Discussion :

[Cybercope]

Bonjours à tous !

Je rencontre un problème assez pénible. Je développe un logiciel qui utilise la cryptographie. Celui ci crypte une string avant d'écrire la string cryptée dans un fichier .txt . Cependant, je rencontre un problème à la lecture.

L'algorithme utilisé est AES.

Voici mon code :

Code :

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Imports System.IO
Imports System.Security.Cryptography
 
Public Class Client
 
#Region "Variables"
 
    Dim Counter1 As Integer = 0
    Dim path As String = "J:\test.txt"
    Dim myAes As Aes = Aes.Create()
 
#End Region
 
#Region "Procédures"
 
    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        crypt()
    End Sub
 
    Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
        decrypt()
    End Sub
 
#End Region
 
#Region "CRYPT"
 
    Private Sub crypt()
 
 
        Dim sw As StreamWriter = New StreamWriter(path, False)
 
 
        For i = 0 To ListBox1.Items.Count - 1 Step 1
 
                Dim original As String = AssemblyTextForCrypt(i)
                Dim encrypted As Byte() = EncrypText(original, myAes.Key, myAes.IV)
                Dim Final As String = System.Text.Encoding.Unicode.GetString(encrypted)
                sw.WriteLine(Final)
            Next
            sw.Flush()
        sw.Close()
    End Sub
 
    Function AssemblyTextForCrypt(ByVal index As Integer)
 
        Dim assembly As String = ""
        assembly = ListBox1.Items.Item(index) + "|" + ListBox2.Items.Item(index) + "|" + ListBox3.Items.Item(index) + "|" + ListBox4.Items.Item(index)
        Return assembly
 
    End Function
 
    Function EncrypText(ByVal Text As String, ByVal Key() As Byte, ByVal IV() As Byte) As Byte()
 
        Dim encrypted() As Byte
        ' Create an Aes object
        ' with the specified key and IV.
 
        ' Create a decrytor to perform the stream transform.
        Dim encryptor As ICryptoTransform = myAes.CreateEncryptor(myAes.Key, myAes.IV)
        ' Create the streams used for encryption.
        Using msEncrypt As New MemoryStream()
            Using csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
                Using swEncrypt As New StreamWriter(csEncrypt)
 
                    'Write all data to the stream.
                    swEncrypt.Write(Text)
                End Using
                encrypted = msEncrypt.ToArray()
            End Using
        End Using
 
        ' Return the encrypted bytes from the memory stream.
        Return encrypted
 
    End Function
 
#End Region
 
#Region "DECRYPT"
 
    Sub decrypt()
 
        Dim sr As StreamReader = New StreamReader(path)
        Dim ligne() As Byte
 
        Do
            ligne = System.Text.Encoding.Unicode.GetBytes(sr.ReadLine)
            Dim decrypted As String = DecrypText(ligne, myAes.Key, myAes.IV)
            MsgBox(ligne.ToString)
            Dim List() As String = DesassemblyForRead(decrypted)
            Place(List)
        Loop Until ligne Is Nothing
        sr.Close()
 
    End Sub
 
    Function DecrypText(ByVal cipherText() As Byte, ByVal Key() As Byte, ByVal IV() As Byte) As String
        ' Declare the string used to hold
        ' the decrypted text.
        Dim plaintext As String = Nothing
 
        ' Create an Aes object
        ' with the specified key and IV.
 
        ' Create a decrytor to perform the stream transform.
        Dim decryptor As ICryptoTransform = myAes.CreateDecryptor(myAes.Key, myAes.IV)
 
        ' Create the streams used for decryption.
        Using msDecrypt As New MemoryStream(cipherText)
 
            Using csDecrypt As New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)
 
                Using srDecrypt As New StreamReader(csDecrypt)
 
                    ' Read the decrypted bytes from the decrypting stream
                    ' and place them in a string.
                    plaintext = srDecrypt.ReadToEnd
 
                End Using
            End Using
        End Using
 
        Return plaintext
 
    End Function 'DecryptStringFromBytes_Aes 
 
 
    Function DesassemblyForRead(ByVal line As String)
 
        Dim List() As String = Nothing
        List = line.Split("|")
        Return List
 
    End Function
 
    Sub Place(ByVal Arr() As String)
        ListBox1.Items.Clear()
        ListBox2.Items.Clear()
        ListBox3.Items.Clear()
        ListBox4.Items.Clear()
        ListBox1.Items.Add(Arr(0))
        ListBox2.Items.Add(Arr(1))
        ListBox3.Items.Add(Arr(2))
        ListBox4.Items.Add(Arr(3))
    End Sub
 
#End Region

Le cryptage et l'écriture se déroule sans problème.

J'ai une erreur du type : System.Security.Cryptography.CryptographicException: Le remplissage n'est pas valide et ne peut pas être supprimé.
sur la ligne

Code :

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 plaintext = srDecrypt.ReadToEnd

J'ai essayer de retourner un tableau de bytes au lieu d'une string mais le problème persiste.

N'étant pas expert en la matière, j'ai du mal a voir d'ou vient cette erreur.

NB: J'ai déjà cherché sur google, mais je n'ai rien trouvé qui fonctionne ou qui puisse m'aider.

Merci de votre aide !

Ind6x

[hacker59]

Bonjour,
voici la solution a ton probléme :

Code :

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Private Sub Decrypt(entrer As String, sortie As String, key As String)
        Dim DES As New DESCryptoServiceProvider()
        DES.Key() = ASCIIEncoding.ASCII.GetBytes(key)
        DES.IV = ASCIIEncoding.ASCII.GetBytes(key)
        Dim fsread As New FileStream(entrer, FileMode.Open, FileAccess.Read)
        Dim desdecrypt As ICryptoTransform = DES.CreateDecryptor()
        Dim cryptostreamDecr As New CryptoStream(fsread, desdecrypt, CryptoStreamMode.Read)
        Dim fsDecrypted As New StreamWriter(sortie)
        fsDecrypted.Write(New StreamReader(cryptostreamDecr).ReadToEnd)
        fsDecrypted.Flush()
        fsDecrypted.Close()
    End Sub
 
    Private Sub Encrypt(entrer As String, sortie As String, key As String)
        Dim fsInput As New FileStream(entrer, FileMode.Open, FileAccess.Read)
        Dim fsEncrypted As New FileStream(sortie, FileMode.Create, FileAccess.Write)
        Dim DES As New DESCryptoServiceProvider()
        DES.Key = ASCIIEncoding.ASCII.GetBytes(key)
        DES.IV = ASCIIEncoding.ASCII.GetBytes(key)
        Dim desencrypt As ICryptoTransform = DES.CreateEncryptor()
        Dim cryptostream As New CryptoStream(fsEncrypted, desencrypt, CryptoStreamMode.Write)
        Dim bytearrayinput(fsInput.Length - 1) As Byte
        fsInput.Read(bytearrayinput, 0, bytearrayinput.Length)
        cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length)
    End Sub
 
    Function CreateKey() As String
        Dim DesC As DESCryptoServiceProvider = DESCryptoServiceProvider.Create()
        Return ASCIIEncoding.ASCII.GetString(DesC.Key)
    End Function

exemple : encrypt(C:\Users\priver\Desktop\teste.txt,C:\Users\priver\Desktop\teste2.txt,CreateKey)

cordialement,

[Cybercope]

Bonjour,

Merci de votre réponse. Cependant, je ne souhaite pas utiliser DES mais AES. De plus, il ne s'agit pas de fichier que je souhaite crypter mais d'un flux.

J'ai retirer les using et end using dans le code source et j'ai fait des déclaration simple avec Dim. Parfois cela fonctionne, mais après le problème resurgit.

Merci

Ind6x

[hacker59]

si vous voulez plus information vous avez la réponde dans ce lien : https://nciphers.com/aes/
Décrypter et encrypter AES.
Cordialement,

[hacker59]

si tu veux un exemple , voici la solution :

Code :

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Imports System.IO
Imports System.Security.Cryptography
Imports System.Text
 
Public Class Form1
    Private SecretKey(15) As Byte
    Private SecretIV(15) As Byte
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim open As New OpenFileDialog
        open.InitialDirectory = My.Computer.FileSystem.SpecialDirectories.Desktop
        open.Filter = "Text Files (.txt)|*.txt"
        If open.ShowDialog = Windows.Forms.DialogResult.OK Then
            TextBox1.Text = open.FileName
        Else
            Exit Sub
        End If
    End Sub
 
    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        Dim save As New SaveFileDialog
        save.InitialDirectory = My.Computer.FileSystem.SpecialDirectories.Desktop
        save.Filter = "Text Files (.txt)|*.txt"
        If save.ShowDialog = Windows.Forms.DialogResult.OK Then
            TextBox2.Text = save.FileName
        Else
            Exit Sub
        End If
    End Sub
 
    Private Sub Button3_Click(sender As System.Object, e As System.EventArgs) Handles Button3.Click
        If TextBox1.Text.Length > 0 OrElse TextBox2.Text.Length > 0 Then
            EncryptFile(TextBox1.Text, TextBox2.Text)
            MessageBox.Show("fichier crypter!")
        Else
            MessageBox.Show("Veuillez séléctionner un fichier entrer et sortie !", "erreur", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End If
    End Sub
 
    Private Sub EncryptFile(ByVal InputFilename As String, ByVal OutputFilename As String)
        Dim AES As New AesCryptoServiceProvider()
        Dim AesDecrypt As ICryptoTransform = AES.CreateEncryptor(SecretKey, SecretIV)
        Using fsInput As New FileStream(InputFilename, FileMode.Open, FileAccess.Read, FileShare.Read)
            Using fsOutput As New FileStream(OutputFilename, FileMode.Create, FileAccess.Write, FileShare.None)
                Using cryptostream As New CryptoStream(fsOutput, AesDecrypt, CryptoStreamMode.Write)
                    Dim bytearrayinput(fsInput.Length - 1) As Byte
                    Dim bytesRead As Long = 0
                    bytesRead = fsInput.Read(bytearrayinput, 0, fsInput.Length)
                    If Not (bytesRead = 0) Then
                        cryptostream.Write(bytearrayinput, 0, bytesRead)
                        cryptostream.Flush()
                    End If
                End Using
            End Using
        End Using
    End Sub
 
    Private Sub Button4_Click(sender As System.Object, e As System.EventArgs) Handles Button4.Click
        If TextBox1.Text.Length > 0 OrElse TextBox2.Text.Length > 0 Then
            DécryptFile(TextBox1.Text, TextBox2.Text)
            MessageBox.Show("Fichier Décrypter!")
        Else
            MessageBox.Show("Veuillez séléctionner un fichier entrer et sortie !", "erreur", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End If
    End Sub
 
    Private Sub DécryptFile(ByVal InputFilename As String, ByVal OutputFilename As String)
        Dim AES As New AesCryptoServiceProvider()
        Dim AesDecrypt As ICryptoTransform = AES.CreateDecryptor(SecretKey, SecretIV)
        Using fsread As New FileStream(InputFilename, FileMode.Open, FileAccess.Read, FileShare.Read)
            Using cryptostreamDecr As New CryptoStream(fsread, AesDecrypt, CryptoStreamMode.Read)
                Using fsDecrypted As New FileStream(OutputFilename, FileMode.Create, FileAccess.Write, FileShare.None)
                    Dim bytearrayinput(fsread.Length) As Byte
                    Dim bytesRead As Long = 0
                    bytesRead = cryptostreamDecr.Read(bytearrayinput, 0, fsread.Length)
                    If (bytesRead > 0) Then
                        fsDecrypted.Write(bytearrayinput, 0, bytesRead)
                        fsDecrypted.Flush()
                    End If
                End Using
            End Using
        End Using
    End Sub
 
End Class