CA(1) OpenSSL CA(1)NAMEca - sample minimal CA application
openssl ca [-verbose] [-config filename] [-name section] [-gencrl]
[-revoke file] [-crl_reason reason] [-crl_hold instruction] [-crl_com‐
promise time] [-crl_CA_compromise time] [-subj arg] [-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] [-noemailDN]
[-batch] [-msie_hack] [-extensions section] [-extfile section] [-engine
The ca command is a minimal CA application. It can be used to sign cer‐
tificate requests in a variety of forms and generate CRLs it also main‐
tains a text database of issued certificates and their status.
The options descriptions will be divided into each purpose.
CA OPTIONS-config filename
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 SPKAC
FORMAT 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
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 PHRASE ARGUMENTS section in openssl(1).
this prints extra details about the operations being performed.
don't output the text form of a certificate to the output file.
this allows the start date to be explicitly set. The format of the
date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure).
this allows the expiry 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.
the message digest to use. Possible values include md5, sha1 and
mdc2. 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 manda‐
tory or match the CA certificate. Check out the POLICY FORMAT sec‐
tion for more information.
this is a legacy option to make ca work with very old versions of
the IE certificate enrollment control "certenr3". It used Univer‐
salStrings 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 compati‐
bility 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 behav‐
this 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 exten‐
sions to be added when a certificate is issued (defaults to
x509_extensions unless the -extfile option is used). If no exten‐
sion section is present then, a V1 certificate is created. If the
extension section is present (even if it is empty), then a V3 cer‐
tificate is created.
an additional configuration file to read certificate extensions
from (using the default section unless the -extensions option is
specifying an engine (by it's unique id string) will cause req 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.
this option 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 nextUpdate field.
the number of hours before the next CRL is due.
a filename containing a certificate to revoke.
revocation reason, where reason is one of: unspecified, keyCompro‐
mise, CACompromise, affiliationChanged, superseded, cessationOfOp‐
eration, certificateHold or removeFromCRL. The matching of reason
is case insensitive. Setting any revocation reason will make the
In practive 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 dis‐
couraged by RFC2459) holdInstructionCallIssuer or holdInstruction‐
Reject will normally be used.
This sets the revocation reason to keyCompromise and the compromise
time to time. time should be in GeneralizedTime format that is
This is the same as crl_compromise except the revocation reason is
set to CACompromise.
supersedes subject name given in the request. The arg must be for‐
matted as /type0=value0/type1=value1/type2=..., characters may be
escaped by \ (backslash), no spaces are skipped.
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.
CONFIGURATION FILE OPTIONS
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 sec‐
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 fol‐
lowed 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 -outdir command line option. It specifies the
directory where new certificates will be placed. Mandatory.
the same as -cert. It gives the file containing the CA certificate.
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 cer‐
the same as the -startdate option. The start date to certify a cer‐
tificate 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. Manda‐
tory. This file must be present and contain a valid serial number.
the same as -extensions.
the same as -crlexts.
the same as -preserveDN
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 certifi‐
the same as -msie_hack
the same as -policy. Mandatory. See the POLICY FORMAT section for
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 signa‐
ture cannot be displayed because the certificate has not been
signed at this point).
For convenience the values ca_default are accepted by both to pro‐
duce 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 exten‐
determines how extensions in certificate requests should be han‐
dled. 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 exten‐
sions in the request are copied to the certificate: if the exten‐
sion 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 cer‐
tificate 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 cre‐
ate 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 '.'.
Note: these examples assume that the ca directory structure is already
set up and the relevant files already exist. This usually involves cre‐
ating 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/pri‐
vate/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
email_in_dn = no # Don't add the email into cert DN
nameopt = ca_default # Subject name display option
certopt = 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
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
OPENSSL_CONF reflects the location of master configuration file it can
be overridden by the -config command line option.
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 CRL support and CRL numbers are not cur‐
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.
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 eas‐
ily be fixed without introducing other problems. Some S/MIME clients
can use two certificates with the same DN for separate signing and
The ca command really needs rewriting or the required functionality
exposed at either a command or interface level so a more friendly util‐
ity (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. 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 config‐
Cancelling some commands by refusing to certify a certificate can cre‐
ate 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: nev‐
ertheless 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 requestor 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
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.
SEE ALSOreq(1), spkac(1), x509(1), CA.pl(1), config(5)0.9.7d 2003-11-20 CA(1)