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Updated: Wednesday, July 27, 2022

req (1openssl)


req - PKCS#10 certificate request and certificate generating utility.


openssl req [-inform PEM|DER] [-outform PEM|DER] [-in filename]
[-passin arg] [-out filename] [-passout arg] [-text] [-pubkey] [-noout]
[-verify] [-modulus] [-new] [-rand file(s)] [-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] [-asn1-kludge]
[-no-asn1-kludge] [-newhdr] [-extensions section] [-reqexts section]
[-utf8] [-nameopt] [-reqopt] [-subject] [-subj arg] [-batch] [-verbose]
[-engine id]


REQ(1openssl)                       OpenSSL                      REQ(1openssl)

       openssl-req, req - PKCS#10 certificate request and certificate
       generating utility.

       openssl req [-inform PEM|DER] [-outform PEM|DER] [-in filename]
       [-passin arg] [-out filename] [-passout arg] [-text] [-pubkey] [-noout]
       [-verify] [-modulus] [-new] [-rand file(s)] [-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] [-asn1-kludge]
       [-no-asn1-kludge] [-newhdr] [-extensions section] [-reqexts section]
       [-utf8] [-nameopt] [-reqopt] [-subject] [-subj arg] [-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.

       -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 PASS PHRASE ARGUMENTS 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 PASS PHRASE ARGUMENTS section in openssl(1).

           prints out the certificate request in text form.

           prints out the request subject (or certificate subject if -x509 is

           outputs the public key.

           this option prevents output of the encoded version of the request.

           this option prints out the value of the modulus of the public key
           contained in the request.

           verifies the signature on the request.

           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.

       -subj arg
           Replaces subject field of input request with specified data and
           outputs modified request. The arg must be formatted as
           /type0=value0/type1=value1/type2=..., characters may be escaped by
           \ (backslash), no spaces are skipped.

       -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 several forms. rsa:nbits, where
           nbits is the number of bits, generates an RSA key nbits in size. If
           nbits is omitted, i.e. -newkey rsa specified, the default key size,
           specified in the configuration file is used.

           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
           approriate 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 neccessary should be specified via -pkeyopt

           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

       -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 the genpkey
           manual page for more details.

       -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.

           if this option is specified then if a private key is created it
           will not be encrypted.

           this specifies the message digest to sign the request with (such as
           -md5, -sha1). 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).

       -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.

       -subj arg
           sets subject name for new request or supersedes the subject name
           when processing a request.  The arg must be formatted as
           /type0=value0/type1=value1/type2=..., characters may be escaped by
           \ (backslash), no spaces are skipped.

           this option causes the -subj argument to be interpreted with full
           support for multivalued RDNs. Example:

           /DC=org/DC=OpenSSL/DC=users/UID=123456+CN=John Doe

           If -multi-rdn is not used then the UID value is 123456+CN=John Doe.

           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.
           Unless specified using the set_serial option, a large random number
           will be used for the serial number.

           If existing request is specified with the -in option, it is
           converted to the self signed certificate otherwise new request is

       -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.

       -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.  It is possible to use negative serial numbers but this is
           not recommended.

       -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

           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.

       -nameopt option
           option which determines how the subject or issuer names are
           displayed. The option argument can be a single option or multiple
           options separated by commas.  Alternatively the -nameopt switch may
           be used more than once to set multiple options. See the x509(1)
           manual page for details.

           customise the output format used with -text. The option argument
           can be a single option or multiple options separated by commas.

           See discission of the  -certopt parameter in the x509 command.

           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 SET OF Attribute. They are not OPTIONAL so if no
           attributes are present then they should be encoded as an empty SET
           OF. The invalid form does not include the empty SET OF whereas the
           correct form does.

           It should be noted that very few CAs still require the use of this

           Reverses effect of -asn1-kludge

           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.

           non-interactive mode.

           print extra details about the operations being performed.

       -engine id
           specifying an engine (by its 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.

       -keygen_engine id
           specifies an engine (by its unique id string) which would be used
           for key generation operations.

       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.

           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.

           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.

           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.

           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.

           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.

           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.

           This option specifies the digest algorithm to use. Possible values
           include md5 sha1 mdc2. This option can be overridden on the command

           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

           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.

           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.

           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.

           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.

           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.

           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.

       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

       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

       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

        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 include as well as name, surname, givenName initials and

       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:        shortName       A longer Name        otherName       Other longer Name

       Example of a section pointed to by oid_section making use of variable


       Sample configuration file prompting for field values:

        [ req ]
        default_bits           = 2048
        default_keyfile        = privkey.pem
        distinguished_name     = req_distinguished_name
        attributes             = req_attributes
        x509_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 ]

        basicConstraints = 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           = test@email.address

        [ req_attributes ]
        challengePassword              = A challenge password

       See attributes(7) for descriptions of the following attributes:

       |Availability   | library/security/openssl |
       |Stability      | Pass-through uncommitted |

       The header and footer lines in the PEM format are normally:


       some software (some versions of Netscape certificate server) instead


       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.

       Source code for open source software components in Oracle Solaris can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-

       This software was built from source available at
       https://github.com/oracle/solaris-userland.  The original community
       source was downloaded from

       Further information about this software can be found on the open source
       community website at https://www.openssl.org/.

       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.

       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.

       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

       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.

       x509(1), ca(1), genrsa(1), gendsa(1), config(5), x509v3_config(5)

1.0.2ze                           2022-05-03                     REQ(1openssl)