NAME
ca - sample minimal CA application
SYNOPSIS
openssl ca [-verbose] [-config filename] [-name section] [-gencrl] [-revoke file] [-crl_reason reason]
[-crl_hold instruction] [-crl_compromise time] [-crl_CA_compromise time] [-subj arg] [-crldays days] [-crl-
hours hours] [-crlexts section] [-startdate date] [-enddate date] [-days arg] [-md arg] [-policy arg] [-key-
file 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 id]
DESCRIPTION
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.
CA OPTIONS
-config filename
specifies the configuration file to use.
-name 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 to be signed by the CA.
-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 format.
-infiles
if present this should be the last option, all subsequent arguments are assumed to the 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.
-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
the CA certificate file.
-keyfile filename
the private key to sign requests with.
-key password
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.
-passin arg
the key password source. For more information about the format of arg see the PASS PHRASE ARGUMENTS sec-
tion in openssl(1).
-verbose
this prints extra details about the operations being performed.
-notext
don't output the text form of a certificate to the output file.
-startdate date
this allows the start date to be explicitly set. The format of the date is YYMMDDHHMMSSZ (the same as an
ASN1 UTCTime structure).
-enddate date
this allows the expiry date to be explicitly set. The format of the date is YYMMDDHHMMSSZ (the same as an
ASN1 UTCTime structure).
-days arg
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.
-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 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.
-preserveDN
Normally the DN order of a certificate is the same as the order of the fields in the relevant policy sec-
tion. 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 pol-
icy 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). 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.
-extfile file
an additional configuration file to read certificate extensions from (using the default section unless the
-extensions option is also used).
-engine id
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.
CRL OPTIONS
-gencrl
this option generates a CRL based on information in the index file.
-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.
-revoke filename
a filename containing a certificate to revoke.
-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 insen-
sitive. Setting any revocation reason will make the CRL v2.
In practive 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 Gener-
alizedTime format that is YYYYMMDDHHMMSSZ.
-crl_CA_compromise time
This is the same as crl_compromise except the revocation reason is set to CACompromise.
-subj arg
supersedes subject name given in the request. The arg must be formatted as
/type0=value0/type1=value1/type2=..., characters may be escaped by \ (backslash), no spaces are skipped.
-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.
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 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 white space then the short name followed by white
space 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
a file used to read and write random number seed information, or an EGD socket (see RAND_egd(3)).
default_days
the same as the -days option. The number of days 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. The message digest to use. Mandatory.
database
the text database file to use. Mandatory. This file must be present though initially it will be empty.
serialfile
a text file containing the next serial number to use in hex. Mandatory. This file must be present and
contain a valid serial number.
x509_extensions
the same as -extensions.
crl_extensions
the same as -crlexts.
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.
nameopt, certopt
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 cer-
tificate signature cannot be displayed because the certificate has not been signed at this point).
For convenience the values default_ca 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 multi-
character 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 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 '.'.
EXAMPLES
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/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):
SPKAC=MIG0MGAwXDANBgkqhkiG9w0BAQEFAANLADBIAkEAn7PDhCeV/xIxUg8V70YRxK2A5
CN=Steve Test
emailAddress=steve AT 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
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 = default_ca # Subject name display option
certopt = default_ca # 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, envi-
ronment 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
ENVIRONMENT VARIABLES
OPENSSL_CONF reflects the location of master configuration file it can be overridden by the -config command
line option.
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: how-
ever there is no option to do this.
V2 CRL features like delta CRL support and CRL numbers 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
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 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. 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.
Cancelling some commands by refusing to certify a certificate can create an empty file.
WARNINGS
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_exten-
sions 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 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.
SEE ALSO
