The req command primarily creates and processes certificate requests
in PKCS#10 format. It can additionally create self signed certificates
for use as root CAs for example.
COMMAND OPTIONS
-inform DER|PEM
This specifies the input format. The DER option uses an ASN1 DER encoded
form compatible with the PKCS#10. The PEM form is the default format: it
consists of the DER format base64 encoded with additional header and
footer lines.
-outform DER|PEM
This specifies the output format, the options have the same meaning as the
-inform option.
-in filename
This specifies the input filename to read a request from or standard input
if this option is not specified. A request is only read if the creation
options (-new and -newkey) are not specified.
-passin arg
the input file password source. For more information about the format of arg
see the PASSPHRASEARGUMENTS section in openssl(1).
-out filename
This specifies the output filename to write to or standard output by
default.
-passout arg
the output file password source. For more information about the format of arg
see the PASSPHRASEARGUMENTS section in openssl(1).
-text
prints out the certificate request in text form.
-noout
this option prevents output of the encoded version of the request.
-modulus
this option prints out the value of the modulus of the public key
contained in the request.
-verify
verifies the signature on the request.
-new
this option generates a new certificate request. It will prompt
the user for the relevant field values. The actual fields
prompted for and their maximum and minimum sizes are specified
in the configuration file and any requested extensions.
If the -key option is not used it will generate a new RSA private
key using information specified in the configuration file.
-rand file(s)
a file or files containing random data used to seed the random number
generator, or an EGD socket (see RAND_egd(3)).
Multiple files can be specified separated by a OS-dependent character.
The separator is ; for MS-Windows, , for OpenVMS, and : for
all others.
-newkey arg
this option creates a new certificate request and a new private
key. The argument takes one of two forms. rsa:nbits, where
nbits is the number of bits, generates an RSA key nbits
in size. dsa:filename generates a DSA key using the parameters
in the file filename.
-key filename
This specifies the file to read the private key from. It also
accepts PKCS#8 format private keys for PEM format files.
-keyform PEM|DER
the format of the private key file specified in the -key
argument. PEM is the default.
-keyout filename
this gives the filename to write the newly created private key to.
If this option is not specified then the filename present in the
configuration file is used.
-nodes
if this option is specified then if a private key is created it
will not be encrypted.
-[md5|sha1|md2|mdc2]
this specifies the message digest to sign the request with. This
overrides the digest algorithm specified in the configuration file.
This option is ignored for DSA requests: they always use SHA1.
-config filename
this allows an alternative configuration file to be specified,
this overrides the compile time filename or any specified in
the OPENSSL_CONF environment variable.
-x509
this option outputs a self signed certificate instead of a certificate
request. This is typically used to generate a test certificate or
a self signed root CA. The extensions added to the certificate
(if any) are specified in the configuration file.
-days n
when the -x509 option is being used this specifies the number of
days to certify the certificate for. The default is 30 days.
-extensions section
-reqexts section
these options specify alternative sections to include certificate
extensions (if the -x509 option is present) or certificate
request extensions. This allows several different sections to
be used in the same configuration file to specify requests for
a variety of purposes.
-asn1-kludge
by default the req command outputs certificate requests containing
no attributes in the correct PKCS#10 format. However certain CAs will only
accept requests containing no attributes in an invalid form: this
option produces this invalid format.
More precisely the Attributes in a PKCS#10 certificate request
are defined as a SETOF Attribute. They are not OPTIONAL so
if no attributes are present then they should be encoded as an
empty SETOF. The invalid form does not include the empty
SETOF whereas the correct form does.
It should be noted that very few CAs still require the use of this option.
-newhdr
Adds the word NEW to the PEM file header and footer lines on the outputed
request. Some software (Netscape certificate server) and some CAs need this.
CONFIGURATION FILE FORMAT
The configuration options are specified in the req section of
the configuration file. As with all configuration files if no
value is specified in the specific section (i.e. req) then
the initial unnamed or default section is searched too.
The options available are described in detail below.
input_password output_password
The passwords for the input private key file (if present) and
the output private key file (if one will be created). The
command line options passin and passout override the
configuration file values.
default_bits
This specifies the default key size in bits. If not specified then
512 is used. It is used if the -new option is used. It can be
overridden by using the -newkey option.
default_keyfile
This is the default filename to write a private key to. If not
specified the key is written to standard output. This can be
overridden by the -keyout option.
oid_file
This specifies a file containing additional OBJECTIDENTIFIERS.
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.
RANDFILE
This specifies a filename in which random number seed information is
placed and read from, or an EGD socket (see RAND_egd(3)).
It is used for private key generation.
encrypt_key
If this is set to no then if a private key is generated it is
not encrypted. This is equivalent to the -nodes command line
option. For compatibility encrypt_rsa_key is an equivalent option.
default_md
This option specifies the digest algorithm to use. Possible values
include md5 sha1 mdc2. If not present then MD5 is used. This
option can be overridden on the command line.
string_mask
This option masks out the use of certain string types in certain
fields. Most users will not need to change this option.
It can be set to several values default which is also the default
option uses PrintableStrings, T61Strings and BMPStrings if the
pkix value is used then only PrintableStrings and BMPStrings will
be used. This follows the PKIX recommendation in RFC2459. If the
utf8only option is used then only UTF8Strings will be used: this
is the PKIX recommendation in RFC2459 after 2003. Finally the nombstr
option just uses PrintableStrings and T61Strings: certain software has
problems with BMPStrings and UTF8Strings: in particular Netscape.
req_extensions
this specifies the configuration file section containing a list of
extensions to add to the certificate request. It can be overridden
by the -reqexts command line switch.
x509_extensions
this specifies the configuration file section containing a list of
extensions to add to certificate generated when the -x509 switch
is used. It can be overridden by the -extensions command line switch.
prompt
if set to the value no this disables prompting of certificate fields
and just takes values from the config file directly. It also changes the
expected format of the distinguished_name and attributes sections.
attributes
this specifies the section containing any request attributes: its format
is the same as distinguished_name. Typically these may contain the
challengePassword or unstructuredName types. They are currently ignored
by OpenSSL's request signing utilities but some CAs might want them.
distinguished_name
This specifies the section containing the distinguished name fields to
prompt for when generating a certificate or certificate request. The format
is described in the next section.
DISTINGUISHED NAME AND ATTRIBUTE SECTION FORMAT
There are two separate formats for the distinguished name and attribute
sections. If the prompt option is set to no then these sections
just consist of field names and values: for example,
This allows external programs (e.g. GUI based) to generate a template file
with all the field names and values and just pass it to req. An example
of this kind of configuration file is contained in the EXAMPLES section.
Alternatively if the prompt option is absent or not set to no then the
file contains field prompting information. It consists of lines of the form:
fieldName="prompt"
fieldName_default="default field value"
fieldName_min= 2
fieldName_max= 4
``fieldName'' is the field name being used, for example commonName (or CN).
The ``prompt'' string is used to ask the user to enter the relevant
details. If the user enters nothing then the default value is used if no
default value is present then the field is omitted. A field can
still be omitted if a default value is present if the user just
enters the `.' character.
The number of characters entered must be between the fieldName_min and
fieldName_max limits: there may be additional restrictions based
on the field being used (for example countryName can only ever be
two characters long and must fit in a PrintableString).
Some fields (such as organizationName) can be used more than once
in a DN. This presents a problem because configuration files will
not recognize the same name occurring twice. To avoid this problem
if the fieldName contains some characters followed by a full stop
they will be ignored. So for example a second organizationName can
be input by calling it ``1.organizationName''.
The actual permitted field names are any object identifier short or
long names. These are compiled into OpenSSL and include the usual
values such as commonName, countryName, localityName, organizationName,
organizationUnitName, stateOrPrivinceName. Additionally emailAddress
is include as well as name, surname, givenName initials and dnQualifier.
Additional object identifiers can be defined with the oid_file or
oid_section options in the configuration file. Any additional fields
will be treated as though they were a DirectoryString.
EXAMPLES
Examine and verify certificate request:
openssl req -in req.pem -text -verify -noout
Create a private key and then generate a certificate request from it:
[ req_distinguished_name ]
C = GB
ST = Test State or Province
L = Test Locality
O = Organization Name
OU = Organizational Unit Name
CN = Common Name
emailAddress = test@email.address
[ req_attributes ]
challengePassword = A challenge password
NOTES
The header and footer lines in the PEM format are normally:
some software (some versions of Netscape certificate server) instead needs:
-----BEGIN NEW CERTIFICATE REQUEST----
-----END NEW CERTIFICATE REQUEST----
which is produced with the -newhdr option but is otherwise compatible.
Either form is accepted transparently on input.
The certificate requests generated by Xenroll with MSIE have extensions
added. It includes the keyUsage extension which determines the type of
key (signature only or general purpose) and any additional OIDs entered
by the script in an extendedKeyUsage extension.
DIAGNOSTICS
The following messages are frequently asked about:
Using configuration from /some/path/openssl.cnf
Unable to load config info
This is followed some time later by...
unable to find 'distinguished_name' in config
problems making Certificate Request
The first error message is the clue: it can't find the configuration
file! Certain operations (like examining a certificate request) don't
need a configuration file so its use isn't enforced. Generation of
certificates or requests however does need a configuration file. This
could be regarded as a bug.
Another puzzling message is this:
Attributes:
a0:00
this is displayed when no attributes are present and the request includes
the correct empty SET OF structure (the DER encoding of which is 0xa0
0x00). If you just see:
Attributes:
then the SET OF is missing and the encoding is technically invalid (but
it is tolerated). See the description of the command line option -asn1-kludge
for more information.
ENVIRONMENT VARIABLES
The variable OPENSSL_CONF if defined allows an alternative configuration
file location to be specified, it will be overridden by the -config command
line switch if it is present. For compatibility reasons the SSLEAY_CONF
environment variable serves the same purpose but its use is discouraged.
BUGS
OpenSSL's handling of T61Strings (aka TeletexStrings) is broken: it effectively
treats them as ISO-8859-1 (Latin 1), Netscape and MSIE have similar behaviour.
This can cause problems if you need characters that aren't available in
PrintableStrings and you don't want to or can't use BMPStrings.
As a consequence of the T61String handling the only correct way to represent
accented characters in OpenSSL is to use a BMPString: unfortunately Netscape
currently chokes on these. If you have to use accented characters with Netscape
and MSIE then you currently need to use the invalid T61String form.
The current prompting is not very friendly. It doesn't allow you to confirm what
you've just entered. Other things like extensions in certificate requests are
statically defined in the configuration file. Some of these: like an email
address in subjectAltName should be input by the user.
