PDFDecryptor Class

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The PDFDecryptor class decrypts PDF documents.

Syntax

class secureblackbox.PDFDecryptor

Remarks

PDFDecryptor decrypts PDF documents encrypted with passwords or certificates.

Use PDFDecryptor to decrypt protected PDF documents. The PDF specification offers two encryption types:

• Password-based encryption: only someone who knows the password can decrypt the document.
• Certificate-based encryption: only the person who has the private key matching the encryption certificate can decrypt the document.

Decryption is often used not only to restrict access to the document content, but also to assign specific access permissions. Among such permissions are allowed printing quality, permission to modify or extract content, to fill in forms, and a few others.

To decrypt a document encrypted with a password, simply assign the password to password property. If the provided password matches either one of the 'user' and 'owner' passwords, it will be used to decrypt the document. While PDF allows you to use different passwords for less-restricted owner and more-restricted user, this is rarely used in practice, with the majority of implementations sticking to the same password for both types of users.

To decrypt a document encrypted with a certificate, load the recipient's certificate using CertificateManager or CertificateStorage components and assign it to the decryption_certificate property. The certificate needs to include the associated private key.

You can assign the decryption material before processing the document (if you know beforehand what type of encryption was used), or on-the-fly, upon discovery that a particular document is encrypted. To implement the latter approach, please subscribe to on_encrypted event. This event can fire for one or more times, notifying you of each encryption method that was used to protect the document. You can then assign the password or certificate inside the event handler accordingly.

Once you have decrypted the document, use the > property to check the document permissions, and other properties of the DocumentInfo object to find out the encryption details.

Finally, provide the input and output locations using input_file (or input_bytes) and output_file properties and call the decrypt method to complete the operation. If output_file is not assigned, the encrypted document will be generated in output_bytes. decryptor.InputFile = "encrypted.pdf"; decryptor.OutputFile = "decrypted.pdf"; decryptor.Password = "password"; decryptor.Decrypt();

Property List

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The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the class with short descriptions. Click on the links for further details.

decryption_certificate_bytes Property

Returns the raw certificate data in DER format.

Syntax

def get_decryption_certificate_bytes() -> bytes: ...

decryption_certificate_bytes = property(get_decryption_certificate_bytes, None)

Remarks

Returns the raw certificate data in DER format.

This property is read-only.

decryption_certificate_handle Property

Allows to get or set a 'handle', a unique identifier of the underlying property object.

Syntax

def get_decryption_certificate_handle() -> int: ...
def set_decryption_certificate_handle(value: int) -> None: ...

decryption_certificate_handle = property(get_decryption_certificate_handle, set_decryption_certificate_handle)

Default Value

0

Remarks

Allows to get or set a 'handle', a unique identifier of the underlying property object. Use this property to assign objects of the same type in a quicker manner, without copying them fieldwise.

When you pass a handle of one object to another, the source object is copied to the destination rather than assigned. It is safe to get rid of the original object after such operation. pdfSigner.setSigningCertHandle(certMgr.getCertHandle());

document_info_encryption_algorithm Property

The symmetric algorithm used to encrypt the document.

Syntax

def get_document_info_encryption_algorithm() -> str: ...

document_info_encryption_algorithm = property(get_document_info_encryption_algorithm, None)

Default Value

""

Remarks

The symmetric algorithm used to encrypt the document.

This property contains the encryption algorithm that was used to encrypt the PDF document.

Supported values:

This property is read-only.

document_info_encryption_type Property

The document encryption type.

Syntax

def get_document_info_encryption_type() -> int: ...

document_info_encryption_type = property(get_document_info_encryption_type, None)

Default Value

1

Remarks

The document encryption type.

This property indicates the kind of encryption that was used to encrypt the PDF document.

Supported values:

This property is read-only.

document_info_metadata_encrypted Property

Indicates if the document metadata is encrypted.

Syntax

def get_document_info_metadata_encrypted() -> bool: ...

document_info_metadata_encrypted = property(get_document_info_metadata_encrypted, None)

Default Value

TRUE

Remarks

Indicates if the document metadata is encrypted.

Use this property to check if the document metadata is encrypted.

Metadata contains additional information about the document such as its name and author.

This property is read-only.

document_info_permissions Property

Contains the document permissions associated with the encryption.

Syntax

def get_document_info_permissions() -> int: ...

document_info_permissions = property(get_document_info_permissions, None)

Default Value

0

Remarks

Contains the document permissions associated with the encryption.

Use this property to check the permissions protected by this encryption. The PDF specification expects applications to comply with these permissions when handling encrypted documents. Contains a bit mask of the following flags:

This property is read-only.

external_crypto_async_document_id Property

Specifies an optional document ID for SignAsyncBegin() and SignAsyncEnd() calls.

Syntax

def get_external_crypto_async_document_id() -> str: ...
def set_external_crypto_async_document_id(value: str) -> None: ...

external_crypto_async_document_id = property(get_external_crypto_async_document_id, set_external_crypto_async_document_id)

Default Value

""

Remarks

Specifies an optional document ID for SignAsyncBegin() and SignAsyncEnd() calls.

Use this property when working with multi-signature DCAuth requests and responses to uniquely identify documents signed within a larger batch. On the completion stage, this value helps the signing component identify the correct signature in the returned batch of responses.

If using batched requests, make sure to set this property to the same value on both the pre-signing (SignAsyncBegin) and completion (SignAsyncEnd) stages.

external_crypto_custom_params Property

Custom parameters to be passed to the signing service (uninterpreted).

Syntax

def get_external_crypto_custom_params() -> str: ...
def set_external_crypto_custom_params(value: str) -> None: ...

external_crypto_custom_params = property(get_external_crypto_custom_params, set_external_crypto_custom_params)

Default Value

""

Remarks

Custom parameters to be passed to the signing service (uninterpreted).

external_crypto_data Property

Additional data to be included in the async state and mirrored back by the requestor.

Syntax

def get_external_crypto_data() -> str: ...
def set_external_crypto_data(value: str) -> None: ...

external_crypto_data = property(get_external_crypto_data, set_external_crypto_data)

Default Value

""

Remarks

Additional data to be included in the async state and mirrored back by the requestor.

external_crypto_external_hash_calculation Property

Specifies whether the message hash is to be calculated at the external endpoint.

Syntax

def get_external_crypto_external_hash_calculation() -> bool: ...
def set_external_crypto_external_hash_calculation(value: bool) -> None: ...

external_crypto_external_hash_calculation = property(get_external_crypto_external_hash_calculation, set_external_crypto_external_hash_calculation)

Default Value

FALSE

Remarks

Specifies whether the message hash is to be calculated at the external endpoint. Please note that this mode is not supported by the DCAuth class.

If set to true, the class will pass a few kilobytes of to-be-signed data from the document to the OnExternalSign event. This only applies when SignExternal() is called.

external_crypto_hash_algorithm Property

Specifies the request's signature hash algorithm.

Syntax

def get_external_crypto_hash_algorithm() -> str: ...
def set_external_crypto_hash_algorithm(value: str) -> None: ...

external_crypto_hash_algorithm = property(get_external_crypto_hash_algorithm, set_external_crypto_hash_algorithm)

Default Value

"SHA256"

Remarks

Specifies the request's signature hash algorithm.

external_crypto_key_id Property

The ID of the pre-shared key used for DC request authentication.

Syntax

def get_external_crypto_key_id() -> str: ...
def set_external_crypto_key_id(value: str) -> None: ...

external_crypto_key_id = property(get_external_crypto_key_id, set_external_crypto_key_id)

Default Value

""

Remarks

The ID of the pre-shared key used for DC request authentication.

Asynchronous DCAuth-driven communication requires that parties authenticate each other with a secret pre-shared cryptographic key. This provides an extra protection layer for the protocol and diminishes the risk of the private key becoming abused by foreign parties. Use this property to provide the pre-shared key identifier, and use external_crypto_key_secret to pass the key itself.

The same KeyID/KeySecret pair should be used on the DCAuth side for the signing requests to be accepted.

Note: The KeyID/KeySecret scheme is very similar to the AuthKey scheme used in various Cloud service providers to authenticate users.

Example: signer.ExternalCrypto.KeyID = "MainSigningKey"; signer.ExternalCrypto.KeySecret = "abcdef0123456789";

external_crypto_key_secret Property

The pre-shared key used for DC request authentication.

Syntax

def get_external_crypto_key_secret() -> str: ...
def set_external_crypto_key_secret(value: str) -> None: ...

external_crypto_key_secret = property(get_external_crypto_key_secret, set_external_crypto_key_secret)

Default Value

""

Remarks

The pre-shared key used for DC request authentication. This key must be set and match the key used by the DCAuth counterpart for the scheme to work.

Read more about configuring authentication in the external_crypto_key_id topic.

external_crypto_method Property

Specifies the asynchronous signing method.

Syntax

def get_external_crypto_method() -> int: ...
def set_external_crypto_method(value: int) -> None: ...

external_crypto_method = property(get_external_crypto_method, set_external_crypto_method)

Default Value

0

Remarks

Specifies the asynchronous signing method. This is typically defined by the DC server capabilities and setup.

Available options:

external_crypto_mode Property

Specifies the external cryptography mode.

Syntax

def get_external_crypto_mode() -> int: ...
def set_external_crypto_mode(value: int) -> None: ...

external_crypto_mode = property(get_external_crypto_mode, set_external_crypto_mode)

Default Value

0

Remarks

Specifies the external cryptography mode.

Available options:

external_crypto_public_key_algorithm Property

Provide the public key algorithm here if the certificate is not available on the pre-signing stage.

Syntax

def get_external_crypto_public_key_algorithm() -> str: ...
def set_external_crypto_public_key_algorithm(value: str) -> None: ...

external_crypto_public_key_algorithm = property(get_external_crypto_public_key_algorithm, set_external_crypto_public_key_algorithm)

Default Value

""

Remarks

Provide the public key algorithm here if the certificate is not available on the pre-signing stage.

fips_mode Property

Reserved.

Syntax

def get_fips_mode() -> bool: ...
def set_fips_mode(value: bool) -> None: ...

fips_mode = property(get_fips_mode, set_fips_mode)

Default Value

FALSE

Remarks

This property is reserved for future use.

input_bytes Property

Use this property to pass the input to class in byte array form.

Syntax

def get_input_bytes() -> bytes: ...
def set_input_bytes(value: bytes) -> None: ...

input_bytes = property(get_input_bytes, set_input_bytes)

Remarks

Assign a byte array containing the data to be processed to this property.

input_file Property

The PDF file to be decrypted.

Syntax

def get_input_file() -> str: ...
def set_input_file(value: str) -> None: ...

input_file = property(get_input_file, set_input_file)

Default Value

""

Remarks

Provide the path to the PDF document to be decrypted.

output_bytes Property

Use this property to read the output the class object has produced.

Syntax

def get_output_bytes() -> bytes: ...

output_bytes = property(get_output_bytes, None)

Remarks

Read the contents of this property after the operation has completed to read the produced output. This property will only be set if the output_file and output_stream properties had not been assigned.

This property is read-only.

output_file Property

The file to save the decrypted document to.

Syntax

def get_output_file() -> str: ...
def set_output_file(value: str) -> None: ...

output_file = property(get_output_file, set_output_file)

Default Value

""

Remarks

Specifies the path where the decrypted PDF should be saved.

password Property

The decryption password.

Syntax

def get_password() -> str: ...
def set_password(value: str) -> None: ...

password = property(get_password, set_password)

Default Value

""

Remarks

Use this property to provide the decryption password.

config Method

Sets or retrieves a configuration setting.

Syntax

def config(configuration_string: str) -> str: ...

Remarks

config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

decrypt Method

Decrypts a PDF document.

Syntax

def decrypt() -> None: ...

Remarks

Use this method to decrypt a PDF document provided via input_file (input_stream). The decrypted document will be saved in output_file (output_stream).

do_action Method

Performs an additional action.

Syntax

def do_action(action_id: str, action_params: str) -> str: ...

Remarks

do_action is a generic method available in every class. It is used to perform an additional action introduced after the product major release. The list of actions is not fixed, and may be flexibly extended over time.

The unique identifier (case insensitive) of the action is provided in the ActionID parameter.

ActionParams contains the value of a single parameter, or a list of multiple parameters for the action in the form of PARAM1=VALUE1;PARAM2=VALUE2;....

Common ActionIDs:

reset Method

Resets the class settings.

Syntax

def reset() -> None: ...

Remarks

reset is a generic method available in every class.

on_document_loaded Event

This event is fired when the document has been loaded into memory.

Syntax

class PDFDecryptorDocumentLoadedEventParams(object):
  @property
  def cancel() -> bool: ...
  @cancel.setter
  def cancel(value) -> None: ...

# In class PDFDecryptor:
@property
def on_document_loaded() -> Callable[[PDFDecryptorDocumentLoadedEventParams], None]: ...
@on_document_loaded.setter
def on_document_loaded(event_hook: Callable[[PDFDecryptorDocumentLoadedEventParams], None]) -> None: ...

Remarks

The handler for this event is a good place to check the document structure, which may be useful when preparing the signature. For example, you can use the pages information to find the optimal position for the signature widget.

Set Cancel to true to terminate document processing on this stage.

on_encrypted Event

Notifies the application that the document is encrypted and provides recipient certificate details if asymmetric encryption was used to encrypt the document.

Syntax

class PDFDecryptorEncryptedEventParams(object):
  @property
  def cert_used() -> bool: ...

  @property
  def issuer_rdn() -> str: ...

  @property
  def serial_number() -> bytes: ...

  @property
  def subject_key_id() -> bytes: ...

  @property
  def need_credential() -> bool: ...

  @property
  def skip_this() -> bool: ...
  @skip_this.setter
  def skip_this(value) -> None: ...

# In class PDFDecryptor:
@property
def on_encrypted() -> Callable[[PDFDecryptorEncryptedEventParams], None]: ...
@on_encrypted.setter
def on_encrypted(event_hook: Callable[[PDFDecryptorEncryptedEventParams], None]) -> None: ...

Remarks

The class fires this event when processing encrypted documents to report the fact of encryption and pass certificate parameters to the user.

This event fires repeatedly for each encryption mechanism used in the document until the user provides the correct credential via the decryption_certificate or password property (depending on the encryption method used), or sets SkipThis to true.

The CertUsed parameter specifies the encryption method used. If set to true, it indicates that the document uses asymmetric (certificate-based) encryption. In that case, the IssuerRDN, SerialNumber, and SubjectKeyID parameters provide the details of the encryption certificate. Note that the document can be encrypted with more than one certificate (or have "more than one recipient"), in which case each certificate will invoke its own on_encrypted event loop.

CertUsed set to false indicates that the document uses password encryption. In this case, provide the password via the password property.

The NeedCredential parameter specifies whether the correct credential is already available to the class or still needs to be set. One example where NeedCredential would be set to false is where it had been provided by the application prior to processing the document (e.g. by setting the password property to a known pre-defined value). If NeedCredential is set to true, you must provide the valid credential for the decryption process to succeed.

on_error Event

Information about errors during signing/validation.

Syntax

class PDFDecryptorErrorEventParams(object):
  @property
  def error_code() -> int: ...

  @property
  def description() -> str: ...

# In class PDFDecryptor:
@property
def on_error() -> Callable[[PDFDecryptorErrorEventParams], None]: ...
@on_error.setter
def on_error(event_hook: Callable[[PDFDecryptorErrorEventParams], None]) -> None: ...

Remarks

The event is fired in case of exceptional conditions during PDF processing.

ErrorCode contains an error code and Description contains a textual description of the error.

on_external_decrypt Event

Handles remote or external decryption.

Syntax

class PDFDecryptorExternalDecryptEventParams(object):
  @property
  def operation_id() -> str: ...

  @property
  def algorithm() -> str: ...

  @property
  def pars() -> str: ...

  @property
  def encrypted_data() -> str: ...

  @property
  def data() -> str: ...
  @data.setter
  def data(value) -> None: ...

# In class PDFDecryptor:
@property
def on_external_decrypt() -> Callable[[PDFDecryptorExternalDecryptEventParams], None]: ...
@on_external_decrypt.setter
def on_external_decrypt(event_hook: Callable[[PDFDecryptorExternalDecryptEventParams], None]) -> None: ...

Remarks

Assign a handler to this event if you need to delegate a low-level decryption operation to an external, remote, or custom decryption engine. The handler receives an encrypted value in the EncryptedData parameter, and is expected to decrypt it and place the decrypted value into the Data parameter.

OperationId provides a comment about the operation and its origin. It depends on the exact class being used, and may be empty. Algorithm specifies the encryption algorithm being used, and Pars contains algorithm-dependent parameters.

The class uses base16 (hex) encoding for the EncryptedData, Data, and Pars parameters. If your decryption engine uses a different input and output encoding, you may need to decode and/or encode the data before and/or after the decryption.

Sample data encoded in base16: a0dee2a0382afbb09120ffa7ccd8a152 - lower case base16 A0DEE2A0382AFBB09120FFA7CCD8A152 - upper case base16

on_notification Event

This event notifies the application about an underlying control flow event.

Syntax

class PDFDecryptorNotificationEventParams(object):
  @property
  def event_id() -> str: ...

  @property
  def event_param() -> str: ...

# In class PDFDecryptor:
@property
def on_notification() -> Callable[[PDFDecryptorNotificationEventParams], None]: ...
@on_notification.setter
def on_notification(event_hook: Callable[[PDFDecryptorNotificationEventParams], None]) -> None: ...

Remarks

The class fires this event to let the application know about some event, occurrence, or milestone in the class. For example, it may fire to report completion of the document processing. The list of events being reported is not fixed, and may be flexibly extended over time.

The unique identifier of the event is provided in the EventID parameter. EventParam contains any parameters accompanying the occurrence. Depending on the type of the class, the exact action it is performing, or the document being processed, one or both may be omitted.

This class can fire this event with the following EventID values:

PDFDecryptor Config Settings

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the config method.

PDFDecryptor Config Settings

Base Config Settings

PDFDecryptor Errors

PDFDecryptor Errors