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OPENSSL-REQ(1SSL) OpenSSL OPENSSL-REQ(1SSL)
NAME
openssl-req - PKCS#10 certificate request and certificate generating command
SYNOPSIS
openssl req [-help] [-inform DER|PEM] [-outform DER|PEM] [-in filename] [-passin arg]
[-out filename] [-passout arg] [-text] [-pubkey] [-noout] [-verify] [-modulus] [-new]
[-newkey arg] [-pkeyopt opt:value] [-noenc] [-nodes] [-key filename|uri] [-keyform
DER|PEM|P12|ENGINE] [-keyout filename] [-keygen_engine id] [-digest] [-config filename]
[-section name] [-x509] [-CA filename|uri] [-CAkey filename|uri] [-days n] [-set_serial n]
[-newhdr] [-copy_extensions arg] [-addext ext] [-extensions section] [-reqexts section]
[-precert] [-utf8] [-reqopt] [-subject] [-subj arg] [-multivalue-rdn] [-sigopt nm:v]
[-vfyopt nm:v] [-batch] [-verbose] [-nameopt option] [-rand files] [-writerand file]
[-engine id] [-provider name] [-provider-path path] [-propquery propq]
DESCRIPTION
This command primarily creates and processes certificate requests (CSRs) in PKCS#10
format. It can additionally create self-signed certificates for use as root CAs for
example.
OPTIONS
-help
Print out a usage message.
-inform DER|PEM, -outform DER|PEM
The input and output formats; unspecified by default. See openssl-format-options(1)
for details.
The data is a PKCS#10 object.
-in filename
This specifies the input filename to read a request from. This defaults to standard
input unless -x509 or -CA is specified. A request is only read if the creation
options (-new or -newkey or -precert) are not specified.
-sigopt nm:v
Pass options to the signature algorithm during sign operations. Names and values of
these options are algorithm-specific.
-vfyopt nm:v
Pass options to the signature algorithm during verify operations. Names and values of
these options are algorithm-specific.
-passin arg
The password source for private key and certificate input. For more information about
the format of arg see openssl-passphrase-options(1).
-passout arg
The password source for the output file. For more information about the format of arg
see openssl-passphrase-options(1).
-out filename
This specifies the output filename to write to or standard output by default.
-text
Prints out the certificate request in text form.
-subject
Prints out the certificate request subject (or certificate subject if -x509 is in
use).
-pubkey
Prints out the public key.
-noout
This option prevents output of the encoded version of the certificate request.
-modulus
Prints out the value of the modulus of the public key contained in the request.
-verify
Verifies the self-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 given it will generate a new private key using information
specified in the configuration file or given with the -newkey and -pkeyopt options,
else by default an RSA key with 2048 bits length.
-newkey arg
This option is used to generate a new private key unless -key is given. It is
subsequently used as if it was given using the -key option.
This option implies the -new flag to create a new certificate request or a new
certificate in case -x509 is given.
The argument takes one of several forms.
[rsa:]nbits generates an RSA key nbits in size. If nbits is omitted, i.e., -newkey
rsa is specified, the default key size specified in the configuration file with the
default_bits option is used if present, else 2048.
All other algorithms support the -newkey algname:file form, where file is an algorithm
parameter file, created with "openssl genpkey -genparam" or an X.509 certificate for a
key with appropriate algorithm.
param:file generates a key using the parameter file or certificate file, the algorithm
is determined by the parameters.
algname[:file] generates a key using the given algorithm algname. If a parameter file
file is given then the parameters specified there are used, where the algorithm
parameters must match algname. If algorithm parameters are not given, any necessary
parameters should be specified via the -pkeyopt option.
dsa:filename generates a DSA key using the parameters in the file filename.
ec:filename generates EC key (usable both with ECDSA or ECDH algorithms),
gost2001:filename generates GOST R 34.10-2001 key (requires gost engine configured in
the configuration file). If just gost2001 is specified a parameter set should be
specified by -pkeyopt paramset:X
-pkeyopt opt:value
Set the public key algorithm option opt to value. The precise set of options supported
depends on the public key algorithm used and its implementation. See "KEY GENERATION
OPTIONS" in openssl-genpkey(1) for more details.
-key filename|uri
This option provides the private key for signing a new certificate or certificate
request. Unless -in is given, the corresponding public key is placed in the new
certificate or certificate request, resulting in a self-signature.
For certificate signing this option is overridden by the -CA option.
This option also accepts PKCS#8 format private keys for PEM format files.
-keyform DER|PEM|P12|ENGINE
The format of the private key; unspecified by default. See openssl-format-options(1)
for details.
-keyout filename
This gives the filename to write any private key to that has been newly created or
read from -key. If neither the -keyout option nor the -key option are given then the
filename specified in the configuration file with the default_keyfile option is used,
if present. Thus, if you want to write the private key and the -key option is
provided, you should provide the -keyout option explicitly. If a new key is generated
and no filename is specified the key is written to standard output.
-noenc
If this option is specified then if a private key is created it will not be encrypted.
-nodes
This option is deprecated since OpenSSL 3.0; use -noenc instead.
-digest
This specifies the message digest to sign the request. Any digest supported by the
OpenSSL dgst command can be used. This overrides the digest algorithm specified in
the configuration file.
Some public key algorithms may override this choice. For instance, DSA signatures
always use SHA1, GOST R 34.10 signatures always use GOST R 34.11-94 (-md_gost94),
Ed25519 and Ed448 never use any digest.
-config filename
This allows an alternative configuration file to be specified. Optional; for a
description of the default value, see "COMMAND SUMMARY" in openssl(1).
-section name
Specifies the name of the section to use; the default is req.
-subj arg
Sets subject name for new request or supersedes the subject name when processing a
certificate request.
The arg must be formatted as "/type0=value0/type1=value1/type2=...". Special
characters may be escaped by "\" (backslash), whitespace is retained. Empty values
are permitted, but the corresponding type will not be included in the request. Giving
a single "/" will lead to an empty sequence of RDNs (a NULL-DN). Multi-valued RDNs
can be formed by placing a "+" character instead of a "/" between the
AttributeValueAssertions (AVAs) that specify the members of the set. Example:
"/DC=org/DC=OpenSSL/DC=users/UID=123456+CN=John Doe"
-multivalue-rdn
This option has been deprecated and has no effect.
-x509
This option outputs a certificate instead of a certificate request. This is typically
used to generate test certificates. It is implied by the -CA option.
This option implies the -new flag if -in is not given.
If an existing request is specified with the -in option, it is converted to the a
certificate; otherwise a request is created from scratch.
Unless specified using the -set_serial option, a large random number will be used for
the serial number.
Unless the -copy_extensions option is used, X.509 extensions are not copied from any
provided request input file.
X.509 extensions to be added can be specified in the configuration file or using the
-addext option.
-CA filename|uri
Specifies the "CA" certificate to be used for signing a new certificate and implies
use of -x509. When present, this behaves like a "micro CA" as follows: The subject
name of the "CA" certificate is placed as issuer name in the new certificate, which is
then signed using the "CA" key given as specified below.
-CAkey filename|uri
Sets the "CA" private key to sign a certificate with. The private key must match the
public key of the certificate given with -CA. If this option is not provided then the
key must be present in the -CA input.
-days n
When -x509 is in use this specifies the number of days to certify the certificate for,
otherwise it is ignored. n should be a positive integer. The default is 30 days.
-set_serial n
Serial number to use when outputting a self-signed certificate. This may be specified
as a decimal value or a hex value if preceded by "0x". If not given, a large random
number will be used.
-copy_extensions arg
Determines how X.509 extensions in certificate requests should be handled when -x509
is in use. If arg is none or this option is not present then extensions are ignored.
If arg is copy or copyall then all extensions in the request are copied to the
certificate.
The main use of this option is to allow a certificate request to supply values for
certain extensions such as subjectAltName.
-addext ext
Add a specific extension to the certificate (if -x509 is in use) or certificate
request. The argument must have the form of a key=value pair as it would appear in a
config file.
This option can be given multiple times.
-extensions section
-reqexts section
These options specify alternative sections to include certificate extensions (if -x509
is in use) 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.
-precert
A poison extension will be added to the certificate, making it a "pre-certificate"
(see RFC6962). This can be submitted to Certificate Transparency logs in order to
obtain signed certificate timestamps (SCTs). These SCTs can then be embedded into the
pre-certificate as an extension, before removing the poison and signing the
certificate.
This implies the -new flag.
-utf8
This option causes field values to be interpreted as UTF8 strings, by default they are
interpreted as ASCII. This means that the field values, whether prompted from a
terminal or obtained from a configuration file, must be valid UTF8 strings.
-reqopt option
Customise the printing format used with -text. The option argument can be a single
option or multiple options separated by commas.
See discussion of the -certopt parameter in the openssl-x509(1) command.
-newhdr
Adds the word NEW to the PEM file header and footer lines on the outputted request.
Some software (Netscape certificate server) and some CAs need this.
-batch
Non-interactive mode.
-verbose
Print extra details about the operations being performed.
-keygen_engine id
Specifies an engine (by its unique id string) which would be used for key generation
operations.
-nameopt option
This specifies how the subject or issuer names are displayed. See
openssl-namedisplay-options(1) for details.
-rand files, -writerand file
See "Random State Options" in openssl(1) for details.
-engine id
See "Engine Options" in openssl(1). This option is deprecated.
-provider name
-provider-path path
-propquery propq
See "Provider Options" in openssl(1), provider(7), and property(7).
CONFIGURATION FILE FORMAT
The configuration options are specified in the req section of the configuration file. An
alternate name be specified by using the -section option. As with all configuration
files, if no value is specified in the specific section 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
Specifies the default key size in bits.
This option is used in conjunction with the -new option to generate a new key. It can
be overridden by specifying an explicit key size in the -newkey option. The smallest
accepted key size is 512 bits. If no key size is specified then 2048 bits is used.
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 OBJECT IDENTIFIERS. Each line of the file
should consist of the numerical form of the object identifier followed by whitespace
then the short name followed by whitespace 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
At startup the specified file is loaded into the random number generator, and at exit
256 bytes will be written to it. 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 -noenc command line option. For compatibility encrypt_rsa_key is an
equivalent option.
default_md
This option specifies the digest algorithm to use. Any digest supported by the OpenSSL
dgst command can be used. This option can be overridden on the command line. Certain
signing algorithms (i.e. Ed25519 and Ed448) will ignore any digest that has been set.
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.
See the x509v3_config(5) manual page for details of the extension section format.
x509_extensions
This specifies the configuration file section containing a list of extensions to add
to certificate generated when -x509 is in use. 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.
utf8
If set to the value yes then field values to be interpreted as UTF8 strings, by
default they are interpreted as ASCII. This means that the field values, whether
prompted from a terminal or obtained from a configuration file, must be valid UTF8
strings.
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,
CN=My Name
OU=My Organization
emailAddress=someone AT somewhere.org
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 this command. 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, organizationalUnitName, stateOrProvinceName. Additionally
emailAddress is included 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:
openssl genrsa -out key.pem 2048
openssl req -new -key key.pem -out req.pem
The same but just using req:
openssl req -newkey rsa:2048 -keyout key.pem -out req.pem
Generate a self-signed root certificate:
openssl req -x509 -newkey rsa:2048 -keyout key.pem -out req.pem
Create an SM2 private key and then generate a certificate request from it:
openssl ecparam -genkey -name SM2 -out sm2.key
openssl req -new -key sm2.key -out sm2.csr -sm3 -sigopt "distid:1234567812345678"
Examine and verify an SM2 certificate request:
openssl req -verify -in sm2.csr -sm3 -vfyopt "distid:1234567812345678"
Example of a file pointed to by the oid_file option:
1.2.3.4 shortName A longer Name
1.2.3.6 otherName Other longer Name
Example of a section pointed to by oid_section making use of variable expansion:
testoid1=1.2.3.5
testoid2=${testoid1}.6
Sample configuration file prompting for field values:
[ req ]
default_bits = 2048
default_keyfile = privkey.pem
distinguished_name = req_distinguished_name
attributes = req_attributes
req_extensions = v3_ca
dirstring_type = nobmp
[ req_distinguished_name ]
countryName = Country Name (2 letter code)
countryName_default = AU
countryName_min = 2
countryName_max = 2
localityName = Locality Name (eg, city)
organizationalUnitName = Organizational Unit Name (eg, section)
commonName = Common Name (eg, YOUR name)
commonName_max = 64
emailAddress = Email Address
emailAddress_max = 40
[ req_attributes ]
challengePassword = A challenge password
challengePassword_min = 4
challengePassword_max = 20
[ v3_ca ]
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid:always,issuer:always
basicConstraints = critical, CA:true
Sample configuration containing all field values:
[ req ]
default_bits = 2048
default_keyfile = keyfile.pem
distinguished_name = req_distinguished_name
attributes = req_attributes
prompt = no
output_password = mypass
[ 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 AT email.address
[ req_attributes ]
challengePassword = A challenge password
Example of giving the most common attributes (subject and extensions) on the command line:
openssl req -new -subj "/C=GB/CN=foo" \
-addext "subjectAltName = DNS:foo.co.uk" \
-addext "certificatePolicies = 1.2.3.4" \
-newkey rsa:2048 -keyout key.pem -out req.pem
NOTES
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.
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.
SEE ALSO
openssl(1), openssl-x509(1), openssl-ca(1), openssl-genrsa(1), openssl-gendsa(1),
config(5), x509v3_config(5)
HISTORY
The -section option was added in OpenSSL 3.0.0.
The -multivalue-rdn option has become obsolete in OpenSSL 3.0.0 and has no effect.
The -engine option was deprecated in OpenSSL 3.0. The <-nodes> option was deprecated in
OpenSSL 3.0, too; use -noenc instead.
COPYRIGHT
Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use this file except
in compliance with the License. You can obtain a copy in the file LICENSE in the source
distribution or at <https://www.openssl.org/source/license.html>.
3.0.2 2025-09-18 OPENSSL-REQ(1SSL)
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