RSA Class

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Implements RSA public-key cryptography to encrypt/decrypt and sign/verify messages.

Syntax

class ipworksencrypt.RSA

Remarks

The RSA class implements RSA public-key cryptography to encrypt/decrypt messages and sign/verify hash signatures.

To begin you must either specify an existing key or create a new key. Existing private keys may be specified by setting the Key* properties. To create a new key call create_key. Alternatively an existing certificate may be specified by setting the Certificate* properties

Signing

To sign data first set key or certificate. Specify the input data using input_file or input_message. Next call sign. The class will populate hash_value and hash_signature. After calling sign the public key must be sent to the recipient along with hash_signature.

Encrypting

To encrypt data set recipient_key or recipient_cert. Specify the input data using input_file or input_message. Next call encrypt. The class will populate output_message, or write to the file specified by output_file.

Signature Verification

To verify a signature specify the input data using input_file or input_message. Set signer_key or signer_cert. Next set hash_signature and call verify_signature. The verify_signature method will return True if the signature was successfully verified.

Decrypting

To decrypt data first set key or certificate. Specify the input data using input_file or input_message. Next call decrypt. The class will populate output_message, or write to the file specified by output_file.

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.

RSA Keys

A RSA key is made up of a number of individual parameters.

The public key consists of the following parameters:

• key_modulus
• key_exponent

The class also includes the key_public_key property which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both sides of the encryption/signing and decryption/signature verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in key_public_key in which case the individual parameters must be sent.

The private key may be represented in one of two ways. Both are mathematically equivalent. Private key format 1:

• key_modulus
• keyp
• keyq
• key_dp
• key_dq

Private key format 2 is simpler but has decreased performance when decrypting and signing. This format is:

• key_modulus
• keyd

The class also include the key_private_key property which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

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 are designations of 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. PKCS12 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 displayed below.

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

hash_algorithm Property

The hash algorithm used for signing and signature verification.

Syntax

def get_hash_algorithm() -> int: ...
def set_hash_algorithm(value: int) -> None: ...

hash_algorithm = property(get_hash_algorithm, set_hash_algorithm)

Default Value

2

Remarks

This property specifies the hash algorithm used for signing and signature verification. Possible values are:

hash_signature Property

The hash signature.

Syntax

def get_hash_signature() -> bytes: ...
def set_hash_signature(value: bytes) -> None: ...

hash_signature = property(get_hash_signature, set_hash_signature)

Default Value

""

Remarks

This property holds the computed hash signature. This is populated after calling sign. This must be set before calling verify_signature.

hash_value Property

The hash value of the data.

Syntax

def get_hash_value() -> bytes: ...
def set_hash_value(value: bytes) -> None: ...

hash_value = property(get_hash_value, set_hash_value)

Default Value

""

Remarks

This property holds the computed hash value for the specified data. This is populated when calling sign or verify_signature when an input file is specified by setting input_file or input_message.

If you know the hash value prior to using the class you may specify the pre-computed hash value here.

Hash Notes

The class will determine whether or not to recompute the hash based on the properties that are set. If a file is specified by input_file or input_message the hash will be recomputed when calling sign or verify_signature. If the hash_value property is set the class will only sign the hash or verify the hash signature. Setting input_file or input_message clears the hash_value property. Setting the hash_value property clears the input file selection.

input_file Property

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 which will be processed.

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.

input_message Property

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.

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.

keyd Property

Represents the D parameter for the RSA algorithm.

Syntax

def get_keyd() -> bytes: ...
def set_keyd(value: bytes) -> None: ...

keyd = property(get_keyd, set_keyd)

Default Value

""

Remarks

Represents the D parameter for the RSA algorithm.

key_dp Property

Represents the DP parameter for the RSA algorithm.

Syntax

def get_key_dp() -> bytes: ...
def set_key_dp(value: bytes) -> None: ...

key_dp = property(get_key_dp, set_key_dp)

Default Value

""

Remarks

Represents the DP parameter for the RSA algorithm.

key_dq Property

Represents the DQ parameter for the RSA algorithm.

Syntax

def get_key_dq() -> bytes: ...
def set_key_dq(value: bytes) -> None: ...

key_dq = property(get_key_dq, set_key_dq)

Default Value

""

Remarks

Represents the DQ parameter for the RSA algorithm.

key_exponent Property

Represents the Exponent parameter for the RSA algorithm.

Syntax

def get_key_exponent() -> bytes: ...
def set_key_exponent(value: bytes) -> None: ...

key_exponent = property(get_key_exponent, set_key_exponent)

Default Value

""

Remarks

Represents the Exponent parameter for the RSA algorithm.

key_inverseq Property

Represents the InverseQ parameter for the RSA algorithm.

Syntax

def get_key_inverseq() -> bytes: ...
def set_key_inverseq(value: bytes) -> None: ...

key_inverseq = property(get_key_inverseq, set_key_inverseq)

Default Value

""

Remarks

Represents the InverseQ parameter for the RSA algorithm. This parameter is optional and is automatically calculated as necessary.

key_modulus Property

Represents the Modulus parameter for the RSA algorithm.

Syntax

def get_key_modulus() -> bytes: ...
def set_key_modulus(value: bytes) -> None: ...

key_modulus = property(get_key_modulus, set_key_modulus)

Default Value

""

Remarks

Represents the Modulus parameter for the RSA algorithm.

keyp Property

Represents the P parameter for the RSA algorithm.

Syntax

def get_keyp() -> bytes: ...
def set_keyp(value: bytes) -> None: ...

keyp = property(get_keyp, set_keyp)

Default Value

""

Remarks

Represents the P parameter for the RSA algorithm.

key_private_key Property

This property is a PEM formatted private key.

Syntax

def get_key_private_key() -> str: ...
def set_key_private_key(value: str) -> None: ...

key_private_key = property(get_key_private_key, set_key_private_key)

Default Value

""

Remarks

This property is a PEM formatted private key. The purpose of this property is to allow easier management of the private key parameters by using only a single value.

key_public_key Property

This property is a PEM formatted public key.

Syntax

def get_key_public_key() -> str: ...
def set_key_public_key(value: str) -> None: ...

key_public_key = property(get_key_public_key, set_key_public_key)

Default Value

""

Remarks

This property is a PEM formatted public key. The purpose of this property is to allow easier management of the public key parameters by using only a single value.

keyq Property

Represents the Q parameter for the RSA algorithm.

Syntax

def get_keyq() -> bytes: ...
def set_keyq(value: bytes) -> None: ...

keyq = property(get_keyq, set_keyq)

Default Value

""

Remarks

Represents the Q parameter for the RSA algorithm.

output_file Property

The output file when encrypting or decrypting.

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 when encrypt or decrypt is called. This may be set to an absolute or relative path.

This property is only applicable to encrypt and decrypt.

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.

output_message Property

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 from the operation if output_file is not set.

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.

This property is read-only.

overwrite 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

FALSE

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_encoded Property

This is the certificate (PEM/base64 encoded).

Syntax

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

recipient_cert_encoded = property(get_recipient_cert_encoded, set_recipient_cert_encoded)

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.

recipient_cert_store Property

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

Syntax

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

recipient_cert_store = property(get_recipient_cert_store, set_recipient_cert_store)

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 are designations of 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. PKCS12 certificate store).

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() -> str: ...
def set_recipient_cert_store_password(value: str) -> None: ...

recipient_cert_store_password = property(get_recipient_cert_store_password, set_recipient_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.

recipient_cert_store_type Property

This is the type of certificate store for this certificate.

Syntax

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

recipient_cert_store_type = property(get_recipient_cert_store_type, set_recipient_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:

recipient_cert_subject Property

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

Syntax

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

recipient_cert_subject = property(get_recipient_cert_subject, set_recipient_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 displayed below.

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

recipient_key_exponent Property

Represents the Exponent parameter for the RSA algorithm.

Syntax

def get_recipient_key_exponent() -> bytes: ...
def set_recipient_key_exponent(value: bytes) -> None: ...

recipient_key_exponent = property(get_recipient_key_exponent, set_recipient_key_exponent)

Default Value

""

Remarks

Represents the Exponent parameter for the RSA algorithm.

recipient_key_modulus Property

Represents the Modulus parameter for the RSA algorithm.

Syntax

def get_recipient_key_modulus() -> bytes: ...
def set_recipient_key_modulus(value: bytes) -> None: ...

recipient_key_modulus = property(get_recipient_key_modulus, set_recipient_key_modulus)

Default Value

""

Remarks

Represents the Modulus parameter for the RSA algorithm.

recipient_key_public_key Property

This property is a PEM formatted public key.

Syntax

def get_recipient_key_public_key() -> str: ...
def set_recipient_key_public_key(value: str) -> None: ...

recipient_key_public_key = property(get_recipient_key_public_key, set_recipient_key_public_key)

Default Value

""

Remarks

This property is a PEM formatted public key. The purpose of this property is to allow easier management of the public key parameters by using only a single value.

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_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 are designations of 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. PKCS12 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 displayed below.

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

signer_key_exponent Property

Represents the Exponent parameter for the RSA algorithm.

Syntax

def get_signer_key_exponent() -> bytes: ...
def set_signer_key_exponent(value: bytes) -> None: ...

signer_key_exponent = property(get_signer_key_exponent, set_signer_key_exponent)

Default Value

""

Remarks

Represents the Exponent parameter for the RSA algorithm.

signer_key_modulus Property

Represents the Modulus parameter for the RSA algorithm.

Syntax

def get_signer_key_modulus() -> bytes: ...
def set_signer_key_modulus(value: bytes) -> None: ...

signer_key_modulus = property(get_signer_key_modulus, set_signer_key_modulus)

Default Value

""

Remarks

Represents the Modulus parameter for the RSA algorithm.

signer_key_public_key Property

This property is a PEM formatted public key.

Syntax

def get_signer_key_public_key() -> str: ...
def set_signer_key_public_key(value: str) -> None: ...

signer_key_public_key = property(get_signer_key_public_key, set_signer_key_public_key)

Default Value

""

Remarks

This property is a PEM formatted public key. The purpose of this property is to allow easier management of the public key parameters by using only a single value.

use_hex Property

Whether input or output is hex encoded.

Syntax

def get_use_hex() -> bool: ...
def set_use_hex(value: bool) -> None: ...

use_hex = property(get_use_hex, set_use_hex)

Default Value

FALSE

Remarks

This property specifies whether the encrypted data, hash_value, and hash_signature are hex encoded.

If set to True, when encrypt is called the class will perform the encryption as normal and then hex encode the output. output_message or output_file will hold hex encoded data.

If set to True, when decrypt is called the class will expect input_message or input_file to hold hex encoded data. The class will then hex decode the data and perform decryption as normal.

If set to True, when sign is called the class will compute the hash for the specified file and populate hash_value with the hex encoded hash value. It will then create the hash signature and populate hash_signature with the hex encoded hash signature value. If hash_value is specified directly it must be a hex encoded value.

If set to True, when verify_signature is called the class will compute the hash value for the specified file and populate hash_value with the hex encoded hash value. It will then hex decode hash_signature and verify the signature. hash_signature must hold a hex encoded value. If hash_value is specified directly it must be a hex encoded value.

use_oaep Property

Whether 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

Whether to use Optimal Asymmetric Encryption Padding (OAEP). By default this value is False and the class will use PKCS1.

Note: When set to True the hash_algorithm is also applicable when calling encrypt and decrypt.

use_pss Property

Whether to use RSA-PSS 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 RSA-PSS will be used when signing and verifying messages. The default value is False.

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.

create_key Method

Creates a new key.

Syntax

def create_key() -> None: ...

Remarks

This method creates a new public and private key.

When calling create_key the Key* properties are populated with a new private and public key.

RSA Keys

A RSA key is made up of a number of individual parameters.

The public key consists of the following parameters:

• key_modulus
• key_exponent

The class also includes the key_public_key property which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both sides of the encryption/signing and decryption/signature verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in key_public_key in which case the individual parameters must be sent.

The private key may be represented in one of two ways. Both are mathematically equivalent. Private key format 1:

• key_modulus
• keyp
• keyq
• key_dp
• key_dq

Private key format 2 is simpler but has decreased performance when decrypting and signing. This format is:

• key_modulus
• keyd

The class also include the key_private_key property which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

decrypt Method

Decrypts the input data using the specified private key.

Syntax

def decrypt() -> None: ...

Remarks

This method decrypts the input data using the private key specified in the Key* properties. Alternatively, a certificate may be specified by setting 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.

Key Size and the Maximum Length of Data

RSA has an upper limit to the amount of data that can be encrypted or decrypted, also known as message length. This can typically be calculated as the size of the key minus the size of the RSA header and padding.

When not using OAEP, the following formula and table can be referenced. (RSA Key Bytes) - (Header Bytes) = Length of data, where Header Bytes is always 11.

When using OAEP, the following formula and table can be referenced. (RSA Key Bytes) - (2 * Hash Length Bytes) - 2 = Length of data. The table below assumes SHA-256 for the hash, so Hash Length Bytes is 32.

encrypt Method

Encrypts the input data using the recipient's public key.

Syntax

def encrypt() -> None: ...

Remarks

This method encrypts the input data using the public key specified in the RecipientKey* properties. Alternatively, a certificate may be specified by setting recipient_cert

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.

Key Size and the Maximum Length of Data

RSA has an upper limit to the amount of data that can be encrypted or decrypted, also known as message length. This can typically be calculated as the size of the key minus the size of the RSA header and padding.

When not using OAEP, the following formula and table can be referenced. (RSA Key Bytes) - (Header Bytes) = Length of data, where Header Bytes is always 11.

When using OAEP, the following formula and table can be referenced. (RSA Key Bytes) - (2 * Hash Length Bytes) - 2 = Length of data. The table below assumes SHA-256 for the hash, so Hash Length Bytes is 32.

reset Method

Resets the class.

Syntax

def reset() -> None: ...

Remarks

When called, the class will reset all of its properties to their default values.

sign Method

Creates a hash signature.

Syntax

def sign() -> None: ...

Remarks

This method will create a hash signature.

Before calling this method specify the input file by setting input_file or input_message.

A key is required to create the hash signature. You may create a new key by calling create_key, or specify an existing key pair in key. Alternatively, a certificate may be specified by setting certificate. When this method is called the class will compute the hash for the specified file and populate hash_value. It will then create the hash signature using the specified key and populate hash_signature.

To create the hash signature without first computing the hash simply specify hash_value before calling this method.

The on_progress event will fire with updates for the hash computation progress only. The hash signature creation process is quick and does not require progress updates.

verify_signature Method

Verifies the signature for the specified data.

Syntax

def verify_signature() -> bool: ...

Remarks

This method will verify a hash signature.

Before calling this method specify the input file by setting input_file or input_message.

A public key and the hash signature are required to perform the signature verification. Specify the public key in signer_key. Alternatively, a certificate may be specified by setting signer_cert. Specify the hash signature in hash_signature.

When this method is called the class will compute the hash for the specified file and populate hash_value. It will verify the signature using the specified signer_key and hash_signature.

To verify the hash signature without first computing the hash simply specify hash_value before calling this method.

The on_progress event will fire with updates for the hash computation progress only. The hash signature verification process is quick and does not require progress updates.

on_error Event

Information about errors during data delivery.

Syntax

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

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

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

Remarks

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

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 Error Codes section.

on_progress Event

Fired as progress is made.

Syntax

class RSAProgressEventParams(object):
  @property
  def bytes_processed() -> int: ...

  @property
  def percent_processed() -> int: ...

# In class RSA:
@property
def on_progress() -> Callable[[RSAProgressEventParams], None]: ...
@on_progress.setter
def on_progress(event_hook: Callable[[RSAProgressEventParams], None]) -> None: ...

Remarks

This event is fired automatically as data is processed by the class.

The PercentProcessed parameter indicates the current status of the operation.

The BytesProcessed parameter holds the total number of bytes processed so far.

RSA 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.

RSA Config Settings

Base Config Settings

RSA Errors

RSA Errors

	102   No Key specified.
	104   Cannot read or write file.
	105   key parameters incorrect.
	106   Cannot create hash.
	111   OutputFile already exists and Overwrite is False.
	113   Input data or HashValue must be specified.
	121   Invalid certificate.
	124   HashSignature must be specified.
	304   Cannot write file.
	305   Cannot read file.
	306   Cannot create file.
	1101   Missing RSA parameter: Modulus
	1102   Invalid RSA parameter: Modulus cannot be zero.
	1103   Missing RSA parameters: Public or Private exponent must be present.
	1104   Invalid RSA parameter: Exponent cannot be zero.
	1105   Invalid RSA parameter: D cannot be zero.
	1106   Invalid hash algorithm.
	1107   Missing hash value.
	1108   HashSignature must be specified.
	1109   Invalid hash size.
	1110   Public key must be specified.
	1111   Key must be specified.
	1112   RSA key too short to sign message.
	1113   Missing the data to encrypt/decrypt.
	1114   Invalid cipher length. The data may not have been encrypted with the public key corresponding to the specified private key data.
	1115   Invalid cipher text. The data may not have been encrypted with the public key corresponding to the specified private key data.
	1116   Inadequate padding. The data may not have been encrypted with the public key corresponding to the specified private key data.
	1117   Missing delimiter. The data may not have been encrypted with the public key corresponding to the specified private key data.
	1118   Message too long.