暗号化ライブラリをMcryptからOpenSSLにアップグレードする

Question

以下の一般的に参照されるライブラリを暗号化に使用しています。非推奨のライブラリを使用しないように、McryptからOpenSSLにアップグレードしたいと考えています。

これが可能かどうかを調べています。私はこれについていくつかの調査を行いましたが、矛盾する情報を見つけました：

この投稿によると、Mcryptで暗号化されたOpenSSLを使用してデータを復号化することは不可能です。 https://stackoverflow.com/a/19748494/5834657

ただし、この投稿では、パディングを使用することが可能であると述べています。私の関数はパディングを使用しているようです。これは、これを機能させるために必要な適切なタイプのパディングですか？ https://stackoverflow.com/a/31614770/5834657

<?php 

namespace Utilities\Encryption;

/**
* A class to handle secure encryption and decryption of arbitrary data
*
* Note that this is not just straight encryption.  It also has a few other
* features in it to make the encrypted data far more secure.  Note that any
* other implementations used to decrypt data will have to do the same exact
*  operations.  
*
* Security Benefits:
*
* - Uses Key stretching
* - Hides the Initialization Vector
* - Does HMAC verification of source data
*
*/

class Encryption {

/**
 * @var string $cipher The mcrypt cipher to use for this instance
 */
protected $cipher = '';

/**
 * @var int $mode The mcrypt cipher mode to use
 */
protected $mode = '';

/**
 * @var int $rounds The number of rounds to feed into PBKDF2 for key generation
 */
protected $rounds = 100;

/**
 * Constructor!
 *
 * @param string $cipher The MCRYPT_* cypher to use for this instance
 * @param int    $mode   The MCRYPT_MODE_* mode to use for this instance
 * @param int    $rounds The number of PBKDF2 rounds to do on the key
 */
public function __construct($cipher, $mode, $rounds = 100) {
    $this->cipher = $cipher;
    $this->mode = $mode;
    $this->rounds = (int) $rounds;
}

/**
 * Decrypt the data with the provided key
 *
 * @param string $data The encrypted datat to decrypt
 * @param string $key  The key to use for decryption
 * 
 * @returns string|false The returned string if decryption is successful
 *                           false if it is not
 */
public function decrypt($data, $key) {
    $salt = substr($data, 0, 128);
    $enc = substr($data, 128, -64);
    $mac = substr($data, -64);

    list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key);

    if ($mac !== hash_hmac('sha512', $enc, $macKey, true)) {
         return false;
    }

    $dec = mcrypt_decrypt($this->cipher, $cipherKey, $enc, $this->mode, $iv);

    $data = $this->unpad($dec);

    return $data;
}

/**
 * Encrypt the supplied data using the supplied key
 * 
 * @param string $data The data to encrypt
 * @param string $key  The key to encrypt with
 *
 * @returns string The encrypted data
 */
public function encrypt($data, $key) {
    $salt = mcrypt_create_iv(128, MCRYPT_DEV_URANDOM);
    list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key);

    $data = $this->pad($data);

    $enc = mcrypt_encrypt($this->cipher, $cipherKey, $data, $this->mode, $iv);

    $mac = hash_hmac('sha512', $enc, $macKey, true);
    return $salt . $enc . $mac;
}

/**
 * Generates a set of keys given a random salt and a master key
 *
 * @param string $salt A random string to change the keys each encryption
 * @param string $key  The supplied key to encrypt with
 *
 * @returns array An array of keys (a cipher key, a mac key, and a IV)
 */
protected function getKeys($salt, $key) {
    $ivSize = mcrypt_get_iv_size($this->cipher, $this->mode);
    $keySize = mcrypt_get_key_size($this->cipher, $this->mode);
    $length = 2 * $keySize + $ivSize;

    $key = $this->pbkdf2('sha512', $key, $salt, $this->rounds, $length);

    $cipherKey = substr($key, 0, $keySize);
    $macKey = substr($key, $keySize, $keySize);
    $iv = substr($key, 2 * $keySize);
    return array($cipherKey, $macKey, $iv);
}

/**
 * Stretch the key using the PBKDF2 algorithm
 *
 * @see http://en.wikipedia.org/wiki/PBKDF2
 *
 * @param string $algo   The algorithm to use
 * @param string $key    The key to stretch
 * @param string $salt   A random salt
 * @param int    $rounds The number of rounds to derive
 * @param int    $length The length of the output key
 *
 * @returns string The derived key.
 */
protected function pbkdf2($algo, $key, $salt, $rounds, $length) {
    $size   = strlen(hash($algo, '', true));
    $len    = ceil($length / $size);
    $result = '';
    for ($i = 1; $i <= $len; $i++) {
        $tmp = hash_hmac($algo, $salt . pack('N', $i), $key, true);
        $res = $tmp;
        for ($j = 1; $j < $rounds; $j++) {
             $tmp  = hash_hmac($algo, $tmp, $key, true);
             $res ^= $tmp;
        }
        $result .= $res;
    }
    return substr($result, 0, $length);
}

protected function pad($data) {
    $length = mcrypt_get_block_size($this->cipher, $this->mode);
    $padAmount = $length - strlen($data) % $length;
    if ($padAmount == 0) {
        $padAmount = $length;
    }
    return $data . str_repeat(chr($padAmount), $padAmount);
}

protected function unpad($data) {
    $length = mcrypt_get_block_size($this->cipher, $this->mode);
    $last = ord($data[strlen($data) - 1]);
    if ($last > $length) return false;
    if (substr($data, -1 * $last) !== str_repeat(chr($last), $last)) {
        return false;
    }
    return substr($data, 0, -1 * $last);
 }
}

---

更新：ライブラリをOpenSSLに変換することにより、OpenSSLを使用してMcryptで暗号化された文字列を復号化しようとしています。

次に、上記のコードを使用してキーを使用して文字列を暗号化し、以下のコードと同じキーを使用してその値を復号化しようとしています。ただし、空の応答が返ってくるだけです。コメントアウトした場合：

$ data = $ this-> unpad（$ dec）

復号化関数では文字列を取得しますが、文字が乱雑になっています（最初に暗号化されたときのように見えます）。

<?php 

namespace Utilities\Encryption;

/**
* A class to handle secure encryption and decryption of arbitrary data
*
* Note that this is not just straight encryption.  It also has a few other
*  features in it to make the encrypted data far more secure.  Note that any
*  other implementations used to decrypt data will have to do the same exact
*  operations.  
*
* Security Benefits:
*
* - Uses Key stretching
* - Hides the Initialization Vector
* - Does HMAC verification of source data
*
*/
class EncryptionOpenSsl {

/**
 * @var string $cipher The mcrypt cipher to use for this instance
 */
protected $cipher = '';

/**
 * @var int $mode The mcrypt cipher mode to use
 */
protected $mode = '';

/**
 * @var int $rounds The number of rounds to feed into PBKDF2 for key generation
 */
protected $rounds = 100;

/**
 * Constructor!
 *
 * @param string $cipher The MCRYPT_* cypher to use for this instance
 * @param int    $mode   The MCRYPT_MODE_* mode to use for this instance
 * @param int    $rounds The number of PBKDF2 rounds to do on the key
 */
public function __construct($cipher, $rounds = 100) {
    $this->cipher = $cipher;
    // $this->mode = MCRYPT_MODE_CBC;
    $this->rounds = (int) $rounds;
}

/**
 * Decrypt the data with the provided key
 *
 * @param string $data The encrypted datat to decrypt
 * @param string $key  The key to use for decryption
 * 
 * @returns string|false The returned string if decryption is successful
 *                           false if it is not
 */
public function decrypt($data, $key) {
    $salt = substr($data, 0, 128);
    $enc = substr($data, 128, -64);
    $mac = substr($data, -64);

    list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key);

    if ($mac !== hash_hmac('sha512', $enc, $macKey, true)) {
         return false;
    }
    $dec = openssl_decrypt($enc, $this->cipher, $key, OPENSSL_RAW_DATA, $iv);
    // $dec = mcrypt_decrypt($this->cipher, $cipherKey, $enc, $this->mode, $iv);

    $data = $this->unpad($dec);

    return $data;
}

/**
 * Encrypt the supplied data using the supplied key
 * 
 * @param string $data The data to encrypt
 * @param string $key  The key to encrypt with
 *
 * @returns string The encrypted data
 */
public function encrypt($data, $key) {
    $salt = mcrypt_create_iv(128, MCRYPT_DEV_URANDOM);
    list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key);

    $data = $this->pad($data);

    $enc = mcrypt_encrypt($this->cipher, $cipherKey, $data, $this->mode, $iv);

    $mac = hash_hmac('sha512', $enc, $macKey, true);
    return $salt . $enc . $mac;
}

/**
 * Generates a set of keys given a random salt and a master key
 *
 * @param string $salt A random string to change the keys each encryption
 * @param string $key  The supplied key to encrypt with
 *
 * @returns array An array of keys (a cipher key, a mac key, and a IV)
 */
protected function getKeys($salt, $key) {
    $ivSize = mcrypt_get_iv_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);
    $keySize = mcrypt_get_key_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);
    $length = 2 * $keySize + $ivSize;

    $key = $this->pbkdf2('sha512', $key, $salt, $this->rounds, $length);

    $cipherKey = substr($key, 0, $keySize);
    $macKey = substr($key, $keySize, $keySize);
    $iv = substr($key, 2 * $keySize);
    return array($cipherKey, $macKey, $iv);
}

/**
 * Stretch the key using the PBKDF2 algorithm
 *
 * @see http://en.wikipedia.org/wiki/PBKDF2
 *
 * @param string $algo   The algorithm to use
 * @param string $key    The key to stretch
 * @param string $salt   A random salt
 * @param int    $rounds The number of rounds to derive
 * @param int    $length The length of the output key
 *
 * @returns string The derived key.
 */
protected function pbkdf2($algo, $key, $salt, $rounds, $length) {
    $size   = strlen(hash($algo, '', true));
    $len    = ceil($length / $size);
    $result = '';
    for ($i = 1; $i <= $len; $i++) {
        $tmp = hash_hmac($algo, $salt . pack('N', $i), $key, true);
        $res = $tmp;
        for ($j = 1; $j < $rounds; $j++) {
             $tmp  = hash_hmac($algo, $tmp, $key, true);
             $res ^= $tmp;
        }
        $result .= $res;
    }
    return substr($result, 0, $length);
}

protected function pad($data) {
    $length = mcrypt_get_block_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);
    $padAmount = $length - strlen($data) % $length;
    if ($padAmount == 0) {
        $padAmount = $length;
    }
    return $data . str_repeat(chr($padAmount), $padAmount);
}

protected function unpad($data) {
    $length = mcrypt_get_block_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);
    $last = ord($data[strlen($data) - 1]);
    if ($last > $length) return false;
    if (substr($data, -1 * $last) !== str_repeat(chr($last), $last)) {
        return false;
    }
    return substr($data, 0, -1 * $last);
 }
}

Answer 1

あなたの解読ルーチンのこのコードは私にとってはうまくいきます：

public function decrypt($data, $key) {
    $salt = substr($data, 0, 128);
    $enc = substr($data, 128, -64);
    $mac = substr($data, -64);

    list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key);

    if ($mac !== hash_hmac('sha512', $enc, $macKey, true)) {
         return false;
    }

    $dec = openssl_decrypt($enc, $this->cipher, $cipherKey, OPENSSL_RAW_DATA, $iv);

    return $dec;
}

テスト：

$keys = [
    'this is a secret key.',
    'G906m70p(IhzA5T&5x7(w0%a631)u)%D6E79cIYJQ!iP2U(xT13q6)tJ6gZ3D2wi&0")7cP5',
    chr(6) . chr(200) . chr(16) . 'my key ' . chr(3) . chr(4) . chr(192) . chr(254) . ' zyx0987!!',
    'and finally one more key to test with here:',
];


$data = [
    'A',
    'This is a test',
    'now test encrypting something a little bit longer with 1234567890.',
    '$length = mcrypt_get_block_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC); $last = ord($data[strlen($data) - 1]);',
    'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec sit amet pharetra urna. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Ut fringilla, quam sed eleifend eleifend, justo turpis consectetur tellus, quis tristique eros erat at nibh. Nunc dictum neque vel diam molestie fermentum. Pellentesque dignissim dui quis tortor eleifend, ut maximus elit egestas. Donec posuere odio et auctor porta. Quisque placerat condimentum maximus. Curabitur luctus dolor eget sem luctus, in dignissim tortor venenatis. Mauris eget nulla nisl.',
];

$failures = 0;

foreach ($data as $datum) {
    foreach ($keys as $key) {
        $enc = new Encryption(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);

        $encrypted = $enc->encrypt($datum, $key);

        $dec = new EncryptionOpenSsl('bf-cbc');

        $decrypted = $dec->decrypt($encrypted, $key);

        if (strcmp($datum, $decrypted) !== 0) {
            echo "Encryption with key '$key' of '$datum' failed.  '$decrypted' != '$datum'<br><br>\n\n";
            $failures++;
        }
    }
}

if ($failures) {
    echo "$failures tests failed.<br>\n";
} else {
    echo "ALL OKAY<br>\n";
}

あなたがそれがあなたのためにうまくいくことを確認できれば、私は答えを片付け、最終的な作業コードを追加できます。