make_file_url_s3_php

<?php

class FileReadURL{
  function getUrl(){
    $aws_access_key_id = '[読み取り用のAWSキー]';
    $aws_secret_key = '[読み取り用のAWSシークレットキー]';
    $aws_bucket = 'バケット名';
    $downloadAudioTimeout = '作成したURLの有効時間';
    $file_path = '[ディレクトリパス]/[ファイル名]';
     
    $http_verb = "GET";
    $content_md5 = "";
    $content_type = "";
    $expires = strtotime($downloadAudioTimeout);
    $canonicalizedAmzHeaders = "";
    $canonicalizedResource = '/' . $aws_bucket . '/' . $file_path;
     
    $stringToSign = $http_verb . "\n" . $content_md5 . "\n" . $content_type . "\n" . $expires . "\n" . $canonicalizedAmzHeaders . $canonicalizedResource;       
                      
    $signature = urlencode($this->hex2b64($this->hmacsha1($aws_secret_key, utf8_encode($stringToSign))));
        
    $url = "https://$aws_bucket.s3.amazonaws.com/$file_path?AWSAccessKeyId=$aws_access_key_id&Signature=$signature&Expires=$expires";
    
    return $url;
  }

  private function hmacsha1($key,$data) 
  {
    $blocksize=64;
    $hashfunc='sha1';
    if (strlen($key)>$blocksize)
        $key=pack('H*', $hashfunc($key));
    $key=str_pad($key,$blocksize,chr(0x00));
    $ipad=str_repeat(chr(0x36),$blocksize);
    $opad=str_repeat(chr(0x5c),$blocksize);
    $hmac = pack(
                'H*',$hashfunc(
                    ($key^$opad).pack(
                        'H*',$hashfunc(
                            ($key^$ipad).$data
 
                        )
                    )
                )
            );
    return bin2hex($hmac);
  }
 
  /*
   * Used to encode a field for Amazon Auth
   * (taken from the Amazon S3 PHP example library)
   */
  private function hex2b64($str)
  {
      $raw = '';
      for ($i=0; $i < strlen($str); $i+=2)
      {
          $raw .= chr(hexdec(substr($str, $i, 2)));
      }
      return base64_encode($raw);
  }
}

  $obj = new FileReadURL();
  echo $obj->getUrl();