DELPHI - How get hash value for file (SHA-1 fingerprint)

Hash function returns same value for same (in this case) file. This uses SHA-1 (Secure Hash Algorithm) algorithm.

uses IdHashMessageDigest;
...
var
  sFile : string;
  pSHA : TIdHashSHA1;
  pStream : TFileStream;
begin
  sFile := 'c:\_ax\error.png';

  pSHA := TIdHashSHA1.Create;
  pStream := TFileStream.Create( sFile, fmOpenRead or fmShareDenyWrite );

 try
   ShowMessage( 'File fingerprint = ' + pSHA.HashStreamAsHex( pStream ) );
 finally
   pStream.Free;
   pSHA.Free;
 end;

Output:

DELPHI - How get hash value for string (SHA-1 fingerprint)

Hash function returns same value for same string. This uses SHA-1 (Secure Hash Algorithm) algorithm.

uses IdHashSHA;
...
var
  pSHA : TIdHashSHA1;
begin
  pSHA := TIdHashSHA1.Create;

  try
    ShowMessage( 'abc = ' + pSHA.HashStringAsHex( 'abc' ) + #13 +
                 'abc = ' + pSHA.HashStringAsHex( 'abc' ) + #13 +
                 'abd = ' + pSHA.HashStringAsHex( 'abd' ) );
  finally
    pSHA.Free;
  end;

Output:

DELPHI - How get MD5 hash value for string (RSA-MD5 fingerprint)

Hash function returns same value for same string. This uses RSA-MD5 algorithm.

uses IdHashMessageDigest;
...
var
  pMD5: TIdHashMessageDigest5;
begin
  pMD5 := TIdHashMessageDigest5.Create;
  try
    ShowMessage( 'abc = ' + pMD5.HashStringAsHex( 'abc' ) + #13 +
                 'abc = ' + pMD5.HashStringAsHex( 'abc' ) + #13 +
                 'abd = ' + pMD5.HashStringAsHex( 'abd' ) );
  finally
    pMD5.Free;
  end;

Output: