CA(1) OpenSSL CA(1)
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] [-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 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 section 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 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). 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 insensitive. 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 GeneralizedTime 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.
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.
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.
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 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/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
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
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
./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: however 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_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 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
req(1), spkac(1), x509(1), CA.pl(1), config(5)
0.9.7l 2005-05-23 CA(1)
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