sha1_file()

(PHP 4 >= 4.3.0, PHP 5, PHP 7)

计算文件的 sha1 散列值

说明

利用»美国安全散列算法 1，计算并返回由$filename指定的文件的 sha1 散列值。该散列值是一个 40 字符长度的十六进制数字。

参数

要散列的文件的文件名。

如果被设置为TRUE，sha1 摘要将以 20 字符长度的原始格式返回。

返回值

成功返回一个字符串，否则返回FALSE。

范例

Example #1sha1_file()范例

更新日志

参见

• sha1()计算字符串的 sha1 散列值
• md5_file()计算指定文件的 MD5 散列值
• crc32()计算一个字符串的 crc32 多项式

Just for the record - 
As some have pointed out, you have two ways to generate the hash of a file:
Method 1 [this function]: sha1_file($file)
Method 2: sha1(file_get_contents($file))
It's important to realize that these two methods are NOT the same thing. If they were, I seriously doubt this function would exist.
The key difference, as far as I can tell, is how the file's contents are loaded. The second method loads the entirety of $file into memory before passing it to sha1($str). Method two, however, loads the contents of $file as they are needed to create the hash.
If you can guarantee that you'll only ever have to hash relatively small files, this difference means very little. If you have larger ones, though, loading the entirety of file into memory is a bad idea: best case, you slow down your server as it tries to handle the request; worse case, you run out of memory and don't get your hash at all.
Just try to keep this in mind if you decide to load the file's contents yourself, in lieu of using this function. On my system, I was able to use this function to generate the hash of a 2.6GB file in 22 seconds, whereas I could not with the second method, due to an out-of-memory error (which took 185 seconds).

P2P programs like LimeWire utilize sha1 to identify files. However they do it in base32. Here's an utility class if you want to write a Gnutella client in PHP5
/**
Utility base32 SHA1 class for PHP5
Copyright (C) 2006 Karl Magdsick (original author for Python)
          Angel Leon (ported to PHP5)
          Lime Wire LLC
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
class SHA1 {
 static $BASE32_ALPHABET = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';
 /** Given a file it creates a magnetmix */
 static function fileSHA1($file) {
  $raw = sha1_file($file,true);
  return SHA1::base32encode($raw);
 } //fileSHA1
 /** Takes raw input and converts it to base32 */
 static function base32encode($input) {
  $output = '';
  $position = 0;
  $storedData = 0;
  $storedBitCount = 0;
  $index = 0;
  while ($index  $storedBitCount];
    $storedData &= ((1  0) {
   $storedData 

鹏仔微信 15129739599 鹏仔QQ344225443 鹏仔前端 pjxi.com 共享博客 sharedbk.com