More Hash - Part II

Taking the same approach and design as Part I of this 'post' here is the resulting code for 'hashing' Delphi style. Again, this uses the System.Security.Cryptography Namespace to compute the hash values. This application used the MD5, SHA1,SHA2566, SHA384 and SHA512 classes. I did change the visibility of some of the functions as compared to the 'other' version.

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;

Posted on Monday, December 18, 2006 9:31 PM by Brad Prendergast

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Is it a Hash Brown?

It has been one crazy semester (I think the lack of activity can vouch for that). I've come up to the surface and see that a lot of the landscape has changed, take the emergence of CodeGear for example. I am hoping this is a breathe of new life that can revitalize the Delphi community and not just a last ditch effort (personally I think the BDS IDE is far better for development than VS). I am optimistic about the whole thing and hope they endure the 'rebirth process'.

As I was submerged in my own little world for a period of time, I had the need to calculate the Hash value for files. This actually turned out to server two purposes. The first being the verification of a file as original (intact) by comparing the hash value of the current and original file. Second, it turned out to be a fast way of identifying identical files. Often times a CRC is used to calculate a checksum, however I opted to make use of the System.Security.Cryptography Namespace. This Namespace has a number of useful hash functions including SHA1, SHA256 and SHA512. Surprisingly (or not) these are relatively easy to use and eliminate the need to formulate the algorithm on your own. Here it is in a couple of worlds:

Delphi:

uses
System.Security.Cryptography, System.IO;

procedure frmMain.ClearForm;
begin
txtSHA1.Text:= '';
txtSHA256.Text:= '';
txtSHA512.Text:= '';
end;

procedure frmMain.txtFileName_TextChanged(sender: System.Object; e: System.EventArgs);
begin
ToolTip1.SetToolTip(txtFileName,txtFileName.Text);
end;

procedure frmMain.btnCalculate_Click(sender: System.Object; e: System.EventArgs);
var
myCursor: System.Windows.Forms.Cursor;
oFileStream: FileStream;
lBytes: int64;
instance: FileInfo;
filecontents: Array of Byte;
result: Array of Byte;
SHA1M: SHA1Managed;
SHA256M: SHA256Managed;
SHA512M: SHA512Managed;

begin
myCursor:= Cursor;
Cursor:= Cursors.WaitCursor;
try
try
if not(txtFileName.Text='') then
begin
ErrorProvider1.SetError(btnFile,'');

instance:= FileInfo.Create(txtFileName.Text);
oFileStream:= instance.OpenRead;
lBytes:= oFileStream.Length;
SetLength(filecontents,lBytes);
oFileStream.Read(filecontents,0,lBytes);
oFileStream.Close;

SHA1M:= SHA1Managed.Create;
result:= SHA1M.ComputeHash(filecontents);
txtSHA1.Text:= Convert.ToBase64String(result);

SHA256M:= SHA256Managed.Create;
result:= SHA256M.ComputeHash(filecontents);
txtSHA256.Text:= Convert.ToBase64String(result);

SHA512M:= SHA512Managed.Create;
result:= SHA512M.ComputeHash(filecontents);
txtSHA512.Text:= Convert.ToBase64String(result);
end
else
begin
ErrorProvider1.SetError(btnFile,'Select a filename');
end;
except
on e: exception do
MessageBox.Show(e.Message, e.Source, MessageBoxButtons.OK,
MessageBoxIcon.Error);
end;
finally
Cursor:= myCursor;
end;
end;

procedure frmMain.btnFile_Click(sender: System.Object; e: System.EventArgs);
begin
if (ofdFileName.ShowDialog = System.Windows.Forms.DialogResult.OK) then
begin
ClearForm;
txtFileName.Text:= ofdFileName.FileName;
end;
end;

VB:

Imports System.Security.Cryptography
Imports System.IO

Public Class frmMain

Private Sub btnFile_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFile.Click
If ofdFileName.ShowDialog Then
ClearForm()
txtFileName.Text = ofdFileName.FileName
End If
End Sub

Private Sub txtFileName_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtFileName.TextChanged
ToolTip1.SetToolTip(txtFileName, txtFileName.Text)
End Sub

Private Sub ClearForm()
txtSHA1.Text = ""
txtSHA256.Text = ""
txtSHA512.Text = ""
End Sub

Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
Dim myCursor As Cursor
Dim oFileStream As System.IO.FileStream
Dim lBytes As Long
Dim result() As Byte

myCursor = Cursor
Cursor = Cursors.WaitCursor
Try

If Not (txtFileName.Text = "") Then
ErrorProvider1.Clear() 'Introduced .NET 2.0

Dim instance As New FileInfo(txtFileName.Text)
oFileStream = instance.OpenRead()
lBytes = oFileStream.Length
Dim filecontents(lBytes) As Byte
oFileStream.Read(filecontents, 0, lBytes)
oFileStream.Close()

Dim sha1M As New SHA1Managed
result = sha1M.ComputeHash(filecontents)
txtSHA1.Text = Convert.ToBase64String(result)

Dim sha256M As New SHA256Managed
result = sha256M.ComputeHash(filecontents)
txtSHA256.Text = Convert.ToBase64String(result)

Dim sha512M As New SHA512Managed
result = sha512M.ComputeHash(filecontents)
txtSHA512.Text = Convert.ToBase64String(result)
Else
ErrorProvider1.SetError(btnFile, "Select a filename")
End If

Catch ex As Exception
MessageBox.Show(ex.Message, ex.Source, MessageBoxButtons.OK, MessageBoxIcon.Error)

Finally
Cursor = myCursor
End Try
End Sub

End Class

This is another post done with Live Writer, I think it is pretty 'groovy'.

Posted on Sunday, December 17, 2006 8:04 AM by Brad Prendergast

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TShellExecuteInfo

In keeping with the posting of old sample snippets in my projects folder; ShellExecuteEx can be used to perform an action such as edit, print, open or properties display on a file. A ShellExecuteInfo structure is passed to the ShellExecuteEx function. A sample of how to display a file's properties dialog is as follows:



uses
ShellAPI;
procedure MyShellExecuteInfo(const filename: string; iVerb: integer);
var
sei: TShellExecuteInfo;
Buffer: array[0..MAX_PATH] of Char;
begin
FillChar(sei,sizeof(sei),0);
sei.cbSize:= sizeof(sei);
sei.lpFile:= PAnsiChar(filename);
// sei.lpDirectory and sei.lpIDList
Case iVerb of
0: sei.lpVerb:= 'properties';
1: sei.lpVerb:= 'open';
2: sei.lpVerb:= 'edit';
3: sei.lpVerb:= 'explore';
4: sei.lpVerb:= 'print';
end;
sei.fMask:= SEE_MASK_INVOKEIDLIST;
sei.nShow:= SW_SHOWNORMAL;
ShellExecuteEx(@sei);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
MyShellExecuteInfo(FileEdit1.Text,RadioGroup1.ItemIndex);
end;

Posted on Wednesday, August 30, 2006 6:43 AM by Brad Prendergast

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