openssl ca

sample minimal CA application 

openssl command


openssl ca [-verbose] [-config filename] [-name section] [-gencrl] [-revoke file] [-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] [-batch] [-msie_hack] [-extensions section]


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 

specifies an input file name containing a single certificate request to be signed by the CA.

-ss_cert filename 

specifies a single self signed certificate to be signed by the CA.

-spkac filename 

specifies a file containing a single Netscape signed public key and challenge and additional field values to be signed by the CA.


if present this should be the last option all subsequent arguments are assumed to the the names of files containing certificate requests.

-out filename 

specifies 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 

specifies the directory to output certificates to. The certificate will be written to a file name consisting of the serial number in hex with .pem appended.


specifies the CA certificate file.

-keyfile filename 

specifies the private key to sign requests with.

-key password 

specifies the password used to encrypt the private key. Since on some systems the command line arguments are visible (for example UNIX with the ps utility) this option should be used with caution.

-passin arg 

specifies the key password source. For more information about the format of arg see the PASS PHRASE ARGUMENTS section in the openssl reference page.


prints extra details about the operations being performed.


does not output the text form of a certificate to the output file.

-startdate date 

allows the start date to be explicitly set. The format of the date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure).

-enddate date 

allows the expiry date to be explicitly set. The format of the date is YYMMDDHHMMSSZ (the same as an ASN1 UTCTime structure).

-days arg 

specifies the number of days to certify the certificate for.

-md alg 

specifies the message digest to use. Possible values include md5 sha1 and mdc2. This option also applies to CRLs.

-policy arg 

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.


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.


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.


sets the batch mode. In this mode no questions will be asked and all certificates will be certified automatically.

-extensions section 

specifies the section of the configuration file containing certificate extensions to be added when a certificate is issued. 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.

CRL Options


this option generates a CRL based on information in the index file.

-crldays num 

specifies 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 

specifies the number of hours before the next CRL is due.

-revoke filename 

specifies a file name containing a certificate to revoke.

-crlexts section 

specifies 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:


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.


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.


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.


is the same as the -outdir command line option. It specifies the directory where new certificates will be placed. Mandatory.


is the same as -cert. It gives the file containing the CA certificate. Mandatory.


is the same as the -keyfile option. The file containing the CA private key. Mandatory.


is a file used to read and write random number seed information or an EGD socket.


is the same as the -days option. The number of days to certify a certificate for.


is the same as the -startdate option. The start date to certify a certificate for. If not set the current time is used.


is the same as the -enddate option. Either this option or default_days (or the char line equivalents) must be present.


is 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.


is the same as the -md option. The message digest to use. Mandatory.


is the text database file to use. Mandatory. This file must be present though initially it will be empty.


is a text file containing the next serial number to use in hex. Mandatory. This file must be present and contain a valid serial number.


is the same as -extensions.


is the same as -crlexts.


is the same as -preserveDN


is the same as -msie_hack


is the same as -policy. Mandatory. See the POLICY FORMAT section for more information.


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 behavior.


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 ..


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):

CN=Steve Test
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

[ policy_any ]
countryName            = supplied
stateOrProvinceName    = optional
organizationName       = optional
organizationalUnitName = optional
commonName             = supplied
emailAddress           = optional


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 be 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.


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.


master configuration file


main CA directory


CA certificate


CA private key


CA serial number file


CA serial number backup file


CA text database file


CA text database backup file


certificate output file


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.

CRL entry extensions cannot currently be created: only CRL extensions can be added.

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.


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.

Certificate request extensions are ignored: some kind of "policy" should be included to use certain static extensions and certain extensions from the request.

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 and 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 but the extra fields are not displayed when the user is asked to certify a request. The behavior should be more friendly and configurable.

Cancelling some commands by refusing to certify a certificate can create an empty file.


PTC MKS Toolkit for System Administrators
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PTC MKS Toolkit for Professional Developers
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PTC MKS Toolkit for Enterprise Developers 64-Bit Edition


Commands:, openssl req, openssl spkac, openssl x509

openssl config

PTC MKS Toolkit 10.0 Documentation Build 6.