MessageEncryptor Class

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The MessageEncryptor class encrypts data and stores it in the PKCS#7 format.

Syntax

class secureblackbox.MessageEncryptor

Remarks

PKCS#7 (Public Key Cryptography Standard #7) is a common format used to store encrypted and signed data. It is used by a variety of protocols, including S/MIME and CMS.

MessageEncryptor can encrypt binary data into PKCS#7 EnvelopedData (asymmetric encryption) and EncryptedData (symmetric encryption) subformats. RSA and ECDH key wrapping and all popular symmetric encryption algorithms are supported.

Setting up and using MessageEncryptor is easy:

• Set up your source and destination via input_file (input_bytes) and output_file (output_bytes) properties.
• Set encryption_type as per the desired encryption type (asymmetric, symmetric, asymmetric with authentication).
• Set encryption_algorithm and, optionally, bits_in_key (if the encryption algorithm uses variable key lengths).
• For certificate-based (asymmetric) encryption, put the encryption certificate (or all of them, if there are more than one) to the encryption_certificates collection.
• For key-based (symmetric) encryption, assign the symmetric key to key property.
• Call encrypt to execute the operation.

Note that MessageEncryptor always produces binary PKCS#7-compliant encrypted messages. For S/MIME email encryption, see MailWriter. For PGP encryption, see PGPWriter. For raw symmetric encryption, see SymmetricCrypto. For XML-ENC encryption, see XMLEncryptor. MessageEncryptor encryptor = new MessageEncryptor(); // Set the encryption algorithm (default AES128) encryptor.setEncryptionAlgorithm("3DES"); // Select the file which contains the message that will be encrypted encryptor.setInputFile("decryptedMessage.txt"); // Select the file where the encrypted message will be written encryptor.setOutputFile("encryptedMessage.bin"); // We are using the public part of the certificate to encrypt data encryptor.setEncryptionCertificate(new Certificate("cert.cer")); encryptor.encrypt(); // Encrypt

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.

bits_in_key Property

The length of the encryption key.

Syntax

def get_bits_in_key() -> int: ...
def set_bits_in_key(value: int) -> None: ...

bits_in_key = property(get_bits_in_key, set_bits_in_key)

Default Value

0

Remarks

When using a variable-key encryption algorithm (typical examples are RC4, RC2, and Blowfish), provide the desired key length via this property.

This value is ignored if a fixed-key algorithm (such as AES128 or 3DES) is used.

encryption_algorithm Property

The symmetric key algorithm to use for encryption.

Syntax

def get_encryption_algorithm() -> str: ...
def set_encryption_algorithm(value: str) -> None: ...

encryption_algorithm = property(get_encryption_algorithm, set_encryption_algorithm)

Default Value

"AES128"

Remarks

Use this property to specify the symmetric algorithm to encrypt the data with.

encryption_cert_count Property

The number of records in the EncryptionCert arrays.

Syntax

def get_encryption_cert_count() -> int: ...
def set_encryption_cert_count(value: int) -> None: ...

encryption_cert_count = property(get_encryption_cert_count, set_encryption_cert_count)

Default Value

0

Remarks

This property controls the size of the following arrays:

• encryption_cert_bytes
• encryption_cert_handle

The array indices start at 0 and end at encryption_cert_count - 1.

encryption_cert_bytes Property

Returns the raw certificate data in DER format.

Syntax

def get_encryption_cert_bytes(encryption_cert_index: int) -> bytes: ...

Remarks

Returns the raw certificate data in DER format.

The encryption_cert_index parameter specifies the index of the item in the array. The size of the array is controlled by the encryption_cert_count property.

This property is read-only.

encryption_cert_handle Property

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

Syntax

def get_encryption_cert_handle(encryption_cert_index: int) -> int: ...
def set_encryption_cert_handle(encryption_cert_index: int, value: int) -> None: ...

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());

The encryption_cert_index parameter specifies the index of the item in the array. The size of the array is controlled by the encryption_cert_count property.

encryption_type Property

Specifies the kind of encrypted message to create.

Syntax

def get_encryption_type() -> int: ...
def set_encryption_type(value: int) -> None: ...

encryption_type = property(get_encryption_type, set_encryption_type)

Default Value

1

Remarks

Possible values:

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

A path to the source file.

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

Use this property to provide a path to the file containing the data to be encrypted.

key Property

The symmetric key to use for encryption.

Syntax

def get_key() -> bytes: ...
def set_key(value: bytes) -> None: ...

key = property(get_key, set_key)

Remarks

Use this property to provide a symmetric key to use for encryption. If the symmetric key is provided, an output message of EncryptedData type will be formed. The recipient of this message will need to have the same key to decrypt it.

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

A path to the output file.

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

Use this property to specify the file to save the encrypted message to.

signed_attribute_count Property

The number of records in the SignedAttribute arrays.

Syntax

def get_signed_attribute_count() -> int: ...
def set_signed_attribute_count(value: int) -> None: ...

signed_attribute_count = property(get_signed_attribute_count, set_signed_attribute_count)

Default Value

0

Remarks

This property controls the size of the following arrays:

• signed_attribute_oid
• signed_attribute_value

The array indices start at 0 and end at signed_attribute_count - 1.

signed_attribute_oid Property

The object identifier of the attribute.

Syntax

def get_signed_attribute_oid(signed_attribute_index: int) -> str: ...
def set_signed_attribute_oid(signed_attribute_index: int, value: str) -> None: ...

Default Value

""

Remarks

The object identifier of the attribute.

The signed_attribute_index parameter specifies the index of the item in the array. The size of the array is controlled by the signed_attribute_count property.

signed_attribute_value Property

The value of the attribute.

Syntax

def get_signed_attribute_value(signed_attribute_index: int) -> bytes: ...
def set_signed_attribute_value(signed_attribute_index: int, value: bytes) -> None: ...

Remarks

The value of the attribute.

The signed_attribute_index parameter specifies the index of the item in the array. The size of the array is controlled by the signed_attribute_count property.

unsigned_attribute_count Property

The number of records in the UnsignedAttribute arrays.

Syntax

def get_unsigned_attribute_count() -> int: ...
def set_unsigned_attribute_count(value: int) -> None: ...

unsigned_attribute_count = property(get_unsigned_attribute_count, set_unsigned_attribute_count)

Default Value

0

Remarks

This property controls the size of the following arrays:

• unsigned_attribute_oid
• unsigned_attribute_value

The array indices start at 0 and end at unsigned_attribute_count - 1.

unsigned_attribute_oid Property

The object identifier of the attribute.

Syntax

def get_unsigned_attribute_oid(unsigned_attribute_index: int) -> str: ...
def set_unsigned_attribute_oid(unsigned_attribute_index: int, value: str) -> None: ...

Default Value

""

Remarks

The object identifier of the attribute.

The unsigned_attribute_index parameter specifies the index of the item in the array. The size of the array is controlled by the unsigned_attribute_count property.

unsigned_attribute_value Property

The value of the attribute.

Syntax

def get_unsigned_attribute_value(unsigned_attribute_index: int) -> bytes: ...
def set_unsigned_attribute_value(unsigned_attribute_index: int, value: bytes) -> None: ...

Remarks

The value of the attribute.

The unsigned_attribute_index parameter specifies the index of the item in the array. The size of the array is controlled by the unsigned_attribute_count property.

add_attribute Method

Adds an attribute to the signature.

Syntax

def add_attribute(oid: str, value: bytes, signed_attribute: bool) -> int: ...

Remarks

Use this method to add a signed or unsigned attribute to the collection of attributes included in the new signature.

Note that CAdESSigner creates certain mandatory and/or widely used attributes automatically in accordance with requirements for a specific signing profile. For example, attributes such as SigningCertificateV2 or SigningTime are always added. Policy attributes are added if specified via the PolicyID or PolicyURI properties of the signature object.

Use the OID parameter to provide the object identifier of the attribute, in string form. For example, the OID for the SigningCertificateV2 attribute is 1.2.840.113549.1.9.16.2.47. The Value parameter should contain a well-formed, DER-encoded representation of the attribute value, in accordance with its specification.

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.

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:

encrypt Method

Encrypts data.

Syntax

def encrypt() -> None: ...

Remarks

This method encrypts the data provided via input_file or input_stream in accordance with PKCS#7 standard.

If encrypted with an encryption_certificate a message of EnvelopedData subtype is created. The private key that corresponds to the certificate is needed to decrypt the data.

If encrypted with key, a message of EncryptedData subtype is formed. The receiving party needs the same key as provided in key to decrypt the message.

reset Method

Resets the class settings.

Syntax

def reset() -> None: ...

Remarks

reset is a generic method available in every class.

on_error Event

Information about errors during PKCS#7 message encryption.

Syntax

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

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

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

Remarks

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

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Messages section.

on_notification Event

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

Syntax

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

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

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

MessageEncryptor 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.

MessageEncryptor Config Settings

Base Config Settings

MessageEncryptor Errors

MessageEncryptor Errors