AES problème de chiffrement via les sockets

Version imprimable

Bonjour,

Je sais que lors du chiffrement avec AES, on utilise ConvertFromString and ConvertToString mais en utilisant les sockets, je dois rester en byte et lors du déchiffrement par le serveur, le serveur transmet une erreur : "The padding is invalid and cannot be removed."
Partie serveur :

Code:

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Friend Function serverconnexion(ByVal sender As System.Object, e As System.EventArgs)
        Try
            Dim c As New TcpListener(Net.IPAddress.Parse("127.0.0.1"), "7008")
            c.Start()
            Console.WriteLine("starting...")
            Dim a As TcpClient = c.AcceptTcpClient()
            Dim b As New NetworkStream(a.Client)
            Dim rsachiffrement As New System.Security.Cryptography.RSACryptoServiceProvider
            b.Write(System.Text.Encoding.UTF8.GetBytes(rsachiffrement.ToXmlString(False)), 0, System.Text.Encoding.UTF8.GetBytes(rsachiffrement.ToXmlString(False)).Count)
            Dim rsa1(a.ReceiveBufferSize) As Byte
            Dim index As Integer = b.Read(rsa1, 0, a.ReceiveBufferSize)
            Dim rsa2(index - 1) As Byte
            For i = 0 To index - 1
                rsa2(i) = rsa1(i)
            Next
            Dim rsa() As Byte = rsachiffrement.Decrypt(rsa2, False)
            Dim aeschiffrement As New System.Security.Cryptography.AesCryptoServiceProvider
            aeschiffrement.Mode = Security.Cryptography.CipherMode.CFB
            Buffer.BlockCopy(rsa, 0, aeschiffrement.Key, 0, 32)
            Buffer.BlockCopy(rsa, 32, aeschiffrement.IV, 0, 16)
            Dim aesencryptor = aeschiffrement.CreateEncryptor
            Dim aesdecryptor = aeschiffrement.CreateDecryptor
            Dim aes1(a.ReceiveBufferSize) As Byte
            Dim index1 As Integer = b.Read(aes1, 0, a.ReceiveBufferSize)
            Dim aes2(index1 - 1) As Byte
            For i = 0 To index1 - 1
                aes2(i) = aes1(i)
            Next
            Dim aes As New MemoryStream
            Using s As New System.Security.Cryptography.CryptoStream(aes, aesdecryptor, Security.Cryptography.CryptoStreamMode.Write)
                s.Write(aes2, 0, aes2.Count)
            End Using
            Console.WriteLine("Longueur serveur : " & aes.Length)
            Console.WriteLine("Server : " & aes.ToArray.Count)
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Function

Partie cliente :

Code:

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Dim a As New TcpClient
        Console.WriteLine("starting2...")
        a.Connect("127.0.0.1", "7008")
        Console.WriteLine("Ok")
        Dim b As New NetworkStream(a.Client)
        Dim rsa(a.ReceiveBufferSize) As Byte
        b.Read(rsa, 0, a.ReceiveBufferSize)
        'Fabrication de la clé aléatoire
        Dim key As String = ""
        Dim characters As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwyz0123456789"
        Randomize()
        For i = 0 To 16
            key += characters(Math.Floor(Rnd() * characters.Length))
        Next
        Dim process As New System.Security.Cryptography.Rfc2898DeriveBytes(key, 8, 10000)
        Dim keytoencrypt() As Byte = process.GetBytes(48)
        Dim rsachiffrement As New System.Security.Cryptography.RSACryptoServiceProvider
        rsachiffrement.FromXmlString(System.Text.Encoding.UTF8.GetString(rsa))
        b.Write(rsachiffrement.Encrypt(keytoencrypt, False), 0, rsachiffrement.Encrypt(keytoencrypt, False).Count)
        Dim aeschiffrement As New System.Security.Cryptography.AesCryptoServiceProvider
        aeschiffrement.Mode = System.Security.Cryptography.CipherMode.CFB
        Buffer.BlockCopy(keytoencrypt, 0, aeschiffrement.Key, 0, 32)
        Buffer.BlockCopy(keytoencrypt, 32, aeschiffrement.IV, 0, 16)
        Dim aesencryptor = aeschiffrement.CreateEncryptor
        Dim aesdecryptor = aeschiffrement.CreateDecryptor
        Dim aes As New MemoryStream
        Using s As New System.Security.Cryptography.CryptoStream(aes, aesencryptor, System.Security.Cryptography.CryptoStreamMode.Write)
            s.Write(System.Text.Encoding.UTF8.GetBytes(getinfos), 0, System.Text.Encoding.UTF8.GetBytes(getinfos).Count)
        End Using
        b.Write(aes.ToArray, 0, aes.ToArray.Count)
        Console.WriteLine("Longueur : " & aes.Length)
        Console.WriteLine("Client : " & getinfos)

La longueur reçue des deux côtés est correct, les clés sont transmises correctement (je l'ai testé), le seul problème est donc le déchiffrement par AES via la clé et le IV envoyé qui ne fonctionne pas. getinfos() renvoie des données au format String séparés par des ":" tels que "A:B:C:D:10/10/1976:E". Quelqu'un a-t-il une idée? Merci.

1 pièce(s) jointe(s)

Bon, j'ai réussi à trouver l'endroit où ça ne marche pas, c'est à la réception de la clé aléatoire généré par le client et dérivé par RFC2008. Voici ci-dessous le code modifié et la fenêtre du log :
Partie serveur :

Code:

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Friend Function serverconnexion(ByVal sender As System.Object, e As System.EventArgs)
        Try
            Dim c As New TcpListener(Net.IPAddress.Parse("127.0.0.1"), "7008")
            c.Start()
            Console.WriteLine("starting...")
            Dim a As TcpClient = c.AcceptTcpClient()
            Dim b As New NetworkStream(a.Client)
            Dim rsachiffrement As New System.Security.Cryptography.RSACryptoServiceProvider
            b.Write(System.Text.Encoding.UTF8.GetBytes(rsachiffrement.ToXmlString(False)), 0, System.Text.Encoding.UTF8.GetBytes(rsachiffrement.ToXmlString(False)).Count)
            b.Flush()
            Console.WriteLine("Public key envoyé:" & rsachiffrement.ToXmlString(False))
            Dim rsa1(a.ReceiveBufferSize) As Byte
            Dim index = b.Read(rsa1, 0, a.ReceiveBufferSize)
            b.Flush()
            Dim rsa2(index - 1) As Byte
            For i = 0 To index - 1
                rsa2(i) = rsa1(i)
            Next
            Dim text As String = ""
            For i = 0 To rsa2.Count - 1
                text += rsa2(i).ToString("x2")
            Next
            Console.WriteLine("Key reçue:" & text)
            Dim rsa() As Byte = rsachiffrement.Decrypt(rsa2, False)
            Dim aeschiffrement As New System.Security.Cryptography.AesCryptoServiceProvider
            aeschiffrement.Mode = Security.Cryptography.CipherMode.CBC
            Buffer.BlockCopy(rsa, 0, aeschiffrement.Key, 0, 32)
            Buffer.BlockCopy(rsa, 32, aeschiffrement.IV, 0, 16)
            Dim key As String = ""
            Dim IV As String = ""
            For i = 0 To aeschiffrement.Key.Count - 1
                key += aeschiffrement.Key(i).ToString("x2")
            Next
            For i = 0 To aeschiffrement.IV.Count - 1
                IV += aeschiffrement.IV(i).ToString("x2")
            Next
            Console.WriteLine(key & ":" & IV)
            Dim aesencryptor = aeschiffrement.CreateEncryptor
            Dim aesdecryptor = aeschiffrement.CreateDecryptor
            Dim aes1(a.ReceiveBufferSize) As Byte
            Dim index1 As Integer = b.Read(aes1, 0, a.ReceiveBufferSize)
            b.Flush()
            Dim aes2(index1 - 1) As Byte
            For i = 0 To index1 - 1
                aes2(i) = aes1(i)
            Next
            IO.File.WriteAllBytes("decrypted.txt", aes2)
            aes2 = Convert.FromBase64String(IO.File.ReadAllText("decrypted.txt"))
            IO.File.Delete("decrypted.txt")
            Dim aes As New MemoryStream
            Using s As New System.Security.Cryptography.CryptoStream(aes, aesdecryptor, Security.Cryptography.CryptoStreamMode.Write)
                s.Write(aes2, 0, aes2.Count)
            End Using
            Console.WriteLine("Longueur serveur : " & aes.ToArray.Count)
            Console.WriteLine("Server : " & System.Text.Encoding.UTF8.GetString(aes2))
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Function

Partie cliente :

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Dim a As New TcpClient
        Console.WriteLine("starting2...")
        a.Connect("127.0.0.1", "7008")
        Console.WriteLine("Ok")
        Dim b As New NetworkStream(a.Client)
        Dim prersa(a.ReceiveBufferSize) As Byte
        Dim index = b.Read(prersa, 0, a.ReceiveBufferSize)
        b.Flush()
        Dim rsa(index - 1) As Byte
        For i = 0 To index - 1
            rsa(i) = prersa(i)
        Next
        Console.WriteLine("Public key reçue:" & System.Text.Encoding.UTF8.GetString(rsa))
        'Fabrication de la clé aléatoire
        Dim key As String = ""
        Dim characters As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwyz0123456789"
        Randomize()
        For i = 0 To 16
            key += characters(Math.Floor(Rnd() * characters.Length))
        Next
        Dim process As New System.Security.Cryptography.Rfc2898DeriveBytes(key, 8, 10000)
        Dim keytoencrypt() As Byte = process.GetBytes(48)
        Dim rsachiffrement As New System.Security.Cryptography.RSACryptoServiceProvider
        b.Write(rsachiffrement.Encrypt(keytoencrypt, False), 0, rsachiffrement.Encrypt(keytoencrypt, False).Count)
        b.Flush()
        Dim text As String = ""
        For i = 0 To rsachiffrement.Encrypt(keytoencrypt, False).Count - 1
            text += rsachiffrement.Encrypt(keytoencrypt, False)(i).ToString("x2")
        Next
        Console.WriteLine("Key : " & text)
        Dim aeschiffrement As New System.Security.Cryptography.AesCryptoServiceProvider
        aeschiffrement.Mode = System.Security.Cryptography.CipherMode.CBC
        Buffer.BlockCopy(keytoencrypt, 0, aeschiffrement.Key, 0, 32)
        Buffer.BlockCopy(keytoencrypt, 32, aeschiffrement.IV, 0, 16)
        Dim key1 As String = ""
        Dim IV1 As String = ""
        For i = 0 To aeschiffrement.Key.Count - 1
            key1 += aeschiffrement.Key(i).ToString("x2")
        Next
        For i = 0 To aeschiffrement.IV.Count - 1
            IV1 += aeschiffrement.IV(i).ToString("x2")
        Next
        Console.WriteLine(key1 & ":" & IV1)
        Dim aesencryptor = aeschiffrement.CreateEncryptor
        Dim aesdecryptor = aeschiffrement.CreateDecryptor
        Dim aes As New MemoryStream
        Using s As New System.Security.Cryptography.CryptoStream(aes, aesencryptor, System.Security.Cryptography.CryptoStreamMode.Write)
            s.Write(System.Text.Encoding.UTF8.GetBytes(getinfos), 0, System.Text.Encoding.UTF8.GetBytes(getinfos).Count)
        End Using
        IO.File.WriteAllText("crypted.txt", Convert.ToBase64String(aes.ToArray))
        b.Write(IO.File.ReadAllBytes("crypted.txt"), 0, IO.File.ReadAllBytes("crypted.txt").Count)
        b.Flush()
        IO.File.Delete("crypted.txt")
        Console.WriteLine("Longueur : " & aes.ToArray.Count)
        Console.WriteLine("Client : " & getinfos)

Log :
Pièce jointe 223815

Alors, voici le problème, j'ai BufferCopy qui ne fonctionne pas.

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Dim rsa() As Byte = rsachiffrement.Decrypt(rsa2, False)
            Console.WriteLine("ServerKey:{0}", Convert.ToBase64String(rsa))
            Dim aeschiffrement As New System.Security.Cryptography.AesCryptoServiceProvider
            Array.Clear(aeschiffrement.Key, 0, aeschiffrement.Key.Count)
            Array.Clear(aeschiffrement.IV, 0, aeschiffrement.IV.Count)
            For i = 0 To 31
                aeschiffrement.Key(i) = rsa(i)
            Next
            For i = 32 To 47
                aeschiffrement.IV(i - 32) = rsa(i)
            Next
            Console.WriteLine("Serveur:{0}", Convert.ToBase64String(aeschiffrement.Key))

La clé AES et le vecteur d'initialisation (IV) ne change pas malgré mon changement, j'ai même essayé avec BufferCopy mais ça ne fonctionne pas, quelqu'un aurait-il une piste? Merci.