CA(1) 23/May/2005 (0.9.7m) 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)
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