SMIME Class

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The S/MIME class implements the S/MIME standard for encryption and decryption with public key cryptography and X.509 digital certificates.

Syntax

class ipworksencrypt.SMIME

Remarks

The S/MIME class implements the S/MIME V3 standard for encryption and decryption using Public Key Cryptography Standards (PKCS). In addition, the class can be used to both generate and verify RSA digital signatures. Using this class for decrypting or signing requires a valid digital certificate with a private key.

Before performing an operation the input and output values should be specified.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the input message (if any) will be read from input_message_headers or input_message_headers_string.

The headers of the resulting message will be available in the output_message_headers and output_message_headers_string properties.

Signing

To sign the current data included in the input message with a certificate, the certificate property must be set to a valid Certificate object for the signing certificate. The include_certificate and detached_signature properties allow you to specify additional details about the signing process. By setting include_certificate to True, digital certificates can be encoded and included in message signature when signing the document. Including a certificate is the preferred method of building signed messages. In addition the S/MIME class can also generate PKCS #7 formatted detached digital signatures and envelopes by specifying detached_signature.

Encrypting

To encrypt a message with the class in a PKCS envelope, you must first specify the Certificate for each recipient in the recipient_certs properties to encrypt the message with. You can easily add these with the add_recipient_cert method. Once you have done this you can call the encrypt method to encrypt the message with the recipient certificates.

In addition, the class allows you to sign and encrypt simultaneously with the sign_and_encrypt method. You must set all of the properties needed for both sign and encrypt

The result of the encrypted or signed data will be replaced in the output_message property and the output_message_headers property will be filled with the appropriate mime headers if applicable.

Decrypting

Decrypting PKCS envelopes is handled with the decrypt method. When this method is called, the class will attempt to find an appropriate certificate in the certificate property that matches the encrypting certificate. If it cannot find an appropriate certificate, an exception will be thrown and the message will not be decrypted.

Verifying Signatures

In addition, the S/MIME class can be used to verify signatures included in signed messages or documents. After specifying the input, verify_signature can then be used to verify the signature. If the message does not have a certificate attached, more then likely an exception will be thrown and the class will not be able to verify the signature. If verify_signature is successful, the signer_cert and signer_cert_chain properties will be filled with the certificate information of the message signer. This information can be used to verify the signing certificates.

Similar to sign_and_encrypt, decrypt_and_verify_signature can be used to both decrypt and verify the message in message.

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.

cert_encoded Property

This is the certificate (PEM/Base64 encoded).

Syntax

def get_cert_encoded() -> bytes: ...
def set_cert_encoded(value: bytes) -> None: ...

cert_encoded = property(get_cert_encoded, set_cert_encoded)

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The cert_store and cert_subject properties also may be used to specify a certificate.

When cert_encoded is set, a search is initiated in the current cert_store for the private key of the certificate. If the key is found, cert_subject is updated to reflect the full subject of the selected certificate; otherwise, cert_subject is set to an empty string.

cert_store Property

This is the name of the certificate store for the client certificate.

Syntax

def get_cert_store() -> bytes: ...
def set_cert_store(value: bytes) -> None: ...

cert_store = property(get_cert_store, set_cert_store)

Default Value

"MY"

Remarks

This is the name of the certificate store for the client certificate.

The cert_store_type property denotes the type of the certificate store specified by cert_store. If the store is password protected, specify the password in cert_store_password.

cert_store is used in conjunction with the cert_subject property to specify client certificates. If cert_store has a value, and cert_subject or cert_encoded is set, a search for a certificate is initiated. Please see the cert_subject property for details.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

When the certificate store type is PFXFile, this property must be set to the name of the file. When the type is PFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

cert_store_password Property

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Syntax

def get_cert_store_password() -> str: ...
def set_cert_store_password(value: str) -> None: ...

cert_store_password = property(get_cert_store_password, set_cert_store_password)

Default Value

""

Remarks

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

cert_store_type Property

This is the type of certificate store for this certificate.

Syntax

def get_cert_store_type() -> int: ...
def set_cert_store_type(value: int) -> None: ...

cert_store_type = property(get_cert_store_type, set_cert_store_type)

Default Value

0

Remarks

This is the type of certificate store for this certificate.

The class supports both public and private keys in a variety of formats. When the cstAuto value is used, the class will automatically determine the type. This property can take one of the following values:

cert_subject Property

This is the subject of the certificate used for client authentication.

Syntax

def get_cert_subject() -> str: ...
def set_cert_subject(value: str) -> None: ...

cert_subject = property(get_cert_subject, set_cert_subject)

Default Value

""

Remarks

This is the subject of the certificate used for client authentication.

This property must be set after all other certificate properties are set. When this property is set, a search is performed in the current certificate store to locate a certificate with a matching subject.

If a matching certificate is found, the property is set to the full subject of the matching certificate.

If an exact match is not found, the store is searched for subjects containing the value of the property.

If a match is still not found, the property is set to an empty string, and no certificate is selected.

The special value "*" picks a random certificate in the certificate store.

The certificate subject is a comma-separated list of distinguished name fields and values. For instance, "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are as follows:

If a field value contains a comma, it must be quoted.

detached_signature Property

This property specifies whether to include a detached signature when signing a message.

Syntax

def get_detached_signature() -> bool: ...
def set_detached_signature(value: bool) -> None: ...

detached_signature = property(get_detached_signature, set_detached_signature)

Default Value

TRUE

Remarks

This property specifies whether to include a detached signature when signing a message. If the value of this property is True, message will be encoded as a multipart/signed MIME message with a detached signature when calling sign. This will create a message with two MIME parts, one with the contents of message, and another with the detached signature.

If this property is False, the current contents of message will be PKCS encoded and included with the signature in message. This will create a single-part message with no MIME boundaries.

encrypting_algorithm Property

The property includes textual description of the encrypting algorithm.

Syntax

def get_encrypting_algorithm() -> str: ...
def set_encrypting_algorithm(value: str) -> None: ...

encrypting_algorithm = property(get_encrypting_algorithm, set_encrypting_algorithm)

Default Value

"3DES"

Remarks

This property contains either the name of the algorithm (such as 3DES or AES), or an object identifier (OID) string representing the algorithm.

Possible values are as follows:

• "3DES"
• "DES"
• "RC2CBC40"
• "RC2CBC64"
• "RC2CBC128" or "RC2"
• "AESCBC128" or "AES"
• "AESCBC192"
• "AESCBC256"
• "AESGCM128" or "AESGCM"
• "AESGCM192"
• "AESGCM256"

include_certificate Property

This property specifies whether to include the signer's certificate with the signed message.

Syntax

def get_include_certificate() -> bool: ...
def set_include_certificate(value: bool) -> None: ...

include_certificate = property(get_include_certificate, set_include_certificate)

Default Value

TRUE

Remarks

If this property is set to True, the certificate used to sign the message will be encoded and included in a message signature when calling sign or sign_and_encrypt.

Including a certificate is the preferred method of building signed messages. If you do not include a certificate, the message recipient may not be able to verify the sender's signature.

include_chain Property

This property specifies whether to include the signer's certificate chain with the signed message.

Syntax

def get_include_chain() -> bool: ...
def set_include_chain(value: bool) -> None: ...

include_chain = property(get_include_chain, set_include_chain)

Default Value

FALSE

Remarks

If this property is set to True, the entire certificate's chain that was used to sign the message will be encoded and included in the message signature when calling sign or sign_and_encrypt.

Note: To include the chain, the include_certificate property must also be set to true.

include_headers Property

This property tells the class whether to include the headers when encoding the message.

Syntax

def get_include_headers() -> bool: ...
def set_include_headers(value: bool) -> None: ...

include_headers = property(get_include_headers, set_include_headers)

Default Value

FALSE

Remarks

If True, the class will include the headers when sign, encrypt, or sign_and_encrypt are called. If False, only the message will be encoded.

The default value for include_headers is False.

input_file Property

This property includes the file to process.

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

This property specifies the file to be processed. Set this property to the full or relative path to the file that will be processed.

Encrypt and/or Sign

When encrypting or signing, this may be set to a file containing content that will be encrypted and/or signed.

Decrypt and/or Verify

When decrypting or verifying a signature, this may be set to a file containing the fully encoded S/MIME message.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the input message (if any) will be read from input_message_headers or input_message_headers_string.

input_message Property

This property includes the message to process.

Syntax

def get_input_message() -> bytes: ...
def set_input_message(value: bytes) -> None: ...

input_message = property(get_input_message, set_input_message)

Default Value

""

Remarks

This property specifies the message to be processed.

Encrypt and/or Sign

When encrypting or signing, this may be set to the content that will be encrypted and/or signed.

Decrypt and/or Verify

When decrypting or verifying a signature, this may be set to the fully encoded S/MIME message.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the input message (if any) will be read from input_message_headers or input_message_headers_string.

input_message_header_count Property

The number of records in the InputMessageHeader arrays.

Syntax

def get_input_message_header_count() -> int: ...
def set_input_message_header_count(value: int) -> None: ...

input_message_header_count = property(get_input_message_header_count, set_input_message_header_count)

Default Value

0

Remarks

This property controls the size of the following arrays:

• input_message_header_field
• input_message_header_value

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

input_message_header_field Property

This property contains the name of the HTTP header (this is the same case as it is delivered).

Syntax

def get_input_message_header_field(input_message_header_index: int) -> str: ...
def set_input_message_header_field(input_message_header_index: int, value: str) -> None: ...

Default Value

""

Remarks

This property contains the name of the HTTP Header (this is the same case as it is delivered).

The input_message_header_index parameter specifies the index of the item in the array. The size of the array is controlled by the input_message_header_count property.

input_message_header_value Property

This property contains the header contents.

Syntax

def get_input_message_header_value(input_message_header_index: int) -> str: ...
def set_input_message_header_value(input_message_header_index: int, value: str) -> None: ...

Default Value

""

Remarks

This property contains the Header contents.

The input_message_header_index parameter specifies the index of the item in the array. The size of the array is controlled by the input_message_header_count property.

input_message_headers_string Property

This property includes the string version of headers from the S/MIME message.

Syntax

def get_input_message_headers_string() -> str: ...
def set_input_message_headers_string(value: str) -> None: ...

input_message_headers_string = property(get_input_message_headers_string, set_input_message_headers_string)

Default Value

""

Remarks

This property contains the string version of headers from the S/MIME message.

This property may be set to the headers of the message that will be decrypted/verified.

internal_headers Property

This property includes the headers of the MIME entity inside the encrypted or signed message.

Syntax

def get_internal_headers() -> str: ...
def set_internal_headers(value: str) -> None: ...

internal_headers = property(get_internal_headers, set_internal_headers)

Default Value

""

Remarks

After an encryption, decryption, signing, or verification operation is completed, this property shows the headers of the encrypted or signed message part.

message_encrypted Property

This property specifies whether or not the current message is encrypted.

Syntax

def get_message_encrypted() -> bool: ...

message_encrypted = property(get_message_encrypted, None)

Default Value

FALSE

Remarks

This property indicates whether or not the current message is encrypted. This property will return True if the current message appears to be encrypted, according to the value of message_headers.

This property is read-only.

message_signed Property

This property specifies whether or not the current message is signed.

Syntax

def get_message_signed() -> bool: ...

message_signed = property(get_message_signed, None)

Default Value

FALSE

Remarks

This property indicates whether or not the current message is signed. This property will return True if the current message appears to be signed, according to the value of message_headers.

Note: A message that is both signed and encrypted will not appear to be signed until after it is decrypted.

This property is read-only.

output_file Property

This property specifies 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

This property specifies the file to which the output will be written. This may be set to an absolute or relative path.

Encrypt and/or Sign

When encrypting or signing, this specifies a file where the fully encoded S/MIME message will be written.

Decrypt and/or Verify

When decrypting or verifying a signature, this specifies a file where the decrypted/verified content will be written.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the resulting message will be available in the output_message_headers and output_message_headers_string properties.

output_message Property

This property includes the output message after processing.

Syntax

def get_output_message() -> bytes: ...

output_message = property(get_output_message, None)

Default Value

""

Remarks

This property will be populated with the output of the operation if output_file is not set.

Encrypt and/or Sign

When encrypting or signing, this will hold the fully encoded S/MIME message.

Decrypt and/or Verify

When decrypting or verifying a signature, this will hold the decrypted/verified content.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the resulting message will be available in the output_message_headers and output_message_headers_string properties.

This property is read-only.

output_message_header_count Property

The number of records in the OutputMessageHeader arrays.

Syntax

def get_output_message_header_count() -> int: ...

output_message_header_count = property(get_output_message_header_count, None)

Default Value

0

Remarks

This property controls the size of the following arrays:

• output_message_header_field
• output_message_header_value

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

This property is read-only.

output_message_header_field Property

This property contains the name of the HTTP header (this is the same case as it is delivered).

Syntax

def get_output_message_header_field(output_message_header_index: int) -> str: ...

Default Value

""

Remarks

This property contains the name of the HTTP Header (this is the same case as it is delivered).

The output_message_header_index parameter specifies the index of the item in the array. The size of the array is controlled by the output_message_header_count property.

This property is read-only.

output_message_header_value Property

This property contains the header contents.

Syntax

def get_output_message_header_value(output_message_header_index: int) -> str: ...

Default Value

""

Remarks

This property contains the Header contents.

The output_message_header_index parameter specifies the index of the item in the array. The size of the array is controlled by the output_message_header_count property.

This property is read-only.

output_message_headers_string Property

This property includes a string version of headers from the S/MIME message.

Syntax

def get_output_message_headers_string() -> str: ...

output_message_headers_string = property(get_output_message_headers_string, None)

Default Value

""

Remarks

This property contains the string version of headers from the S/MIME message. The class will populate this property after signing and/or encrypting.

The user should use these additional headers when emailing or sending the output_message. This can be done by including these headers in the OtherHeaders property of the class that you wish to send the message with.

After the decryption or verification, this property contains the headers of the verified or decrypted message.

This property is read-only.

overwrite Property

This property indicates whether or not the class should overwrite files.

Syntax

def get_overwrite() -> bool: ...
def set_overwrite(value: bool) -> None: ...

overwrite = property(get_overwrite, set_overwrite)

Default Value

TRUE

Remarks

This property indicates whether or not the class will overwrite output_file. If overwrite is False, an error will be thrown whenever output_file exists before an operation. The default value is False.

recipient_cert_count Property

The number of records in the RecipientCert arrays.

Syntax

def get_recipient_cert_count() -> int: ...
def set_recipient_cert_count(value: int) -> None: ...

recipient_cert_count = property(get_recipient_cert_count, set_recipient_cert_count)

Default Value

0

Remarks

This property controls the size of the following arrays:

• recipient_cert_encoded
• recipient_cert_store
• recipient_cert_store_password
• recipient_cert_store_type
• recipient_cert_subject

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

recipient_cert_encoded Property

This is the certificate (PEM/Base64 encoded).

Syntax

def get_recipient_cert_encoded(recipient_cert_index: int) -> bytes: ...
def set_recipient_cert_encoded(recipient_cert_index: int, value: bytes) -> None: ...

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The recipient_cert_store and recipient_cert_subject properties also may be used to specify a certificate.

When recipient_cert_encoded is set, a search is initiated in the current recipient_cert_store for the private key of the certificate. If the key is found, recipient_cert_subject is updated to reflect the full subject of the selected certificate; otherwise, recipient_cert_subject is set to an empty string.

The recipient_cert_index parameter specifies the index of the item in the array. The size of the array is controlled by the recipient_cert_count property.

recipient_cert_store Property

This is the name of the certificate store for the client certificate.

Syntax

def get_recipient_cert_store(recipient_cert_index: int) -> bytes: ...
def set_recipient_cert_store(recipient_cert_index: int, value: bytes) -> None: ...

Default Value

"MY"

Remarks

This is the name of the certificate store for the client certificate.

The recipient_cert_store_type property denotes the type of the certificate store specified by recipient_cert_store. If the store is password protected, specify the password in recipient_cert_store_password.

recipient_cert_store is used in conjunction with the recipient_cert_subject property to specify client certificates. If recipient_cert_store has a value, and recipient_cert_subject or recipient_cert_encoded is set, a search for a certificate is initiated. Please see the recipient_cert_subject property for details.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

When the certificate store type is PFXFile, this property must be set to the name of the file. When the type is PFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

The recipient_cert_index parameter specifies the index of the item in the array. The size of the array is controlled by the recipient_cert_count property.

recipient_cert_store_password Property

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Syntax

def get_recipient_cert_store_password(recipient_cert_index: int) -> str: ...
def set_recipient_cert_store_password(recipient_cert_index: int, value: str) -> None: ...

Default Value

""

Remarks

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

The recipient_cert_index parameter specifies the index of the item in the array. The size of the array is controlled by the recipient_cert_count property.

recipient_cert_store_type Property

This is the type of certificate store for this certificate.

Syntax

def get_recipient_cert_store_type(recipient_cert_index: int) -> int: ...
def set_recipient_cert_store_type(recipient_cert_index: int, value: int) -> None: ...

Default Value

0

Remarks

This is the type of certificate store for this certificate.

The class supports both public and private keys in a variety of formats. When the cstAuto value is used, the class will automatically determine the type. This property can take one of the following values:

The recipient_cert_index parameter specifies the index of the item in the array. The size of the array is controlled by the recipient_cert_count property.

recipient_cert_subject Property

This is the subject of the certificate used for client authentication.

Syntax

def get_recipient_cert_subject(recipient_cert_index: int) -> str: ...
def set_recipient_cert_subject(recipient_cert_index: int, value: str) -> None: ...

Default Value

""

Remarks

This is the subject of the certificate used for client authentication.

This property must be set after all other certificate properties are set. When this property is set, a search is performed in the current certificate store to locate a certificate with a matching subject.

If a matching certificate is found, the property is set to the full subject of the matching certificate.

If an exact match is not found, the store is searched for subjects containing the value of the property.

If a match is still not found, the property is set to an empty string, and no certificate is selected.

The special value "*" picks a random certificate in the certificate store.

The certificate subject is a comma-separated list of distinguished name fields and values. For instance, "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are as follows:

If a field value contains a comma, it must be quoted.

The recipient_cert_index parameter specifies the index of the item in the array. The size of the array is controlled by the recipient_cert_count property.

signer_cert_encoded Property

This is the certificate (PEM/Base64 encoded).

Syntax

def get_signer_cert_encoded() -> bytes: ...
def set_signer_cert_encoded(value: bytes) -> None: ...

signer_cert_encoded = property(get_signer_cert_encoded, set_signer_cert_encoded)

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The signer_cert_store and signer_cert_subject properties also may be used to specify a certificate.

When signer_cert_encoded is set, a search is initiated in the current signer_cert_store for the private key of the certificate. If the key is found, signer_cert_subject is updated to reflect the full subject of the selected certificate; otherwise, signer_cert_subject is set to an empty string.

signer_cert_issuer Property

This is the issuer of the certificate.

Syntax

def get_signer_cert_issuer() -> str: ...

signer_cert_issuer = property(get_signer_cert_issuer, None)

Default Value

""

Remarks

This is the issuer of the certificate. This property contains a string representation of the name of the issuing authority for the certificate.

This property is read-only.

signer_cert_serial_number Property

This is the serial number of the certificate encoded as a string.

Syntax

def get_signer_cert_serial_number() -> str: ...

signer_cert_serial_number = property(get_signer_cert_serial_number, None)

Default Value

""

Remarks

This is the serial number of the certificate encoded as a string. The number is encoded as a series of hexadecimal digits, with each pair representing a byte of the serial number.

This property is read-only.

signer_cert_store Property

This is the name of the certificate store for the client certificate.

Syntax

def get_signer_cert_store() -> bytes: ...
def set_signer_cert_store(value: bytes) -> None: ...

signer_cert_store = property(get_signer_cert_store, set_signer_cert_store)

Default Value

"MY"

Remarks

This is the name of the certificate store for the client certificate.

The signer_cert_store_type property denotes the type of the certificate store specified by signer_cert_store. If the store is password protected, specify the password in signer_cert_store_password.

signer_cert_store is used in conjunction with the signer_cert_subject property to specify client certificates. If signer_cert_store has a value, and signer_cert_subject or signer_cert_encoded is set, a search for a certificate is initiated. Please see the signer_cert_subject property for details.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

When the certificate store type is PFXFile, this property must be set to the name of the file. When the type is PFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

signer_cert_store_password Property

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Syntax

def get_signer_cert_store_password() -> str: ...
def set_signer_cert_store_password(value: str) -> None: ...

signer_cert_store_password = property(get_signer_cert_store_password, set_signer_cert_store_password)

Default Value

""

Remarks

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

signer_cert_store_type Property

This is the type of certificate store for this certificate.

Syntax

def get_signer_cert_store_type() -> int: ...
def set_signer_cert_store_type(value: int) -> None: ...

signer_cert_store_type = property(get_signer_cert_store_type, set_signer_cert_store_type)

Default Value

0

Remarks

This is the type of certificate store for this certificate.

The class supports both public and private keys in a variety of formats. When the cstAuto value is used, the class will automatically determine the type. This property can take one of the following values:

signer_cert_subject Property

This is the subject of the certificate used for client authentication.

Syntax

def get_signer_cert_subject() -> str: ...
def set_signer_cert_subject(value: str) -> None: ...

signer_cert_subject = property(get_signer_cert_subject, set_signer_cert_subject)

Default Value

""

Remarks

This is the subject of the certificate used for client authentication.

This property must be set after all other certificate properties are set. When this property is set, a search is performed in the current certificate store to locate a certificate with a matching subject.

If a matching certificate is found, the property is set to the full subject of the matching certificate.

If an exact match is not found, the store is searched for subjects containing the value of the property.

If a match is still not found, the property is set to an empty string, and no certificate is selected.

The special value "*" picks a random certificate in the certificate store.

The certificate subject is a comma-separated list of distinguished name fields and values. For instance, "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are as follows:

If a field value contains a comma, it must be quoted.

signer_cert_chain_count Property

The number of records in the SignerCertChain arrays.

Syntax

def get_signer_cert_chain_count() -> int: ...

signer_cert_chain_count = property(get_signer_cert_chain_count, None)

Default Value

0

Remarks

This property controls the size of the following arrays:

• signer_cert_chain_encoded

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

This property is read-only.

signer_cert_chain_encoded Property

This is the certificate (PEM/Base64 encoded).

Syntax

def get_signer_cert_chain_encoded(signer_cert_chain_index: int) -> bytes: ...

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The signer_cert_chain_store and signer_cert_chain_subject properties also may be used to specify a certificate.

When signer_cert_chain_encoded is set, a search is initiated in the current signer_cert_chain_store for the private key of the certificate. If the key is found, signer_cert_chain_subject is updated to reflect the full subject of the selected certificate; otherwise, signer_cert_chain_subject is set to an empty string.

The signer_cert_chain_index parameter specifies the index of the item in the array. The size of the array is controlled by the signer_cert_chain_count property.

This property is read-only.

signing_algorithm Property

This property includes a textual description of the signature hash algorithm.

Syntax

def get_signing_algorithm() -> str: ...
def set_signing_algorithm(value: str) -> None: ...

signing_algorithm = property(get_signing_algorithm, set_signing_algorithm)

Default Value

"SHA256"

Remarks

This property specifies the hash algorithm used to prepare the message digest for signature.

This property must contain either the name of the algorithm (such as MD5 or SHA1), or an object Id (OID) string representing the hash algorithm. Possible values are as follows:

• sha1
• md5
• sha-256 (default)
• sha-384
• sha-512
• sha-224

When read, the value of the property always contains the OID of the algorithm, or an empty string if the algorithm is unknown.

use_oaep Property

This property specifies whether or not to use Optimal Asymmetric Encryption Padding (OAEP).

Syntax

def get_use_oaep() -> bool: ...
def set_use_oaep(value: bool) -> None: ...

use_oaep = property(get_use_oaep, set_use_oaep)

Default Value

FALSE

Remarks

This property specifies whether or not to use Optimal Asymmetric Encryption Padding (OAEP). By default, this value is False and the class will use PKCS1.

To specify nondefault OAEP options, please see OAEPRSAHashAlgorithm, OAEPMGF1HashAlgorithm, and OAEPParams

use_pss Property

This property specifies whether or not RSA-PSS will be used during signing and verification.

Syntax

def get_use_pss() -> bool: ...
def set_use_pss(value: bool) -> None: ...

use_pss = property(get_use_pss, set_use_pss)

Default Value

FALSE

Remarks

This property specifies whether or not RSA-PSS will be used when signing and verifying messages. The default value is False.

add_recipient_cert Method

This method is used to add recipient certificates used to encrypt messages.

Syntax

def add_recipient_cert(cert_encoded: bytes) -> None: ...

Remarks

This method is used to add recipient certificates to the internal message_recipients properties used to encrypt the message. The recipient certificate must be a valid PKCS-encoded certificate. If the certificate provided is Base64 encoded, it will be decoded first by the object.

The CertMgr class may be used to retrieve the appropriate certificate from the system.

check_message_encrypted Method

This method checks whether or not the current message is encrypted.

Syntax

def check_message_encrypted() -> bool: ...

Remarks

This method is used to check whether or not the current message is encrypted. This method will return True, if the current message appears to be encrypted, according to the value of output_message_headers.

check_message_signed Method

This method checks whether or not the current message is signed.

Syntax

def check_message_signed() -> bool: ...

Remarks

This method is used to check whether or not the current message is signed. This method will return True, if the current message appears to be signed, according to the value of output_message_headers.

Note: A message that is both signed and encrypted will not appear to be signed until after it is decrypted.

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

This method decrypts the current Message .

Syntax

def decrypt() -> None: ...

Remarks

This method takes attempts to decrypt the encrypted message using the certificate in certificate.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the input message (if any) will be read from input_message_headers or input_message_headers_string.

The headers of the resulting message will be available in the output_message_headers and output_message_headers_string properties.

decrypt_and_verify_signature Method

This method decrypts and verifies the signature of the current message.

Syntax

def decrypt_and_verify_signature() -> None: ...

Remarks

This method attempts to both decrypt and verify the signature of the message. All of the properties affected by calling the decrypt and verify_signature methods are affected in the same manner.

Note: This function does not attempt to check the validity of the signing certificate.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the input message (if any) will be read from input_message_headers or input_message_headers_string.

The headers of the resulting message will be available in the output_message_headers and output_message_headers_string properties.

encrypt Method

This method encrypts the message.

Syntax

def encrypt() -> None: ...

Remarks

This method encrypts the data specified in input_file or input_message in a PKCS-encoded envelope with all of the recipient certificates specified in the message_recipients properties.

The result of the encrypted data will be written to output_file, or output_message. The output_message_headers property will be filled with the required S/MIME headers.

Note: The message headers, including the Sender, Recipient(s), and Subject, are not encrypted. If this is sensitive information, consider including these headers in the message body as a MIME entity and providing other headers for the S/MIME wrapper.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the input message (if any) will be read from input_message_headers or input_message_headers_string.

The headers of the resulting message will be available in the output_message_headers and output_message_headers_string properties.

get_recipient_info Method

This method gets the recipient information for an encrypted message.

Syntax

def get_recipient_info() -> None: ...

Remarks

This method will fire a on_recipient_info event for every recipient certificate for which the message has been encrypted. The event will contain information about the Issuer and the SerialNumber for each recipient of the message.

get_signer_cert_info Method

This method gets the signature information for an signed message.

Syntax

def get_signer_cert_info() -> None: ...

Remarks

This method retrieves information about the certificate used to sign the message. This may be called before calling verify_signature to determine which certificate should be loaded for verification.

When this method is called, the on_signer_cert_info event fires once for each signer of the message. Use the parameters of the on_signer_cert_info to determine which certificate to specify before calling verify_signature.

Note: Use of this method is optional. If no certificate is specified before calling verify_signature, the class will fire the on_signer_cert_info and a certificate may be loaded from within the event at that time (if necessary).

reset Method

This method resets the class properties.

Syntax

def reset() -> None: ...

Remarks

This method resets the values of all message and certificate properties. It is an easy way to reset the class properties before starting to populate with new values.

sign Method

This method signs the current message.

Syntax

def sign() -> None: ...

Remarks

This method digitally signs the input data with the the certificate provided. Certificates are provided by specifying the certificate property. The include_certificate and detached_signature properties allow you to specify addition details about what to include when signing the message.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the input message (if any) will be read from input_message_headers or input_message_headers_string.

The headers of the resulting message will be available in the output_message_headers and output_message_headers_string properties.

sign_and_encrypt Method

This method signs and encrypts the current message.

Syntax

def sign_and_encrypt() -> None: ...

Remarks

This method both signs and encrypts the input message into a single PKCS-encoded envelope. The value in detached_signature is ignored: the class will always generate an attached signature when calling this method. All other properties used by calling the sign and encrypt methods are used in the same manner.

Note: The message headers, including the Sender, Recipient(s), and Subject, are not encrypted. If this is sensitive information, consider including these headers in the message body as a MIME entity and providing other headers for the S/MIME wrapper.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the input message (if any) will be read from input_message_headers or input_message_headers_string.

The headers of the resulting message will be available in the output_message_headers and output_message_headers_string properties.

verify_signature Method

This method verifies the signature of the current message.

Syntax

def verify_signature() -> None: ...

Remarks

This method attempts to verify the signature of the input message. If the message does not have a certificate attached, the class will attempt to verify the signature using the certificate supplied in signer_cert (if any). If no certificate is found, the class fails with an error.

If this method is successful, the signer_cert property will contain the certificate information of the message signer.

Note: This function does not attempt to check the validity of the signing certificate.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• input_file
• input_message

When a valid source is found the search stops. The order in which the output properties are checked is as follows:

• output_file
• output_message: The output data is written to this property if no other destination is specified.

The headers of the input message (if any) will be read from input_message_headers or input_message_headers_string.

The headers of the resulting message will be available in the output_message_headers and output_message_headers_string properties.

on_error Event

Fired when information is available about errors during data delivery.

Syntax

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

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

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

Remarks

The on_error event is fired in case of exceptional conditions during message processing. Normally the class fails with an error.

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

on_recipient_info Event

This event is fired for each recipient certificate of the encrypted message.

Syntax

class SMIMERecipientInfoEventParams(object):
  @property
  def issuer() -> str: ...

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

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

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

# In class SMIME:
@property
def on_recipient_info() -> Callable[[SMIMERecipientInfoEventParams], None]: ...
@on_recipient_info.setter
def on_recipient_info(event_hook: Callable[[SMIMERecipientInfoEventParams], None]) -> None: ...

Remarks

When get_recipient_info is called on a valid encrypted message, this event will fire once for each recipient certificate that the message has been encrypted for. This may be used to identify the certificate to load.

Issuer is the subject of the issuer certificate.

SerialNumber is the serial number of the encryption certificate.

SubjectKeyIdentifier is the X.509 subjectKeyIdentifier extension value of the certificate used to sign the message encoded as a hex string.

EncryptionAlgorithm is the encryption algorithm used to encrypt the message. Possible values are as follows:

• "3DES"
• "DES"
• "RC2CBC40"
• "RC2CBC64"
• "RC2CBC128" or "RC2"
• "AESCBC128" or "AES"
• "AESCBC192"
• "AESCBC256"
• "AESGCM128" or "AESGCM"
• "AESGCM192"
• "AESGCM256"

on_signer_cert_info Event

This event is fired during verification of the signed message.

Syntax

class SMIMESignerCertInfoEventParams(object):
  @property
  def issuer() -> str: ...

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

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

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

# In class SMIME:
@property
def on_signer_cert_info() -> Callable[[SMIMESignerCertInfoEventParams], None]: ...
@on_signer_cert_info.setter
def on_signer_cert_info(event_hook: Callable[[SMIMESignerCertInfoEventParams], None]) -> None: ...

Remarks

During verification, this event will be raised while parsing the signer's certificate information. The parameters that are populated depend on the options used when the message was originally signed. This information may be used to select the correct certificate for signer_cert to verify the signature. The following parameters may be populated:

Issuer specifies the subject of the issuer of the certificate used to sign the message.

SerialNumber is the serial number of the certificate used to sign the message.

SubjectKeyIdentifier is the X.509 subjectKeyIdentifier extension value of the certificate used to sign the message encoded as a hex string.

CertEncoded is the PEM (Base64 encoded) public certificate needed to verify the signature.

Note: When this value is present, the class will automatically use this value to perform signature verification.

The signer_cert property may be set from within this event. In this manner, the decision of which signer certificate to load may be delayed until the parameters of this event are inspected and the correct certificate can be located and loaded.

SMIME 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.

SMIME Config Settings

Base Config Settings

SMIME Errors

SMIME Errors

	10191   Invalid index (RecipientIndex).
	10192   Message decoding error (code).
	10193   Unexpected message type.
	10194   Unsupported hashing/signing algorithm.
	10195   The message does not have any signers.
	10196   The message signature could not be verified.
	10197   Could not locate a suitable decryption certificate.
	10198   The signer certificate could not be found.
	10199   No signing certificate was supplied for signing the message.
	10201   The specified certificate was not the one required.
	10202   The specified certificate could not be found.
	10221   Could not acquire CSP.
	10222   Type validation error.
	10223   Unsupported key size.
	10224   Unrecognized Content-Type object identifier.
	10225   Unrecognized public key format.
	10226   No choices specified.
	10228   Must specify output stream.
	10280   Invalid part index.
	10281   Unknown MIME type.
	10283   No MIME-boundary found.
	10280   Error decoding certificate.