uses System.IO, System.Security.Cryptography, System.Text;

type
hashtype = (MD5,SHA1,SHA256,SHA384,SHA512);

frmMain = class(System.Windows.Forms.Form)
procedure GroupCompare_CheckedChanged(sender: System.Object; e: System.EventArgs);
procedure btnFile_Click(sender: System.Object; e: System.EventArgs);
procedure btnCompare_Click(sender: System.Object; e: System.EventArgs);
private
procedure ClearForm;
function GetHash(contents: array of byte; hasht: hashtype): string;
function GetByteString(data: array of Byte): string;
public
function GetFileHash(const filename: string; hasht: hashtype): string;
function GetStringHash(const input: string; hasht: hashtype): string;
end;

procedure frmMain.ClearForm;
begin
txtValue1.Text := '';
txtValue2.Text := '';
txtResults1.Text := '';
txtResults2.Text := '';
end;

procedure frmMain.btnFile_Click(sender: System.Object; e: System.EventArgs);
begin
if ofdFiles.ShowDialog = System.Windows.Forms.DialogResult.OK then
begin
case Convert.ToInt32(Button(sender).Tag.ToString) of
0: txtValue1.Text:= ofdFiles.FileName;
1: txtValue2.Text:= ofdFiles.FileName;
end;
end;
end;

function frmMain.GetByteString(data: array of Byte): string;
var
sBuilder: StringBuilder;
i: integer;
begin
sBuilder:= StringBuilder.Create();
for i:= 0 to Length(data) - 1 do
begin
sBuilder.Append(data[i].ToString('x2'));
end;
result:= sBuilder.ToString();
end;

function frmMain.GetFileHash(const filename: string; hasht: hashtype): string;
var
oFileStream: System.IO.FileStream;
instance: FileInfo;
lBytes: System.Int64;
filecontents: array of byte;
begin
try
if (filename <> '') then
begin
instance:= FileInfo.Create(filename);
oFileStream:= instance.OpenRead;
lBytes:= oFileStream.Length;
SetLength(filecontents, lBytes);
oFileStream.Read(filecontents, 0, lBytes);
oFileStream.Close();
result:= GetHash(filecontents, hasht);
end
else
begin
result:= '';
end;
except on ex: Exception do
begin
MessageBox.Show(ex.Message, ex.Source, MessageBoxButtons.OK, MessageBoxIcon.Error);
result:= '';
end;
end;
end;

function frmMain.GetHash(contents: array of byte; hasht: hashtype): string;
var
res: array of Byte;
HashA: HashAlgorithm;
begin
Case hasht of
hashtype.MD5: begin
HashA:= MD5CryptoServiceProvider.Create;
res:= HashA.ComputeHash(contents)
end;
hashtype.SHA1: begin
HashA:= SHA1Managed.Create;
res:= HashA.ComputeHash(contents);
end;
hashtype.SHA256: begin
HashA:= SHA256Managed.Create;
res:= HashA.ComputeHash(contents);
end;
hashtype.SHA384: begin
HashA:= SHA384Managed.Create;
res:= HashA.ComputeHash(contents);
end;
hashtype.SHA512: begin
HashA:= SHA512Managed.Create;
res:= HashA.ComputeHash(contents);
end;
end;
result:= GetByteString(res);
end;

function frmMain.GetStringHash(const input: string; hasht: hashtype): string;
begin
result:= GetHash(Encoding.Default.GetBytes(input), hasht);
end;

procedure frmMain.btnCompare_Click(sender: System.Object; e: System.EventArgs);
var
myCursor: System.Windows.Forms.Cursor;
hasht: hashtype;
begin
myCursor:= Cursor;
Cursor:= Cursors.WaitCursor;
try
try
if radMD5.Checked then
hasht:= hashtype.MD5;
if radSHA1.Checked then
hasht:= hashtype.SHA1;
if radSHA256.Checked then
hasht:= hashtype.SHA256;
if radSHA384.Checked then
hasht:= hashtype.SHA384;
if radSHA512.Checked then
hasht:= hashtype.SHA512;

if radFiles.Checked then
begin
txtResults1.Text:= GetFileHash(txtValue1.Text, hasht);
txtResults2.Text:= GetFileHash(txtValue2.Text, hasht);
end
else
begin
txtResults1.Text:= GetStringHash(txtValue1.Text, hasht);
txtResults2.Text:= GetStringHash(txtValue2.Text, hasht);
end;

if (System.&String.Compare(txtResults1.Text, txtResults2.Text) = 0) then
begin
picResult.Image:= ImageList1.Images[1];
end
else
begin
picResult.Image:= ImageList1.Images[0];
end;

except
on ex: Exception do
MessageBox.Show(ex.Message, ex.Source, MessageBoxButtons.OK, MessageBoxIcon.Error);
end;
finally
Cursor:= myCursor;
end;
end;

procedure frmMain.GroupCompare_CheckedChanged(sender: System.Object; e: System.EventArgs);
var
i: System.Int32;
begin
ClearForm;
if sender is control then
begin
try
i:= Convert.ToInt32(Control(Sender).Tag.ToString);
except
i:= 0;
end;
end;

case i of
0: begin
lblValue1.Text:= 'File 1:';
lblValue2.Text:= 'File 2:';
txtValue1.ReadOnly:= True;
txtValue2.ReadOnly:= True;
btnValue1.Visible:= True;
btnValue2.Visible:= True;
end;
1: begin
lblValue1.Text:= 'String 1:';
lblValue2.Text:= 'String 2:';
txtValue1.ReadOnly:= False;
txtValue2.ReadOnly:= False;
btnValue1.Visible:= False;
btnValue2.Visible:= False;
end;
end;
end;