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.
å
-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.
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 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
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 |
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.
¾
Restrictions
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)
