openssl_sign

Generate signature

&reftitle.description; `bool` `openssl_sign` `string` `data` `string` `signature` #[\SensitiveParameter]``OpenSSLAsymmetricKey``OpenSSLCertificate``array``string```private_key` ``string``int```algorithm` `OPENSSL_ALGO_SHA1`

`openssl_sign` computes a signature for the specified `data` by generating a cryptographic digital signature using the private key associated with `private_key`. Note that the data itself is not encrypted.

&reftitle.parameters;

`data`

- The string of data you wish to sign

`signature`

- If the call was successful the signature is returned in `signature`.

`private_key`

- `OpenSSLAsymmetricKey` - a key, returned by `openssl_get_privatekey`

  `string` - a PEM formatted key

`algorithm`

- `int` - one of these Signature Algorithms.

  `string` - a valid string returned by `openssl_get_md_methods` example, "sha256WithRSAEncryption" or "sha384".

&reftitle.returnvalues;

&return.success;

&reftitle.changelog;

&Version; | &Description;
8.0.0 | `private_key` accepts an `OpenSSLAsymmetricKey` or `OpenSSLCertificate` instance now; previously, a &resource; of type `OpenSSL key` or `OpenSSL X.509` was accepted.

&reftitle.examples;

### `openssl_sign` example

    <?php
    // $data is assumed to contain the data to be signed

    // fetch private key from file and ready it
    $pkeyid = openssl_pkey_get_private("file://src/openssl-0.9.6/demos/sign/key.pem");

    // compute signature
    openssl_sign($data, $signature, $pkeyid);

    // free the key from memory
    openssl_free_key($pkeyid);
    ?>

### `openssl_sign` example

    <?php
    //data you want to sign
    $data = 'my data';

    //create new private and public key
    $new_key_pair = openssl_pkey_new(array(
        "private_key_bits" => 2048,
        "private_key_type" => OPENSSL_KEYTYPE_RSA,
    ));
    openssl_pkey_export($new_key_pair, $private_key_pem);

    $details = openssl_pkey_get_details($new_key_pair);
    $public_key_pem = $details['key'];

    //create signature
    openssl_sign($data, $signature, $private_key_pem, OPENSSL_ALGO_SHA256);

    //save for later
    file_put_contents('private_key.pem', $private_key_pem);
    file_put_contents('public_key.pem', $public_key_pem);
    file_put_contents('signature.dat', $signature);

    //verify signature
    $r = openssl_verify($data, $signature, $public_key_pem, "sha256WithRSAEncryption");
    var_dump($r);
    ?>

&reftitle.seealso;

- `openssl_verify`