sha1 Calculate the sha1 hash of a string stringsha1 stringstr boolraw_output Calculates the sha1 hash of str using the US Secure Hash Algorithm 1, and returns that hash. The hash is a 40-character hexadecimal number. If the optional raw_output is set to &true;, then the sha1 digest is instead returned in raw binary format with a length of 20. The optional raw_output parameter was added in PHP 5.0.0 and defaults to &false; See also sha1_file, crc32, and md5