SHA-1 or SHA1 is a one-way hash function;
it computes a 160-bit message digest.
SHA-1 often appears in security protocols; for example,
many HTTPS websites use RSA with SHA-1 to secure their connections.
BitTorrent uses SHA-1 to verify downloads.
Git and Mercurial use SHA-1 digests to identify commits.

A US government standard, FIPS 180-1, defines SHA-1.

Find the SHA-1 message digest for a string of octets. You may either call a SHA-1 library, or implement SHA-1 in your language. Both approaches interest Rosetta Code.



 Warning: SHA-1 has known weaknesses. Theoretical attacks may find a collision after 252 operations, or perhaps fewer.
This is much faster than a brute force attack of 280 operations. USgovernment deprecated SHA-1.
For production-grade cryptography, users may consider a stronger alternative, such as SHA-256 (from the SHA-2 family) or the upcoming SHA-3.


 
program Sha_1;
 
{$APPTYPE CONSOLE}
 
uses
  System.SysUtils,
  DCPsha1;
 
function SHA1(const Str: string): string;
var
  HashDigest: array of byte;
  d: Byte;
begin
  Result := '';
  with TDCP_sha1.Create(nil) do
  begin
    Init;
    UpdateStr(Str);
    SetLength(HashDigest, GetHashSize div 8);
    final(HashDigest[0]);
    for d in HashDigest do
      Result := Result + d.ToHexString(2);
    Free;
  end;
end;
 
begin
  Writeln(SHA1('Rosetta Code'));
  readln;
end.