i want to make a program written in vb.net which will take text file and a image file,after that the ouput will be the hidden text in a image so that no one can steal data from that image only sender can hide that data in a image and the recipient can unhide that data using key and that application can somebody write a program for hidding data

try this

    'By manipulating the bytes in a picture file this program adds strings to the picture file
    'Without distorting the image
    Public Class Form1
        Dim PicBuffer As System.IO.FileInfo
        Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
            openPic.Title = "Open Picture Files"
        End Sub

        Private Sub openPic_FileOk(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles openPic.FileOk
            PictureBox1.Image = Image.FromFile(openPic.FileName)
            PicBuffer = New System.IO.FileInfo(openPic.FileName)
            ResizeFileName(openPic.FileName, PicBuffer.Name)
        End Sub

        Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
            Dim Ready As Boolean = True
            Dim PicFileStream As System.IO.FileStream
                PicFileStream = PicBuffer.OpenRead
            Catch ex As Exception
                Ready = False
                MsgBox("Please load a picture before clicking this button", MsgBoxStyle.Critical, "Error")
            End Try
            If Ready = True Then
                Dim PicBytes As Long = PicFileStream.Length
                Dim PicExt As String = PicBuffer.Extension
                Dim PicByteArray(PicBytes) As Byte
                PicFileStream.Read(PicByteArray, 0, PicBytes)
                Dim SentinelString() As Byte = {73, 116, 83, 116, 97, 114, 116, 115, 72, 101, 114, 101}
                If RadioButton1.Checked = True Then
                    Dim PlainText As String = TextBox1.Text
                    Dim PlainTextByteArray(PlainText.Length) As Byte
                    For i As Integer = 0 To (PlainText.Length - 1)
                        PlainTextByteArray(i) = CByte(AscW(PlainText.Chars(i)))
                    Dim PicAndText(PicBytes + PlainText.Length + SentinelString.Length) As Byte
                    For t As Long = 0 To (PicBytes - 1)
                        PicAndText(t) = PicByteArray(t)
                    Dim count As Integer = 0
                    For r As Long = PicBytes To (PicBytes + (SentinelString.Length) - 1)
                        PicAndText(r) = SentinelString(count)
                        count += 1
                    count = 0
                    For q As Long = (PicBytes + SentinelString.Length) To (PicBytes + SentinelString.Length + PlainText.Length - 1)
                        PicAndText(q) = PlainTextByteArray(count)
                        count += 1
                    Dim NewFileName As String = buildPic.FileName
                    My.Computer.FileSystem.WriteAllBytes(NewFileName, PicAndText, False)

                ElseIf RadioButton2.Checked Then
                    Dim OutterSearch, InnerSearch, StopSearch As Boolean
                    OutterSearch = True
                    InnerSearch = True
                    StopSearch = False
                    Dim count As Long = 0
                    Dim leftCounter As Long
                    Dim rightCounter As Integer
                    leftCounter = 0
                    rightCounter = 0
                    Do While (count < (PicBytes - SentinelString.Length) And StopSearch = False)
                        If (PicByteArray(count) = SentinelString(0)) Then
                            leftCounter = count + 1
                            rightCounter = 1
                            InnerSearch = True
                            Do While (InnerSearch = True) And (rightCounter < SentinelString.Length) _
                            And (leftCounter < PicByteArray.Length)
                                If (PicByteArray(leftCounter) = SentinelString(rightCounter)) Then
                                    rightCounter += 1
                                    leftCounter += 1
                                    If (rightCounter = (SentinelString.Length - 1)) Then
                                        StopSearch = True
                                    End If
                                    InnerSearch = False
                                    count += 1
                                End If
                            count += 1
                        End If
                    If StopSearch = True Then
                        'leftCounter contains the starting string that is being retrieved
                        Do While (leftCounter < PicBytes)
                            'Bytes need to be converted to an integer 
                            'then to an unicode character which will be the plaintext
                            leftCounter += 1
                        TextBox3.Text = "The Picture does not contain any text"
                    End If

                End If
            End If

        End Sub

        Sub ResizeFileName(ByVal LongFileName As String, ByVal ShortFileName As String)
            If LongFileName.Length > 71 Then
                Dim LongFileNameSize As Integer = LongFileName.Length
                Dim ShortFileNameSize As Integer = ShortFileName.Length
                Dim Cut As Integer = 71 - (5 + ShortFileNameSize)
                Dim i As Integer
                For i = 0 To (Cut) - 1
                For i = 0 To 4
                For i = 0 To (ShortFileNameSize - 1)
                TextBox2.Text = LongFileName
            End If

        End Sub

        Private Sub RadioButton2_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton2.CheckedChanged
            TextBox1.Enabled = False
        End Sub

        Private Sub RadioButton1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton1.CheckedChanged
            TextBox1.Enabled = True
        End Sub
    End Class

As far as I know there are two approaches to do this (I'm sure that there are more but I only know the following two):
1) Adding you text at the end of the image binary data.
2) Modifying some pixels and write your text in them.

I found the following links that I think will help:
I used leadtools, a third party sdk to do this because it also provided additional image processing features that I needed.

However, if you only want to embed text into your image, I did a quick search and found the following project:

Hum. This really sound as a scam to hide and share virus and spyware. But anyway hope you use the solution as per what you said you are doing. I'm not judging you though.

This article has been dead for over six months. Start a new discussion instead.