Manual: openssl-ca
OPENSSL-CA(1SSL) OpenSSL OPENSSL-CA(1SSL)
NAME
openssl-ca - sample minimal CA application
SYNOPSIS
openssl ca [-help] [-verbose] [-quiet] [-config filename] [-name section] [-section section]
[-gencrl] [-revoke file] [-valid file] [-status serial] [-updatedb] [-crl_reason reason] [-crl_hold
instruction] [-crl_compromise time] [-crl_CA_compromise time] [-crl_lastupdate date] [-crl_nextupdate
date] [-crldays days] [-crlhours hours] [-crlsec seconds] [-crlexts section] [-startdate date]
[-not_before date] [-enddate date] [-not_after date] [-days arg] [-md arg] [-policy arg] [-keyfile
filename|uri] [-keyform DER|PEM|P12|ENGINE] [-key arg] [-passin arg] [-cert file] [-certform
DER|PEM|P12] [-selfsign] [-in file] [-inform DER|] [-out file] [-notext] [-dateopt] [-outdir
dir] [-infiles] [-spkac file] [-ss_cert file] [-preserveDN] [-noemailDN] [-batch] [-msie_hack]
[-extensions section] [-extfile section] [-subj arg] [-utf8] [-sigopt nm:v] [-vfyopt nm:v]
[-create_serial] [-rand_serial] [-multivalue-rdn] [-rand files] [-writerand file] [-engine id]
[-provider name] [-provider-path path] [-provparam [name:]key=value] [-propquery propq] [certreq...]
DESCRIPTION
This command emulates a CA application. See the WARNINGS especially when considering to use it
productively.
It generates certificates bearing X.509 version 3. Unless specified otherwise, key identifier
extensions are included as described in x509v3_config(5).
It can be used to sign certificate requests (CSRs) in a variety of forms and generate certificate
revocation lists (CRLs). It also maintains a text database of issued certificates and their status.
When signing certificates, a single request can be specified with the -in option, or multiple
requests can be processed by specifying a set of certreq files after all options.
Note that there are also very lean ways of generating certificates: the req and x509 commands can be
used for directly creating certificates. See openssl-req(1) and openssl-x509(1) for details.
The descriptions of the ca command options are divided into each purpose.
OPTIONS
-help
Print out a usage message.
-verbose
This prints extra details about the operations being performed.
-quiet
This prints fewer details about the operations being performed, which may be handy during batch
scripts or pipelines.
-config filename
Specifies the configuration file to use. Optional; for a description of the default value, see
"COMMAND SUMMARY" in openssl(1).
-name section, -section section
Specifies the configuration file section to use (overrides default_ca in the ca section).
-in filename
An input filename containing a single certificate request (CSR) to be signed by the CA.
-inform DER|PEM
The format to use when loading certificate request (CSR) input files; by default PEM is tried
first. See openssl-format-options(1) for details.
-ss_cert filename
A single self-signed certificate to be signed by the CA.
-spkac filename
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.
-infiles
If present this should be the last option, all subsequent arguments are taken as the names of
files containing certificate requests.
-out filename
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).
-outdir directory
The directory to output certificates to. The certificate will be written to a filename consisting
of the serial number in hex with .pem appended.
-cert filename
The CA certificate, which must match with -keyfile.
-certform DER|PEM|P12
The format of the data in certificate input files; unspecified by default. See
openssl-format-options(1) for details.
-keyfile filename|uri
The CA private key to sign certificate requests with. This must match with -cert.
-keyform DER|PEM|P12|ENGINE
The format of the private key input file; unspecified by default. See openssl-format-options(1)
for details.
-sigopt nm:v
Pass options to the signature algorithm during sign operations. Names and values of these
options are algorithm-specific and documented in "Signature parameters" in provider-signature(7).
-vfyopt nm:v
Pass options to the signature algorithm during verify operations. Names and values of these
options are algorithm-specific.
This often needs to be given while signing too, because the self-signature of a certificate
signing request (CSR) is verified against the included public key, and that verification may need
its own set of options.
-key password
The password used to encrypt the private key. Since on some systems the command line arguments
are visible (e.g., when using ps(1) on Unix), this option should be used with caution. Better
use -passin.
-passin arg
The key password source for key files and certificate PKCS#12 files. For more information about
the format of arg see openssl-passphrase-options(1).
-selfsign
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.
-notext
Don't output the text form of a certificate to the output file.
-dateopt
Specify the date output format. Values are: rfc_822 and iso_8601. Defaults to rfc_822.
-startdate date, -not_before date
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. Alternatively, you can
also use "today".
-enddate date, -not_after date
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. Alternatively, you can
also use "today".
This overrides the -days option.
-days arg
The number of days from today to certify the certificate for.
Regardless of the option -not_before, the days are always counted from today. When used together
with the option -not_after/-startdate, the explicit expiry date takes precedence.
-md alg
The message digest to use. Any digest supported by the openssl-dgst(1) 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.
-policy arg
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.
-msie_hack
This is a deprecated option to make this command 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.
-preserveDN
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.
-noemailDN
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.
-batch
This sets the batch mode. In this mode no questions will be asked and all certificates will be
certified automatically.
-extensions section
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).
See the x509v3_config(5) manual page for details of the extension section format.
-extfile file
An additional configuration file to read certificate extensions from (using the default section
unless the -extensions option is also used).
-subj arg
Supersedes subject name given in the request.
The arg must be formatted as "/type0=value0/type1=value1/type2=...". Special characters may be
escaped by "\" (backslash), whitespace is retained. Empty values are permitted, but the
corresponding type will not be included in the resulting certificate. Giving a single "/" will
lead to an empty sequence of RDNs (a NULL-DN). Multi-valued RDNs can be formed by placing a "+"
character instead of a "/" between the AttributeValueAssertions (AVAs) that specify the members
of the set. Example:
"/DC=org/DC=OpenSSL/DC=users/UID=123456+CN=John Doe"
-utf8
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.
-create_serial
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.
-rand_serial
Generate a large random number to use as the serial number. This overrides any option or
configuration to use a serial number file.
-multivalue-rdn
This option has been deprecated and has no effect.
-rand files, -writerand file
See "Random State Options" in openssl(1) for details.
-engine id
See "Engine Options" in openssl(1). This option is deprecated.
-provider name
-provider-path path
-provparam [name:]key=value
-propquery propq
See "Provider Options" in openssl(1), provider(7), and property(7).
CRL OPTIONS
-gencrl
This option generates a CRL based on information in the index file.
-crl_lastupdate time
Allows the value of the CRL's lastUpdate field to be explicitly set; if this option is not
present, the current time is used. Accepts times in YYMMDDHHMMSSZ format (the same as an ASN1
UTCTime structure) or YYYYMMDDHHMMSSZ format (the same as an ASN1 GeneralizedTime structure).
-crl_nextupdate time
Allows the value of the CRL's nextUpdate field to be explicitly set; if this option is present,
any values given for -crldays, -crlhours and -crlsec are ignored. Accepts times in the same
formats as -crl_lastupdate.
-crldays num
The number of days before the next CRL is due. That is the days from now to place in the CRL
nextUpdate field.
-crlhours num
The number of hours before the next CRL is due.
-crlsec num
The number of seconds before the next CRL is due.
-revoke filename
A filename containing a certificate to revoke.
-valid filename
A filename containing a certificate to add a Valid certificate entry.
-status serial
Displays the revocation status of the certificate with the specified serial number and exits.
-updatedb
Updates the database index to purge expired certificates.
-crl_reason reason
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.
-crl_hold instruction
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.
-crl_compromise time
This sets the revocation reason to keyCompromise and the compromise time to time. time should be
in GeneralizedTime format that is YYYYMMDDHHMMSSZ.
-crl_CA_compromise time
This is the same as crl_compromise except the revocation reason is set to CACompromise.
-crlexts section
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.
CONFIGURATION FILE OPTIONS
The section of the configuration file containing options for this command 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.
oid_file
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 whitespace then the short name
followed by whitespace and finally the long name.
oid_section
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.
new_certs_dir
The same as the -outdir command line option. It specifies the directory where new certificates
will be placed. Mandatory.
certificate
The same as -cert. It gives the file containing the CA certificate. Mandatory.
private_key
Same as the -keyfile option. The file containing the CA private key. Mandatory.
RANDFILE
At startup the specified file is loaded into the random number generator, and at exit 256 bytes
will be written to it. (Note: Using a RANDFILE is not necessary anymore, see the "HISTORY"
section.
default_days
The same as the -days option. The number of days from today to certify a certificate for.
default_startdate
The same as the -startdate option. The start date to certify a certificate for. If not set the
current time is used.
default_enddate
The same as the -enddate option. Either this option or default_days (or the command line
equivalents) must be present.
default_crl_hours default_crl_days
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.
default_md
The same as the -md option. Mandatory except where the signing algorithm does not require a
digest (i.e. Ed25519 and Ed448).
database
The text database file to use. Mandatory. This file must be present though initially it will be
empty.
unique_subject
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.
serial
A text file containing the next serial number to use in hex. Mandatory. This file must be
present and contain a valid serial number.
crlnumber
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.
x509_extensions
A fallback to the -extensions option.
crl_extensions
A fallback to the -crlexts option.
preserve
The same as -preserveDN
email_in_dn
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.
msie_hack
The same as -msie_hack
policy
The same as -policy. Mandatory. See the POLICY FORMAT section for more information.
name_opt, cert_opt
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.
copy_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.
POLICY FORMAT
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.
SPKAC FORMAT
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 openssl-spkac(1).
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.
EXAMPLES
Note: these examples assume that the directory structure this command assumes is already set up and
the relevant files already exist. This usually involves creating a CA certificate and private key
with openssl-req(1), 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 an SM2 certificate request:
openssl ca -in sm2.csr -out sm2.crt -md sm3 \
-sigopt "distid:1234567812345678" \
-vfyopt "distid:1234567812345678"
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 this command:
[ 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
default_days = 365 # how long to certify for
default_crl_days= 30 # how long before next CRL
default_md = sha256 # md to use
policy = policy_any # default policy
email_in_dn = no # Don't add the email into cert DN
name_opt = ca_default # Subject name display option
cert_opt = ca_default # Certificate display option
copy_extensions = none # Don't copy extensions from request
[ policy_any ]
countryName = supplied
stateOrProvinceName = optional
organizationName = optional
organizationalUnitName = optional
commonName = supplied
emailAddress = optional
FILES
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
RESTRICTIONS
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.
BUGS
This command is quirky and at times downright unfriendly.
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.
This command really needs rewriting or the required functionality exposed at either a command or
interface level so that a more user-friendly replacement could 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.
WARNINGS
This command was originally meant as an example of how to do things in a CA. Its code does not have
production quality. It was not supposed to be used as a full blown CA itself, nevertheless some
people are using it for this purpose at least internally. When doing so, specific care should be
taken to properly secure the private key(s) used for signing certificates. It is advisable to keep
them in a secure HW storage such as a smart card or HSM and access them via a suitable engine or
crypto provider.
This command is effectively a single user command: no locking is done on the various files and
attempts to run more than one openssl 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.
HISTORY
Since OpenSSL 1.1.1, the program follows RFC5280. Specifically, certificate validity period
(specified by any of -startdate, -enddate and -days) and CRL last/next update time (specified by any
of -crl_lastupdate, -crl_nextupdate, -crldays, -crlhours and -crlsec) 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.
OpenSSL 1.1.1 introduced a new random generator (CSPRNG) with an improved seeding mechanism. The new
seeding mechanism makes it unnecessary to define a RANDFILE for saving and restoring randomness. This
option is retained mainly for compatibility reasons.
The -section option was added in OpenSSL 3.0.0.
The -multivalue-rdn option has become obsolete in OpenSSL 3.0.0 and has no effect.
The -engine option was deprecated in OpenSSL 3.0.
Since OpenSSL 3.2, generated certificates bear X.509 version 3, and key identifier extensions are
included by default.
SEE ALSO
openssl(1), openssl-req(1), openssl-spkac(1), openssl-x509(1), CA.pl(1), config(5), x509v3_config(5)
COPYRIGHT
Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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 .
3.5.5 2026-01-27 OPENSSL-CA(1SSL)