on_data_decrypt Event

Fires to decrypt a block of data using a custom encryption implementation.

Syntax

class CBDriveDataDecryptEventParams(object):
  @property
  def key() -> c_void_p: ...
  @property
  def key_length() -> int: ...
  @property
  def salt1() -> c_void_p: ...
  @property
  def salt_1_size() -> int: ...
  @property
  def salt2() -> c_void_p: ...
  @property
  def salt_2_size() -> int: ...
  @property
  def data() -> c_void_p: ...
  @property
  def data_size() -> int: ...
  @property
  def result_code() -> int: ...
  @result_code.setter
  def result_code(value) -> None: ...

# In class CBDrive:
@property
def on_data_decrypt() -> Callable[[CBDriveDataDecryptEventParams], None]: ...
@on_data_decrypt.setter
def on_data_decrypt(event_hook: Callable[[CBDriveDataDecryptEventParams], None]) -> None: ...

Remarks

This event fires when the class needs to decrypt a block of data using an application-defined encryption implementation. Please refer to the Encryption topic for more information.

This event only needs to be handled by applications that use one of the CBFSSTORAGE_EM_CUSTOM* encryption modes. To handle this event properly, applications must decrypt all DataSize bytes of data in the Data buffer. After decrypting the data, applications must write it back to the Data buffer. The size of the decrypted data must match DataSize, which is always a multiple of 32.

The Key buffer contains the encryption key (e.g., password) specified for the file, alternate stream, or vault whose data is being decrypted. The KeyLength parameter specifies the length, in bytes, of Key.

The Salt1 and Salt2 buffers contain the same salt values provided when the data was encrypted in an earlier on_data_encrypt event. The Salt1Size and Salt2Size parameters specify the length, in bytes, of Salt1 and Salt2.

Please refer to the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource isn't available, security checks failed, etc.), set it to a non-zero value to report an appropriate error. Please refer to the Error Reporting and Handling topic for more information.

Note: An application should not attempt to call class's methods from handlers of this event. Doing this is guaranteed to cause a deadlock.

Note: when a storage is opened concurrently in read-only mode by several applications using CBDrive or CBMemDrive class, the event will fire only in the first application. To prevent such a situation, always open a vault in read-write mode.