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NAMEreq - PKCS#10 certificate request and certificate generating utility.
SYNOPSISopenssl 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]
DESCRIPTIONThe 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 DERoption uses anASN1 DERencoded form compatible with the PKCS#10. ThePEMform is the default format: it consists of theDERformat 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 ARGUMENTSsection 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 ARGUMENTSsection in openssl(1).
- prints out the certificate request in text form.
- prints out the request subject (or certificate subject if -x509 is specified)
- 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 newRSAprivate 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 EGDsocket (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 RSAkey 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 parameter.
dsa:filename generates aDSAkey using the parameters in the file filename. ec:filename generatesECkey (usable both withECDSAorECDHalgorithms), gost2001:filename generatesGOST R 34.10-2001key (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 OPTIONSin 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 PEMformat files.
- -keyform PEM|DER
the format of the private key file specified in the -key
argument. PEMis 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,DSAsignatures always useSHA1, GOST R 34.10signatures always useGOST 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_CONFenvironment 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:
If -multi-rdn is not used then theUIDvalue 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.
- -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 purposes.
this option causes field values to be interpreted as UTF8strings, by default they are interpreted asASCII.This means that the field values, whether prompted from a terminal or obtained from a configuration file, must be validUTF8strings.
- -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 aSET OFAttribute. They are notOPTIONALso if no attributes are present then they should be encoded as an emptySET OF. The invalid form does not include the emptySET OFwhereas the correct form does.
It should be noted that very few CAs still require the use of this option.
- Reverses effect of -asn1-kludge
Adds the word NEWto thePEMfile 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.
CONFIGURATION FILE FORMATThe 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 EGDsocket (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. If not present then MD5is used. This option can be overridden on the command line.
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 thePKIXrecommendation inRFC2459.If the utf8only option is used then only UTF8Strings will be used: this is thePKIXrecommendation inRFC2459after 2003. Finally the nombstr option just uses PrintableStrings and T61Strings: certain software has problems with BMPStrings and UTF8Strings: in particular Netscape.
- 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 UTF8strings, by default they are interpreted asASCII.This means that the field values, whether prompted from a terminal or obtained from a configuration file, must be validUTF8strings.
- 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.
DISTINGUISHED NAME AND ATTRIBUTE SECTION FORMATThere 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 emailAddressfirstname.lastname@example.org
This allows external programs (e.g.
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
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
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 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.
EXAMPLESExamine 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:
126.96.36.199 shortName A longer Name 188.8.131.52 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 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 ] subjectKeyIdentifier=hash authorityKeyIdentifier=keyid:always,issuer:always 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 = email@example.com [ req_attributes ] challengePassword = A challenge password
NOTESThe header and footer lines in the
-----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
DIAGNOSTICSThe 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
ENVIRONMENT VARIABLESThe variable
BUGSOpenSSL's handling of T61Strings (aka TeletexStrings) is broken: it effectively treats them as
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
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.