PHP Unconference Europe 2015

openssl_sign

(PHP 4 >= 4.0.4, PHP 5)

openssl_sign署名を生成する

説明

bool openssl_sign ( string $data , string &$signature , mixed $priv_key_id [, mixed $signature_alg = OPENSSL_ALGO_SHA1 ] )

openssl_sign() は、指定した data の署名を作ります。 priv_key_id で指定した秘密鍵を使用して、暗号のデジタル署名を生成します。 data 自体は暗号化されないことに注意してください。

パラメータ

data

署名したいデータの文字列。

signature

成功した場合、署名が signature に格納されます。

priv_key_id

resource - openssl_get_privatekey() が返す鍵。

string - PEM フォーマットの鍵。

signature_alg

int - いずれかの 署名アルゴリズム

string - openssl_get_md_methods() が返す文字列 ("sha256WithRSAEncryption" や "sha384" など)。

返り値

成功した場合に TRUE を、失敗した場合に FALSE を返します。

例1 openssl_sign() の例

<?php
// $data に署名するデータが含まれていると仮定

// ファイルから秘密鍵を取得して準備
$pkeyid openssl_pkey_get_private("file://src/openssl-0.9.6/demos/sign/key.pem");

// 署名を計算
openssl_sign($data$signature$pkeyid);

// メモリからキーを開放する
openssl_free_key($pkeyid);
?>

例2 openssl_sign() の例

<?php
// 署名したいデータ
$data 'my data';

// 新しい秘密鍵と公開鍵を作成
$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'];

// 署名を作成
openssl_sign($data$signature$private_key_pemOPENSSL_ALGO_SHA256);

// それらを保存
file_put_contents('private_key.pem'$private_key_pem);
file_put_contents('public_key.pem'$public_key_pem);
file_put_contents('signature.dat'$signature);

// 署名を検証
$r openssl_verify($data$signature$public_key_pem"sha256WithRSAEncryption");
var_dump($r);
?>

参考

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User Contributed Notes 3 notes

up
2
adam dot mansfeld at gmail dot com
9 years ago
Hello,

the fourth parameter 'signature_alg' to choose the signature algorithm can be one of:

OPENSSL_ALGO_SHA1
OPENSSL_ALGO_MD5
OPENSSL_ALGO_MD4
OPENSSL_ALGO_MD2

Just for the case that somebody needs this.

Regards
up
1
Chris Kistner
4 years ago
The list of Signature Algorithms (constants) is very limited! Fortunately the newer versions of php/openssl allow you to specify the signature algorithm as a string.

You can use the 'openssl_get_md_methods' method to get a list of digest methods. Only some of them may be used to sign with RSA private keys.

Those that can be used to sign with RSA private keys are: md4, md5, ripemd160, sha, sha1, sha224, sha256, sha384, sha512

Here's the modified Example #1 with SHA-512 hash:
<?php
// $data is assumed to contain the data to be signed

// fetch private key from file and ready it
$fp = fopen("/src/openssl-0.9.6/demos/sign/key.pem", "r");
$priv_key = fread($fp, 8192);
fclose($fp);
$pkeyid = openssl_get_privatekey($priv_key);

// compute signature with SHA-512
openssl_sign($data, $signature, $pkeyid, "sha512");

// free the key from memory
openssl_free_key($pkeyid);
?>
up
1
edmarw at yahoo dot com
7 years ago
This may help if you just want a real-simple private/public key pair:

<?php

$data
= "Beeeeer is really good.. hic...";

// You can get a simple private/public key pair using:
// openssl genrsa 512 >private_key.txt
// openssl rsa -pubout <private_key.txt >public_key.txt

// IMPORTANT: The key pair below is provided for testing only.
// For security reasons you must get a new key pair
// for production use, obviously.

$private_key = <<<EOD
-----BEGIN RSA PRIVATE KEY-----
MIIBOgIBAAJBANDiE2+Xi/WnO+s120NiiJhNyIButVu6zxqlVzz0wy2j4kQVUC4Z
RZD80IY+4wIiX2YxKBZKGnd2TtPkcJ/ljkUCAwEAAQJAL151ZeMKHEU2c1qdRKS9
sTxCcc2pVwoAGVzRccNX16tfmCf8FjxuM3WmLdsPxYoHrwb1LFNxiNk1MXrxjH3R
6QIhAPB7edmcjH4bhMaJBztcbNE1VRCEi/bisAwiPPMq9/2nAiEA3lyc5+f6DEIJ
h1y6BWkdVULDSM+jpi1XiV/DevxuijMCIQCAEPGqHsF+4v7Jj+3HAgh9PU6otj2n
Y79nJtCYmvhoHwIgNDePaS4inApN7omp7WdXyhPZhBmulnGDYvEoGJN66d0CIHra
I2SvDkQ5CmrzkW5qPaE2oO7BSqAhRZxiYpZFb5CI
-----END RSA PRIVATE KEY-----
EOD;
$public_key = <<<EOD
-----BEGIN PUBLIC KEY-----
MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBANDiE2+Xi/WnO+s120NiiJhNyIButVu6
zxqlVzz0wy2j4kQVUC4ZRZD80IY+4wIiX2YxKBZKGnd2TtPkcJ/ljkUCAwEAAQ==
-----END PUBLIC KEY-----
EOD;

$binary_signature = "";

// At least with PHP 5.2.2 / OpenSSL 0.9.8b (Fedora 7)
// there seems to be no need to call openssl_get_privatekey or similar.
// Just pass the key as defined above
openssl_sign($data, $binary_signature, $private_key, OPENSSL_ALGO_SHA1);

// Check signature
$ok = openssl_verify($data, $binary_signature, $public_key, OPENSSL_ALGO_SHA1);
echo
"check #1: ";
if (
$ok == 1) {
    echo
"signature ok (as it should be)\n";
} elseif (
$ok == 0) {
    echo
"bad (there's something wrong)\n";
} else {
    echo
"ugly, error checking signature\n";
}

$ok = openssl_verify('tampered'.$data, $binary_signature, $public_key, OPENSSL_ALGO_SHA1);
echo
"check #2: ";
if (
$ok == 1) {
    echo
"ERROR: Data has been tampered, but signature is still valid! Argh!\n";
} elseif (
$ok == 0) {
    echo
"bad signature (as it should be, since data has beent tampered)\n";
} else {
    echo
"ugly, error checking signature\n";
}

?>
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