PHP Str::substr方法代码示例

 /**
  * PKCS #7 unpadding function.
  * 
  * @param string $input Padded string to unpad
  * 
  * @return string
  */
 public static function unpad($input)
 {
     // Determine the padding size by converting the final byte of the
     // input to its decimal value
     $padsize = \ord(Str::substr($input, -1));
     // Return string minus the padding amount
     return Str::substr($input, 0, Str::strlen($input) - $padsize);
 }

 /**
  * This will normalize a hash to a certain length by extending it if
  * too short and truncating it if too long. This ensures that any
  * hash algo will work with any combination of other settings. However,
  * it is probably best to make sure that the keysize and algo size
  * are identical so that the input hash passes through unchanged.
  *
  * @param string $hash Hash to be normalized
  * @param int    $size Size of the desired output hash, in bytes
  * @param string $algo Hashing algorithm to use for internal operations
  *
  * @return string
  */
 private static function hashNormalize($hash, $size, $algo)
 {
     // Extend hash if too short
     while (Str::strlen($hash) < $size) {
         $hash .= \hash($algo, $hash, true);
     }
     // Truncate to specified number of bytes (if needed) and return
     return Str::substr($hash, 0, $size);
 }

 /**
  * Decrypt cyphertext
  * 
  * @param string $cyphertext Cyphertext to decrypt
  * @param string $password   Password that should be used to decrypt input data
  * @param int    $cost       Number of HMAC iterations to perform on key
  * 
  * @return string
  */
 public static function decrypt($cyphertext, $password, $cost = 0)
 {
     // Find the IV at the beginning of the cypher text
     $iv = Str::substr($cyphertext, 0, self::IVSIZE);
     // Gather the checksum portion of the cypher text
     $chksum = Str::substr($cyphertext, self::IVSIZE, self::CKSIZE);
     // Gather message portion of cyphertext after iv and checksum
     $message = Str::substr($cyphertext, self::IVSIZE + self::CKSIZE);
     // Derive key from password
     $key = self::key($password, $iv, $cost, self::RIJNDA, self::mode());
     // Calculate verification checksum
     $verify = self::checksum($message, $iv, $key, self::RIJNDA, self::mode());
     // Verify HMAC before decrypting
     self::checksumVerify($verify, $chksum);
     // Decrypt message and return
     return \openssl_decrypt($message, static::CIPHER, $key, 1, $iv);
 }

 /**
  * Decrypt cyphertext
  * 
  * @param string $cyphertext Cypher text to decrypt
  * @param string $password   Password that should be used to decrypt input data
  * @param int    $cost       Number of HMAC iterations to perform on key
  * @param string $cipher     Mcrypt cipher
  * @param string $mode       Mcrypt mode
  * @param string $algo       Hashing algorithm to use for internal operations
  * 
  * @return string|boolean Returns false on checksum validation failure
  */
 public static function decrypt($cyphertext, $password, $cost = 0, $cipher = MCRYPT_RIJNDAEL_128, $mode = MCRYPT_MODE_CBC, $algo = 'sha256')
 {
     // Determine that size of the IV in bytes
     $ivsize = \mcrypt_get_iv_size($cipher, $mode);
     // Find the IV at the beginning of the cypher text
     $iv = Str::substr($cyphertext, 0, $ivsize);
     // Gather the checksum portion of the cypher text
     $chksum = Str::substr($cyphertext, $ivsize, Str::hashSize($algo));
     // Gather message portion of cyphertext after iv and checksum
     $message = Str::substr($cyphertext, $ivsize + Str::hashSize($algo));
     // Derive key from password
     $key = self::key($password, $iv, $cost, $cipher, $mode, $algo);
     // Calculate verification checksum
     $verify = self::checksum($message, $iv, $key, $cipher, $mode, $algo);
     // If checksum could not be verified return false
     self::checksumVerify($verify, $chksum);
     // Decrypt unpad return
     return Pkcs7::unpad(\mcrypt_decrypt($cipher, $key, $message, $mode, $iv));
 }

 /**
  * Check the validity of a hash.
  * 
  * @param string $input    Input to test.
  * @param string $hash     Known hash to validate against.
  * @param string $password HMAC password to use during iterative hash. 
  * 
  * @return boolean
  */
 public static function verify($input, $hash, $password)
 {
     // Get the salt value from the decrypted prefix
     $salt = Str::substr($hash, 0, 16);
     // Get the encrypted cost bytes
     $cost = self::bin2dec(Otp::crypt(Str::substr($hash, 28, 4), $password));
     // Get the entire cost+hash blob for comparison
     $blob = Str::substr($hash, 16, 16);
     if (!Str::equal(self::costHash($cost, $salt, $password), $blob)) {
         return false;
     }
     // Return the boolean equivalence
     return Str::equal($hash, self::build($input, $password, $cost, $salt));
 }