openssl-req, req - PKCS#10 certificate request and certificate generating utility
openssl req [-help] [-inform PEM|DER] [-outform PEM|DER] [-in filename] [-passin arg] [-out filename] [-passout arg] [-text] [-pubkey] [-noout] [-verify] [-modulus] [-new] [-rand file...] [-writerand file] [-newkey rsa:bits] [-newkey alg:file] [-nodes] [-key filename] [-keyform PEM|DER] [-keyout filename] [-keygen_engine id] [-digest] [-config filename] [-multivalue-rdn] [-x509] [-days n] [-set_serial n] [-newhdr] [-addext ext] [-extensions section] [-reqexts section] [-precert] [-utf8] [-nameopt] [-reqopt] [-subject] [-subj arg] [-sigopt nm:v] [-batch] [-verbose] [-engine id]
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.
If the -key option is not used it will generate a new RSA private key using information specified in the configuration file.
All other algorithms support the -newkey alg:file form, where file may be an algorithm parameter file, created by the genpkey -genparam command or and 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 use algorithm algname and parameter file file: the two algorithms must match or an error occurs. algname just uses algorithm algname, and parameters, if necessary should be specified via -pkeyopt parameter.
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 ccgost engine configured in the configuration file). If just gost2001 is specified a parameter set should be specified by -pkeyopt paramset:X
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.
If -multi-rdn is not used then the UID value is 123456+CN=John Doe.
If existing request is specified with the -in option, it is converted to the self signed certificate otherwise new request is created.
This option can be given multiple times.
This implies the -new flag.
See discussion of the -certopt parameter in the x509(1) command.
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.
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.
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.
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 emailAddressemail@example.com
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, 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.
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
Example of a file pointed to by the oid_file option:
220.127.116.11 shortName A longer Name 18.104.22.168 otherName Other longer Name
Example of a section pointed to by oid_section making use of variable expansion:
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:
RANDFILE = $ENV::HOME/.rnd [ 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 = firstname.lastname@example.org [ 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 = 22.214.171.124" \ -newkey rsa:2048 -keyout key.pem -out req.pem
The header and footer lines in the PEM format are normally:
-----BEGIN CERTIFICATE REQUEST----- -----END CERTIFICATE REQUEST-----
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.
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:
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:
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.
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.
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Licensed under the OpenSSL license (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>.