openssl_csr_new

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

openssl_csr_new — Generates a CSR

Description

openssl_csr_new(
    array $distinguished_names,
    #[\SensitiveParameter] ?OpenSSLAsymmetricKey &$private_key,
    ?array $options = null,
    ?array $extra_attributes = null
): OpenSSLCertificateSigningRequest|bool

openssl_csr_new() generates a new CSR based on the information provided by distinguished_names.

Note: You need to have a valid openssl.cnf installed for this function to operate correctly. See the notes under the installation section for more information.

Parameters

distinguished_names

The Distinguished Name or subject fields to be included in the certificate. The distinguished_names is an associative array where the keys represent the attribute names of Distinguished Names and the values can either be strings (for single value) or arrays (if multiple values need to be set).

private_key

private_key should be set to a private key that was previously generated by openssl_pkey_new() (or otherwise obtained from the other openssl_pkey family of functions), or null variable. If its value is null variable, a new private key is generated based on the supplied options and assigned to supplied variable. The corresponding public portion of the key will be used to sign the CSR.

options

By default, the information in your system openssl.conf is used to initialize the request; you can specify a configuration file section by setting the config_section_section key in options. You can also specify an alternative OpenSSL configuration file by setting the value of the config key to the path of the file you want to use. The following keys, if present in options behave as their equivalents in the openssl.conf, as listed in the table below.

**Configuration overrides**
`options` key	type	`openssl.conf` equivalent	description
digest_alg	string	default_md	Digest method or signature hash, usually one of openssl_get_md_methods()
x509_extensions	string	x509_extensions	Selects which extensions should be used when creating an x509 certificate
req_extensions	string	req_extensions	Selects which extensions should be used when creating a CSR
private_key_bits	int	default_bits	Specifies how many bits should be used to generate a private key
private_key_type	int	none	Specifies the type of private key to create. This can be one of `OPENSSL_KEYTYPE_DSA`, `OPENSSL_KEYTYPE_DH`, `OPENSSL_KEYTYPE_RSA` or `OPENSSL_KEYTYPE_EC`. The default value is `OPENSSL_KEYTYPE_RSA`.
encrypt_key	bool	encrypt_key	Should an exported key (with passphrase) be encrypted?
encrypt_key_cipher	int	none	One of cipher constants.
curve_name	string	none	One of openssl_get_curve_names().
config	string	N/A	Path to your own alternative openssl.conf file.

extra_attributes

extra_attributes is used to specify additional attributes for the CSR. It is an associative arrays where the keys are converted to OIDs and applied as CSR attributes.

Return Values

Returns the CSR on success, true if CSR creation is successful but signing fails or false on failure.

Changelog

Version	Description
8.4.0	The `distinguished_names` associative array now supports arrays as values, allowing multiple values to be specified for a single attribute.
8.4.0	The `extra_attributes` parameter now correctly sets the CSR attributes, rather than modifying the subject's Distinguished Name as it previously did incorrectly.
8.0.0	On success, this function returns an OpenSSLCertificateSigningRequest instance now; previously, a resource of type `OpenSSL X.509 CSR` was returned.
8.0.0	`private_key` accepts an OpenSSLAsymmetricKey instance now; previously, a resource of type `OpenSSL key` was accepted.
7.1.0	`options` now also supports `curve_name`.

Examples

Example #1 Creating a self-signed certificate

<?php
// for SSL server certificates the commonName is the domain name to be secured
// for S/MIME email certificates the commonName is the owner of the email address
// location and identification fields refer to the owner of domain or email subject to be secured
$dn = array(
    "countryName" => "GB",
    "stateOrProvinceName" => "Somerset",
    "localityName" => "Glastonbury",
    "organizationName" => "The Brain Room Limited",
    "organizationalUnitName" => "PHP Documentation Team",
    "commonName" => "Wez Furlong",
    "emailAddress" => "wez@example.com"
);

// Generate a new private (and public) key pair
$privkey = openssl_pkey_new(array(
    "private_key_bits" => 2048,
    "private_key_type" => OPENSSL_KEYTYPE_RSA,
));

// Generate a certificate signing request
$csr = openssl_csr_new($dn, $privkey, array('digest_alg' => 'sha256'));

// Generate a self-signed cert, valid for 365 days
$x509 = openssl_csr_sign($csr, null, $privkey, $days=365, array('digest_alg' => 'sha256'));

// Save your private key, CSR and self-signed cert for later use
openssl_csr_export($csr, $csrout) and var_dump($csrout);
openssl_x509_export($x509, $certout) and var_dump($certout);
openssl_pkey_export($privkey, $pkeyout, "mypassword") and var_dump($pkeyout);

// Show any errors that occurred here
while (($e = openssl_error_string()) !== false) {
    echo $e . "\n";
}
?>

Example #2 Creating a self-signed ECC certificate (as of PHP 7.1.0)

<?php
$subject = array(
    "commonName" => "docs.php.net",
);

// Generate a new private (and public) key pair
$private_key = openssl_pkey_new(array(
    "private_key_type" => OPENSSL_KEYTYPE_EC,
    "curve_name" => 'prime256v1',
));

// Generate a certificate signing request
$csr = openssl_csr_new($subject, $private_key, array('digest_alg' => 'sha384'));

// Generate self-signed EC cert
$x509 = openssl_csr_sign($csr, null, $private_key, $days=365, array('digest_alg' => 'sha384'));
openssl_x509_export_to_file($x509, 'ecc-cert.pem');
openssl_pkey_export_to_file($private_key, 'ecc-private.key');
?>

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User Contributed Notes 10 notes

down

The_Lost_One ¶

15 years ago

Not sure whether the "bug" (undocumented behavior) I encountered is common to other people, but this comment might save hours of painful debug:
If you can't generate a new private key using openssl_pkey_new() or openssl_csr_new(), your script hangs during the call of these functions and in case you specified a "private_key_bits" parameter, ensure that you cast the variable to an int. Took me ages to notice that.

<?php
$SSLcnf = array('config' => '/usr/local/nessy2/share/ssl/openssl.cnf',
        'encrypt_key' => true,
        'private_key_type' => OPENSSL_KEYTYPE_RSA,
        'digest_alg' => 'sha1',
        'x509_extensions' => 'v3_ca',
        'private_key_bits' => $someVariable // ---> bad
        'private_key_bits' => (int)$someVariable // ---> good
        'private_key_bits' => 512 // ---> obviously good
        );
?>

down

james at kirk dot com ¶

9 years ago

When in doubt, read the source code to PHP!

$configargs is fairly opaque as to what is going on behind the scenes.  That is, until you actually look at php_openssl_parse_config() in '/ext/openssl/openssl.c':

    SET_OPTIONAL_STRING_ARG("digest_alg", req->digest_name,
        CONF_get_string(req->req_config, req->section_name, "default_md"));
    SET_OPTIONAL_STRING_ARG("x509_extensions", req->extensions_section,
        CONF_get_string(req->req_config, req->section_name, "x509_extensions"));
    SET_OPTIONAL_STRING_ARG("req_extensions", req->request_extensions_section,
        CONF_get_string(req->req_config, req->section_name, "req_extensions"));
    SET_OPTIONAL_LONG_ARG("private_key_bits", req->priv_key_bits,
        CONF_get_number(req->req_config, req->section_name, "default_bits"));

    SET_OPTIONAL_LONG_ARG("private_key_type", req->priv_key_type, OPENSSL_KEYTYPE_DEFAULT);

Here we can see that SET_OPTIONAL_STRING_ARG() is called for most inputs but for 'private_key_bits' SET_OPTIONAL_LONG_ARG() is called.  Both calls are C macros that expand to code that enforces the expected input type.  The generated code ignores the input without warning/notice if an unexpected type is used and just uses the default from the configuration file.  This is why using a string with 'private_key_bits' will result in unexpected behavior.

Further inspection of the earlier initialization in the same function:

    SET_OPTIONAL_STRING_ARG("config", req->config_filename, default_ssl_conf_filename);
    SET_OPTIONAL_STRING_ARG("config_section_name", req->section_name, "req");
    req->global_config = CONF_load(NULL, default_ssl_conf_filename, NULL);
    req->req_config = CONF_load(NULL, req->config_filename, NULL);

    if (req->req_config == NULL) {
        return FAILURE;
    }

And elsewhere in another function:

    /* default to 'openssl.cnf' if no environment variable is set */
    if (config_filename == NULL) {
        snprintf(default_ssl_conf_filename, sizeof(default_ssl_conf_filename), "%s/%s",
                X509_get_default_cert_area(),
                "openssl.cnf");
    } else {
        strlcpy(default_ssl_conf_filename, config_filename, sizeof(default_ssl_conf_filename));
    }

Reveals that 'config' in $configargs is an override for any default setting elsewhere.  This actually negates the comment in the documentation that says "Note: You need to have a valid openssl.cnf installed for this function to operate correctly. See the notes under the installation section for more information."  A more correct sentence would be "Note:  You need to either have a valid openssl.cnf set up or use $configargs to point at a valid openssl.cnf file for this function to operate correctly."

All of that goes to show that looking at the PHP source code is the only real way to figure out what is actually happening.  Doing so saves time and effort.

down

Anonymous ¶

9 years ago

For those of you using Debian-based systems, the openssl configuration file is at: /etc/ssl/openssl.cnf

down

main ATT jokester DOTT fr ¶

16 years ago

To set the "basicConstraints" to  "critical,CA:TRUE", you have to define configargs, but in the openssl_csr_sign() function !

That's my example of code to sign a "child" certificate :

$CAcrt = "file://ca.crt";
$CAkey = array("file://ca.key", "myPassWord");

$clientKeys = openssl_pkey_new();
$dn = array(
    "countryName" => "FR",
    "stateOrProvinceName" => "Finistere",
    "localityName" => "Plouzane",
    "organizationName" => "Ecole Nationale d'Ingenieurs de Brest",
    "organizationalUnitName" => "Enib Students",
    "commonName" => "www.enib.fr",
    "emailAddress" => "ilovessl@php.net"
);
$csr = openssl_csr_new($dn, $clientPrivKey);

$configArgs = array("x509_extensions" => "v3_req");
$cert = openssl_csr_sign($csr, $CAcrt, $CAkey, 100, $configArgs);

openssl_x509_export_to_file($cert, "childCert.crt");

Then if you want to add some more options, you can edit the "/etc/ssl/openssl.cnf" ssl config' file (debian path), and add these after the [ v3_req ] tag.

down

alex at nodex dot co dot uk ¶

10 years ago

In the PHP example above it uses "UK" as the country name which is incorrect, the country name must be "GB"

down

Richard Lynch ¶

11 years ago

There appears to be no openssl_csr_free function.

At least not here.

If it's in the source, one might be able to just call it.

If it's not in the source, it probably should be.

down

Anonymous ¶

19 years ago

If you get the error:

error:0D11A086:asn1 encoding routines:ASN1_mbstring_copy:string too short

then look at your key:value pairs in the $dn (distinguished name) array.

If you have one value (like "organizationalUnitName" = "") set to an empty string, it will throw the above error.

Fix the error by either eliminating that array element from $dn completely, or using a space " " instead of an empty string.

down

robertliu AT wiscore DOT com ¶

19 years ago

I am using PHP-4.3.11.
The type of configargs--private_key_bits is a INTEGER, not a string.
An example of configration:
<?php
$config = array(
  "digest_alg" => "sha1",
  "private_key_bits" => 2048,
  "private_key_type" => OPENSSL_KEYTYPE_DSA,
  "encrypt_key" => false
);
?>

down

-1

dankybastard at hotmail ¶

19 years ago

As you probably guessed from the example, the documentation is misinforming.  openssl_csr_new returns a CSR resource or FALSE on failure.

mixed openssl_csr_new (assoc_array dn, resource_privkey, [...])

down

-1

@operator ¶

8 years ago

One command to create modern certificate request with 4 SAN subdomain.
According to RFC you can change CN (common name) and subjectAltName. When cert validated searching in CN and subjectAltName.

openssl req -new -nodes -config <( cat <<-EOF
[req]
default_bits = 2048
prompt = no
default_md = sha256
req_extensions = re
distinguished_name = dn
[ dn ]
CN = my.tld
C = country
ST = state
L = location
O = ORGANISATION
[ re ]
subjectAltName = DNS.1: www.my.tld, DNS.2: www2.my.tld, DNS.3: www3.my.tld, DNS.4: www4.my.tld
EOF
) -keyout secret.key -out req.csr

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openssl_csr_new

Description

Parameters

Return Values

Changelog

Examples

See Also

Found A Problem?

User Contributed Notes 10 notes