Encrypt.php

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<?php

namespace Rsi\Fred;

/**
 *  Encryption (and decryption) component.
 */
class Encrypt extends Component{

  protected $_key = null; //!< Master key (used for padding).
  protected $_keyFile = null; //!< File where master key is stored. If the file does not exist, a key is generated and saved.
  protected $_method = 'AES-256-CTR'; //!< Encryption method (see openssl_get_cipher_methods()).
  protected $_blockSize = 32000; //!< File encryption block size.

  /**
   * Generate an encryption key.
   * @param string $key  Custom/user key.
   * @return string  Generated key based on custom/user key and master key (binary).
   */
  protected function key($key){
    return sha1($key . $this->key,true) . $key . $this->key;
  }
  /**
   * Generate an initialization vector.
   * @param int $length  Length of the initialization vector.
   * @return string  Generated initialization vector (binary).
   */
  protected function initVector(&$length = null){
    $iv = openssl_random_pseudo_bytes($length = openssl_cipher_iv_length($this->_method),$strong);
    if(!$strong) $this->component('log')->warning("Generated initialization vector for method '{$this->_method}' not cryptographically strong",__FILE__,__LINE__);
    return $iv;
  }
  /**
   * Encrypt a string.
   * @param string $str  Input string.
   * @param string $key  Key for encryption.
   * @return string  Encrypted data (binary). This includes the used method, so this can be safely changed.
   */
  public function str($str,$key = null){
    $iv = $this->initVector();
    return $this->_method . ':' . $iv . openssl_encrypt($str,$this->_method,$this->key($key),OPENSSL_RAW_DATA,$iv);
  }
  /**
   * Decrypt an encrypted string.
   * @param string $data  String encrypted with str().
   * @param string $key  Key for decryption (same one as used with encryption).
   * @return string  Decrypted string.
   */
  public function decrypt($data,$key = null){
    $length = openssl_cipher_iv_length($method = substr($data,0,$i = strpos($data,':')));
    return openssl_decrypt(substr($data,$i + 1 + $length),$method,$this->key($key),OPENSSL_RAW_DATA,substr($data,$i + 1,$length));
  }
  /**
   * Encrypt a file.
   * @param string $source  Original file.
   * @param string $target  File to write encrypted data to. This includes the used method and block size, so these can be
   *   safely changed.
   * @param string $key  Key for encryption.
   * @return int  Number of bytes written.
   */
  public function file($source,$target,$key = null){
    $key = $this->key($key);
    $source = fopen($source,'r');
    $target = fopen($target,'w');
    $config = $this->_method . ':' . $this->_blockSize;
    $result = fwrite($target,pack('n',strlen($config)) . $config . ($iv = $this->initVector($length)));
    while(!feof($source)){
      $result += fwrite($target,$data = openssl_encrypt(fread($source,$this->_blockSize),$this->_method,$key,OPENSSL_RAW_DATA,$iv));
      $iv = substr($data,0,$length);
    }
    fclose($source);
    fclose($target);
    return $result;
  }
  /**
   * Decrypt an encrypted file.
   * @param string $source  File encrypted with file().
   * @param string $target  File to write decrypted data to.
   * @param string $key  Key for decryption (same one as used with encryption).
   * @return int  Number of bytes written.
   */
  public function decryptFile($source,$target,$key = null){
    $key = $this->key($key);
    $source = fopen($source,'r');
    $target = fopen($target,'w');
    list($method,$size) = explode(':',fread($source,unpack('n',fread($source,2))[1]));
    $iv = fread($source,$length = openssl_cipher_iv_length($method));
    $result = 0;
    while(!feof($source)){
      $result += fwrite($target,openssl_decrypt($data = fread($source,$size),$method,$key,OPENSSL_RAW_DATA,$iv));
      $iv = substr($data,0,$length);
    }
    fclose($source);
    fclose($target);
    return $result;
  }

  protected function getKey(){
    if(!$this->_key && !($this->_key = $this->config('key'))){
      if(!$this->_keyFile) throw new Exception('No master key (file)');
      if(is_file($this->_keyFile)) $this->_key = file_get_contents($this->_keyFile);
      else{
        \Rsi\File::write($this->_keyFile,$this->_key = \Rsi\Str::random(256),0444);
        $this->component('log')->warning('Generated an encryption master key',__FILE__,__LINE__,['key' => $this->_key]);
      }
    }
    return $this->_key;
  }

}