C_DecryptUpdate() public method

Continues a multi-part decryption operation, processing another encrypted data part
public C_DecryptUpdate ( uint session, byte encryptedPart, uint encryptedPartLen, byte part, uint &partLen ) : CKR
session uint The session's handle
encryptedPart byte Encrypted data part
encryptedPartLen uint Length of the encrypted data part
part byte /// If set to null then the length of decrypted data part is returned in "partLen" parameter, without actually returning decrypted data part. /// If not set to null then "partLen" parameter must contain the lenght of part array and decrypted data part is returned in "part" parameter. ///
partLen uint Location that holds the length of the decrypted data part
return CKR
        public void _02_EncryptAndDecryptMultiPartTest()
        {
            if (Platform.UnmanagedLongSize != 4 || Platform.StructPackingSize != 0)
                Assert.Inconclusive("Test cannot be executed on this platform");

            CKR rv = CKR.CKR_OK;
            
            using (Pkcs11 pkcs11 = new Pkcs11(Settings.Pkcs11LibraryPath))
            {
                rv = pkcs11.C_Initialize(Settings.InitArgs40);
                if ((rv != CKR.CKR_OK) && (rv != CKR.CKR_CRYPTOKI_ALREADY_INITIALIZED))
                    Assert.Fail(rv.ToString());
                
                // Find first slot with token present
                uint slotId = Helpers.GetUsableSlot(pkcs11);
                
                uint session = CK.CK_INVALID_HANDLE;
                rv = pkcs11.C_OpenSession(slotId, (CKF.CKF_SERIAL_SESSION | CKF.CKF_RW_SESSION), IntPtr.Zero, IntPtr.Zero, ref session);
                if (rv != CKR.CKR_OK)
                    Assert.Fail(rv.ToString());
                
                // Login as normal user
                rv = pkcs11.C_Login(session, CKU.CKU_USER, Settings.NormalUserPinArray, Convert.ToUInt32(Settings.NormalUserPinArray.Length));
                if (rv != CKR.CKR_OK)
                    Assert.Fail(rv.ToString());
                
                // Generate symetric key
                uint keyId = CK.CK_INVALID_HANDLE;
                rv = Helpers.GenerateKey(pkcs11, session, ref keyId);
                if (rv != CKR.CKR_OK)
                    Assert.Fail(rv.ToString());
                
                // Generate random initialization vector
                byte[] iv = new byte[8];
                rv = pkcs11.C_GenerateRandom(session, iv, Convert.ToUInt32(iv.Length));
                if (rv != CKR.CKR_OK)
                    Assert.Fail(rv.ToString());
                
                // Specify encryption mechanism with initialization vector as parameter.
                // Note that CkmUtils.CreateMechanism() automaticaly copies iv into newly allocated unmanaged memory.
                CK_MECHANISM mechanism = CkmUtils.CreateMechanism(CKM.CKM_DES3_CBC, iv);
                
                byte[] sourceData = ConvertUtils.Utf8StringToBytes("Our new password");
                byte[] encryptedData = null;
                byte[] decryptedData = null;

                // Multipart encryption functions C_EncryptUpdate and C_EncryptFinal can be used i.e. for encryption of streamed data
                using (MemoryStream inputStream = new MemoryStream(sourceData), outputStream = new MemoryStream())
                {
                    // Initialize encryption operation
                    rv = pkcs11.C_EncryptInit(session, ref mechanism, keyId);
                    if (rv != CKR.CKR_OK)
                        Assert.Fail(rv.ToString());

                    // Prepare buffer for source data part
                    // Note that in real world application we would rather use bigger buffer i.e. 4096 bytes long
                    byte[] part = new byte[8];

                    // Prepare buffer for encrypted data part
                    // Note that in real world application we would rather use bigger buffer i.e. 4096 bytes long
                    byte[] encryptedPart = new byte[8];
                    uint encryptedPartLen = Convert.ToUInt32(encryptedPart.Length);

                    // Read input stream with source data
                    int bytesRead = 0;
                    while ((bytesRead = inputStream.Read(part, 0, part.Length)) > 0)
                    {
                        // Encrypt each individual source data part
                        encryptedPartLen = Convert.ToUInt32(encryptedPart.Length);
                        rv = pkcs11.C_EncryptUpdate(session, part, Convert.ToUInt32(bytesRead), encryptedPart, ref encryptedPartLen);
                        if (rv != CKR.CKR_OK)
                            Assert.Fail(rv.ToString());

                        // Append encrypted data part to the output stream
                        outputStream.Write(encryptedPart, 0, Convert.ToInt32(encryptedPartLen));
                    }

                    // Get the length of last encrypted data part in first call
                    byte[] lastEncryptedPart = null;
                    uint lastEncryptedPartLen = 0;
                    rv = pkcs11.C_EncryptFinal(session, null, ref lastEncryptedPartLen);
                    if (rv != CKR.CKR_OK)
                        Assert.Fail(rv.ToString());
                    
                    // Allocate array for the last encrypted data part
                    lastEncryptedPart = new byte[lastEncryptedPartLen];

                    // Get the last encrypted data part in second call
                    rv = pkcs11.C_EncryptFinal(session, lastEncryptedPart, ref lastEncryptedPartLen);
                    if (rv != CKR.CKR_OK)
                        Assert.Fail(rv.ToString());

                    // Append the last encrypted data part to the output stream
                    outputStream.Write(lastEncryptedPart, 0, Convert.ToInt32(lastEncryptedPartLen));

                    // Read whole output stream to the byte array so we can compare results more easily
                    encryptedData = outputStream.ToArray();
                }

                // Do something interesting with encrypted data

                // Multipart decryption functions C_DecryptUpdate and C_DecryptFinal can be used i.e. for decryption of streamed data
                using (MemoryStream inputStream = new MemoryStream(encryptedData), outputStream = new MemoryStream())
                {
                    // Initialize decryption operation
                    rv = pkcs11.C_DecryptInit(session, ref mechanism, keyId);
                    if (rv != CKR.CKR_OK)
                        Assert.Fail(rv.ToString());

                    // Prepare buffer for encrypted data part
                    // Note that in real world application we would rather use bigger buffer i.e. 4096 bytes long
                    byte[] encryptedPart = new byte[8];

                    // Prepare buffer for decrypted data part
                    // Note that in real world application we would rather use bigger buffer i.e. 4096 bytes long
                    byte[] part = new byte[8];
                    uint partLen = Convert.ToUInt32(part.Length);

                    // Read input stream with encrypted data
                    int bytesRead = 0;
                    while ((bytesRead = inputStream.Read(encryptedPart, 0, encryptedPart.Length)) > 0)
                    {
                        // Decrypt each individual encrypted data part
                        partLen = Convert.ToUInt32(part.Length);
                        rv = pkcs11.C_DecryptUpdate(session, encryptedPart, Convert.ToUInt32(bytesRead), part, ref partLen);
                        if (rv != CKR.CKR_OK)
                            Assert.Fail(rv.ToString());

                        // Append decrypted data part to the output stream
                        outputStream.Write(part, 0, Convert.ToInt32(partLen));
                    }

                    // Get the length of last decrypted data part in first call
                    byte[] lastPart = null;
                    uint lastPartLen = 0;
                    rv = pkcs11.C_DecryptFinal(session, null, ref lastPartLen);
                    if (rv != CKR.CKR_OK)
                        Assert.Fail(rv.ToString());

                    // Allocate array for the last decrypted data part
                    lastPart = new byte[lastPartLen];

                    // Get the last decrypted data part in second call
                    rv = pkcs11.C_DecryptFinal(session, lastPart, ref lastPartLen);
                    if (rv != CKR.CKR_OK)
                        Assert.Fail(rv.ToString());

                    // Append the last decrypted data part to the output stream
                    outputStream.Write(lastPart, 0, Convert.ToInt32(lastPartLen));

                    // Read whole output stream to the byte array so we can compare results more easily
                    decryptedData = outputStream.ToArray();
                }

                // Do something interesting with decrypted data
                Assert.IsTrue(Convert.ToBase64String(sourceData) == Convert.ToBase64String(decryptedData));

                // In LowLevelAPI we have to free unmanaged memory taken by mechanism parameter (iv in this case)
                UnmanagedMemory.Free(ref mechanism.Parameter);
                mechanism.ParameterLen = 0;
                
                rv = pkcs11.C_DestroyObject(session, keyId);
                if (rv != CKR.CKR_OK)
                    Assert.Fail(rv.ToString());
                
                rv = pkcs11.C_Logout(session);
                if (rv != CKR.CKR_OK)
                    Assert.Fail(rv.ToString());
                
                rv = pkcs11.C_CloseSession(session);
                if (rv != CKR.CKR_OK)
                    Assert.Fail(rv.ToString());
                
                rv = pkcs11.C_Finalize(IntPtr.Zero);
                if (rv != CKR.CKR_OK)
                    Assert.Fail(rv.ToString());
            }
        }