Generate signature

# openssl_sign

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

openssl_sign — Generate signature

### 说明

function openssl_sign(
string `$data`,
string `&$signature`,
#[\SensitiveParameter]OpenSSLAsymmetricKey|OpenSSLCertificate|array|string `$private_key`,
string|int `$algorithm` = `OPENSSL_ALGO_SHA1`,
int `$padding` = 0
): bool

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.

### 参数

`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".

`padding`
  RSA PSS padding to use.

### 返回值

成功时返回 `true`， 或者在失败时返回 `false`。

### 更新日志

版本 | 说明
--- | ---
8.5.0 | The optional parameter `padding` has been added.
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.

### 示例

示例 #1 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);
    ?>

示例 #2 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);
    ?>

### 参见

- openssl_verify() - 验证签名

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