spresso.utils package

Submodules

spresso.utils.base module

create_nonce(length)

Generates random bytes of specified length. UNIX-like system will query /dev/urandom, Windows will use CryptGenRandom()

Parameters:length (int) – The length of the random sequence. Returns:The random sequence. Return type:bytes

create_random_characters(length, chars='ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789')

Generates a random string of a specified length. Per default the charset consists of uppercase ASCII letters and digits.

Parameters:

• length (int) – The length of the random string sequence.
• chars (str) – The charset from which to choose.

Returns:

The random string sequence.

Return type:

str

from_b64(data_b64, return_bytes=False)

Wrapper around base64.b64decode() to decode data using Base64.

Parameters:

• data_b64 (str, bytes) – The Base64-encoded data.
• return_bytes (bool) – Flag to indicate if bytes or string should be returned.

Returns:

The decoded data.

Return type:

str, bytes

get_file_content(path, mode)

Wrapper around open().

Parameters:

• path (str) – The path to the file.
• mode (str) – The mode in which the file should be opened.

Raises:

• ValueError – The path or mode is invalid.
• FileNotFoundError – The file could not found at the given path.

Returns:

The file contents.

Return type:

str

get_resource(resource_path, path)

Method to retrieve resource files from the package installation directory.

Parameters:

• resource_path (str) – The path where resources are stored.
• path (str) – The relative path to the resource.

Returns:

The file content of the resource.

Return type:

str

get_url(scheme, netloc, path='', params='', query='', fragment='')

Wrapper around urllib.parse.ParseResult and urllib.parse.urlunparse() to retrieve an URL.

Parameters:

• scheme (str) – The URL scheme.
• netloc (str) – The URL domain.
• path (str) – The URL path.
• params (str) – The URL parameters.
• query (str) – The URL query arguments.
• fragment (str) – The URL fragment.

Returns:

The URL.

Return type:

str

to_b64(data)

Wrapper around base64.b64encode() to encode data using Base64.

Parameters:data (str, bytes) – The data. Returns:The Base64-encoded data. Return type:str

update_existing_keys(source, target)

Wrapper around dict.update(). This function only updates the existing keys in the dictionary.

Parameters:

• source (dict) – The source dictionary.
• target (dict) – The target dictionary.

spresso.utils.crypto module

This module provides the necessary cryptographic primitives for the system. It is based on the cryptography package.

create_signature(private_key, data)

Method to create a PKCS#1 signature using SHA256.

Load a RSA private key in PEM format using load_pem_private_key. Then configure a signer object and sign the passed in data.

Parameters:

• private_key (bytes) – The RSA private key used during signature creation.
• data (bytes) – The data to be signed.

Returns:

The signature.

Return type:

bytes

decrypt_aes_gcm(key, iv, auth_tag, cipher_text, associated_data=b'')

Method to decrypt AES in GCM mode.

Constructs a Cipher object from key, iv and authentication tag. The associated data is passed in during decryption.

Parameters:

• key (bytes) – The symmetric key used during decryption.
• iv (bytes) – The initialisation vector used during decryption.
• auth_tag (bytes) – The authentication tag used during decryption.
• cipher_text (bytes) – Cipher text to decrypt.
• associated_data (bytes) – Additional authentication data that was passed in during encryption.

Returns:

The decrypted cipher text.

Return type:

bytes

Raises:

InvalidTag – The authentication tag in combination with the given parameters is invalid.

encrypt_aes_gcm(key, iv, plaintext, associated_data=b'')

Method to encrypt AES in GCM mode.

Constructs a Cipher object from key, iv. The plain text is passed in during encryption.

Parameters:

• key (bytes) – The symmetric key used during encryption.
• iv (bytes) – The initialisation vector used during encryption.
• plaintext (bytes) – Plain text to encrypt.
• associated_data (bytes) – Additional data to authenticate.

Returns:

The encrypted plain text as bytes and the authentication tag

as bytes.

Return type:

tuple

Raises:

InvalidTag – The authentication tag in combination with the given parameters is invalid.

verify_signature(public_key, signature, data)

Method to verify a PKCS#1 signature using SHA256.

Load a RSA public key in PEM format using load_pem_public_key. Then configure a verifier object and verify the passed in data.

Parameters:

• public_key (bytes) – The RSA public key used in verification.
• signature (bytes) – The signature to verify.
• data (bytes) – The expected signed data, which should be verified.

Raises:

InvalidSignature – The expected data was invalid in respect to the signature.

spresso.utils.error module

exception InvalidSettings

Bases: Exception

Raised by spresso.grant.base.SettingsMixin in case an invalid settings class was passed to the instance.

exception InvalidSiteAdapter

Bases: Exception

Raised by spresso.grant.base.SiteAdapterMixin in case an invalid site adapter was passed to the instance.

exception SpressoBaseError(error, uri=None, message=None)

Bases: Exception

Base class used by SPRESSO specific errors.

Parameters:

• error (str) – Identifier of the error.
• uri (str) – URL at which the error occurred.
• message (str) – Short message that describes the error.

exception SpressoInvalidError(error, uri=None, message=None)

Bases: spresso.utils.error.SpressoBaseError

Indicates an error during validation of a request.

exception UnsupportedAdditionalData

Bases: Exception

Indicates incorrectly formatted additional data.

exception UnsupportedGrantError

Bases: Exception

Indicates that a requested grant is not supported by the server.

exception UserNotAuthenticated

Bases: Exception

Raised by spresso.grant.authentication.site_adapter. identity_provider.SignatureSiteAdapter to indicate an unauthenticated user.

spresso.utils.log module

There is one logger available to log uncaught exceptions in <spresso.controller.application>. If logging has not been configured, you will likely see this error:

Make sure that logging is configured to avoid this:

Module contents