.
A consequence of using -selfsign is that the self-signed
certificate appears among the entries in the certificate database
(see the configuration option database), and uses the same
serial number counter as all other certificates sign with the
self-signed certificate.
This allows the start date to be explicitly set. The format of the
date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure), or
YYYYMMDDHHMMSSZ (the same as an ASN1 GeneralizedTime structure). In
both formats, seconds SS and timezone Z must be present.
This allows the expiry date to be explicitly set. The format of the
date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure), or
YYYYMMDDHHMMSSZ (the same as an ASN1 GeneralizedTime structure). In
both formats, seconds SS and timezone Z must be present.
The message digest to use.
Any digest supported by the OpenSSL dgst command can be used. For signing
algorithms that do not support a digest (i.e. Ed25519 and Ed448) any message
digest that is set is ignored. This option also applies to CRLs.
This option 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. Check out the POLICY FORMAT section
for more information.
This is a deprecated 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.
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.
The DN of a certificate can contain the EMAIL field if present in the
request DN, however, it is good policy just having the e-mail set into
the altName extension of the certificate. When this option is set the
EMAIL field is removed from the certificate' subject and set only in
the, eventually present, extensions. The email_in_dn keyword can be
used in the configuration file to enable this behaviour.
The section of the configuration file containing certificate extensions
to be added when a certificate is issued (defaults to x509_extensions
unless the -extfile option is used). 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. See the
x509v3_config(5) manual page for details of the
extension section format.
Specifying an engine (by its unique id string) will cause ca
to attempt to obtain a functional reference to the specified engine,
thus initialising it if needed. The engine will then be set as the default
for all available algorithms.
Supersedes subject name given in the request.
The arg must be formatted as /type0=value0/type1=value1/type2=....
Keyword characters may be escaped by \ (backslash), and whitespace is retained.
Empty values are permitted, but the corresponding type will not be included
in the resulting certificate.
This option causes field values to be interpreted as UTF8 strings, by
default they are interpreted as ASCII. This means that the field
values, whether prompted from a terminal or obtained from a
configuration file, must be valid UTF8 strings.
If reading serial from the text file as specified in the configuration
fails, specifying this option creates a new random serial to be used as next
serial number.
To get random serial numbers, use the -rand_serial flag instead; this
should only be used for simple error-recovery.
A file or files containing random data used to seed the random number
generator.
Multiple files can be specified separated by an OS-dependent character.
The separator is ; for MS-Windows, , for OpenVMS, and : for
all others.
Revocation reason, where reason is one of: unspecified, keyCompromise,
CACompromise, affiliationChanged, superseded, cessationOfOperation,
certificateHold or removeFromCRL. The matching of reason is case
insensitive. Setting any revocation reason will make the CRL v2.
In practice removeFromCRL is not particularly useful because it is only used
in delta CRLs which are not currently implemented.
This sets the CRL revocation reason code to certificateHold and the hold
instruction to instruction which must be an OID. Although any OID can be
used only holdInstructionNone (the use of which is discouraged by RFC2459)
holdInstructionCallIssuer or holdInstructionReject will normally be used.
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 (for example Netscape) can't handle V2 CRLs. See
x509v3_config(5) manual page for details of the
extension section format.
The section of the configuration file containing options for ca
is found as follows: 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:
RANDFILE
preserve
msie_hack
With the exception of RANDFILE, this is probably a bug and may
change in future releases.
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) used.
This 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.
This 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 -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.
If the value yes is given, the valid certificate entries in the
database must have unique subjects. if the value no is given,
several valid certificate entries may have the exact same subject.
The default value is yes, to be compatible with older (pre 0.9.8)
versions of OpenSSL. However, to make CA certificate roll-over easier,
it's recommended to use the value no, especially if combined with
the -selfsign command line option.
Note that it is valid in some circumstances for certificates to be created
without any subject. In the case where there are multiple certificates without
subjects this does not count as a duplicate.
A text file containing the next CRL number to use in hex. The crl number
will be inserted in the CRLs only if this file exists. If this file is
present, it must contain a valid CRL number.
The same as -noemailDN. If you want the EMAIL field to be removed
from the DN of the certificate simply set this to 'no'. If not present
the default is to allow for the EMAIL filed in the certificate's DN.
These options allow the format used to display the certificate details
when asking the user to confirm signing. All the options supported by
the x509 utilities -nameopt and -certopt switches can be used
here, except the no_signame and no_sigdump are permanently set
and cannot be disabled (this is because the certificate signature cannot
be displayed because the certificate has not been signed at this point).
For convenience the values ca_default are accepted by both to produce
a reasonable output.
If neither option is present the format used in earlier versions of
OpenSSL is used. Use of the old format is strongly discouraged because
it only displays fields mentioned in the policy section, mishandles
multicharacter string types and does not display extensions.
Determines how extensions in certificate requests should be handled.
If set to none or this option is not present then extensions are
ignored and not copied to the certificate. If set to copy then any
extensions present in the request that are not already present are copied
to the certificate. If set to copyall then all extensions in the
request are copied to the certificate: if the extension is already present
in the certificate it is deleted first. See the WARNINGS section before
using this option.
The main use of this option is to allow a certificate request to supply
values for certain extensions such as subjectAltName.
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 intended behaviour.
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 '.'.
When processing SPKAC format, the output is DER if the -out
flag is used, but PEM format if sending to stdout or the -outdir
flag is used.
Note: 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):
SPKAC=MIG0MGAwXDANBgkqhkiG9w0BAQEFAANLADBIAkEAn7PDhCeV/xIxUg8V70YRxK2A5
CN=Steve Test
emailAddress=steve@openssl.org
0.OU=OpenSSL Group
1.OU=Another Group
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
#rand_serial = yes # for random serial#'s
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
email_in_dn = no # Don't add the email into cert DN
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
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.
V2 CRL features like delta CRLs are not currently supported.
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.
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 script
CA.pl helps 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. To
enforce the absence of the EMAIL field within the DN, as suggested by
RFCs, regardless the contents of the request' subject the -noemailDN
option can be used. The behaviour should be more friendly and
configurable.
Canceling some commands by refusing to certify a certificate can
create an empty file.
The ca command is quirky and at times downright unfriendly.
The ca utility was originally meant as an example of how to do things
in a CA. It was not supposed to be used as a full blown CA itself:
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 copy_extensions option should be used with caution. If care is
not taken then it can be a security risk. For example if a certificate
request contains a basicConstraints extension with CA:TRUE and the
copy_extensions value is set to copyall and the user does not spot
this when the certificate is displayed then this will hand the requester
a valid CA certificate.
This situation can be avoided by setting copy_extensions to copy
and including basicConstraints with CA:FALSE in the configuration file.
Then if the request contains a basicConstraints extension it will be
ignored.
It is advisable to also include values for other extensions such
as keyUsage to prevent a request supplying its own values.
Additional restrictions can be placed on the CA certificate itself.
For example if the CA certificate has:
basicConstraints = CA:TRUE, pathlen:0
then even if a certificate is issued with CA:TRUE it will not be valid.
Since OpenSSL 1.1.1, the program follows RFC5280. Specifically,
certificate validity period (specified by any of -startdate,
-enddate and -days) will be encoded as UTCTime if the dates are
earlier than year 2049 (included), and as GeneralizedTime if the dates
are in year 2050 or later.
Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
https://www.openssl.org/source/license.html.