# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import absolute_import, division, print_function

import abc

import six


@six.add_metaclass(abc.ABCMeta)
class CipherAlgorithm(object):
    @abc.abstractproperty
    def name(self):
        """
        A string naming this mode (e.g. "AES", "Camellia").
        """

    @abc.abstractproperty
    def key_size(self):
        """
        The size of the key being used as an integer in bits (e.g. 128, 256).
        """


@six.add_metaclass(abc.ABCMeta)
class BlockCipherAlgorithm(object):
    @abc.abstractproperty
    def block_size(self):
        """
        The size of a block as an integer in bits (e.g. 64, 128).
        """


@six.add_metaclass(abc.ABCMeta)
class Mode(object):
    @abc.abstractproperty
    def name(self):
        """
        A string naming this mode (e.g. "ECB", "CBC").
        """

    @abc.abstractmethod
    def validate_for_algorithm(self, algorithm):
        """
        Checks that all the necessary invariants of this (mode, algorithm)
        combination are met.
        """


@six.add_metaclass(abc.ABCMeta)
class ModeWithInitializationVector(object):
    @abc.abstractproperty
    def initialization_vector(self):
        """
        The value of the initialization vector for this mode as bytes.
        """


@six.add_metaclass(abc.ABCMeta)
class ModeWithNonce(object):
    @abc.abstractproperty
    def nonce(self):
        """
        The value of the nonce for this mode as bytes.
        """


@six.add_metaclass(abc.ABCMeta)
class ModeWithAuthenticationTag(object):
    @abc.abstractproperty
    def tag(self):
        """
        The value of the tag supplied to the constructor of this mode.
        """


@six.add_metaclass(abc.ABCMeta)
class CipherContext(object):
    @abc.abstractmethod
    def update(self, data):
        """
        Processes the provided bytes through the cipher and returns the results
        as bytes.
        """

    @abc.abstractmethod
    def finalize(self):
        """
        Returns the results of processing the final block as bytes.
        """


@six.add_metaclass(abc.ABCMeta)
class AEADCipherContext(object):
    @abc.abstractmethod
    def authenticate_additional_data(self, data):
        """
        Authenticates the provided bytes.
        """


@six.add_metaclass(abc.ABCMeta)
class AEADEncryptionContext(object):
    @abc.abstractproperty
    def tag(self):
        """
        Returns tag bytes. This is only available after encryption is
        finalized.
        """


@six.add_metaclass(abc.ABCMeta)
class PaddingContext(object):
    @abc.abstractmethod
    def update(self, data):
        """
        Pads the provided bytes and returns any available data as bytes.
        """

    @abc.abstractmethod
    def finalize(self):
        """
        Finalize the padding, returns bytes.
        """


@six.add_metaclass(abc.ABCMeta)
class HashAlgorithm(object):
    @abc.abstractproperty
    def name(self):
        """
        A string naming this algorithm (e.g. "sha256", "md5").
        """

    @abc.abstractproperty
    def digest_size(self):
        """
        The size of the resulting digest in bytes.
        """

    @abc.abstractproperty
    def block_size(self):
        """
        The internal block size of the hash algorithm in bytes.
        """


@six.add_metaclass(abc.ABCMeta)
class HashContext(object):
    @abc.abstractproperty
    def algorithm(self):
        """
        A HashAlgorithm that will be used by this context.
        """

    @abc.abstractmethod
    def update(self, data):
        """
        Processes the provided bytes through the hash.
        """

    @abc.abstractmethod
    def finalize(self):
        """
        Finalizes the hash context and returns the hash digest as bytes.
        """

    @abc.abstractmethod
    def copy(self):
        """
        Return a HashContext that is a copy of the current context.
        """


@six.add_metaclass(abc.ABCMeta)
class RSAPrivateKey(object):
    @abc.abstractmethod
    def signer(self, padding, algorithm):
        """
        Returns an AsymmetricSignatureContext used for signing data.
        """

    @abc.abstractmethod
    def decrypt(self, ciphertext, padding):
        """
        Decrypts the provided ciphertext.
        """

    @abc.abstractproperty
    def key_size(self):
        """
        The bit length of the public modulus.
        """

    @abc.abstractmethod
    def public_key(self):
        """
        The RSAPublicKey associated with this private key.
        """


@six.add_metaclass(abc.ABCMeta)
class RSAPrivateKeyWithNumbers(RSAPrivateKey):
    @abc.abstractmethod
    def private_numbers(self):
        """
        Returns an RSAPrivateNumbers.
        """


@six.add_metaclass(abc.ABCMeta)
class RSAPublicKey(object):
    @abc.abstractmethod
    def verifier(self, signature, padding, algorithm):
        """
        Returns an AsymmetricVerificationContext used for verifying signatures.
        """

    @abc.abstractmethod
    def encrypt(self, plaintext, padding):
        """
        Encrypts the given plaintext.
        """

    @abc.abstractproperty
    def key_size(self):
        """
        The bit length of the public modulus.
        """


@six.add_metaclass(abc.ABCMeta)
class RSAPublicKeyWithNumbers(RSAPublicKey):
    @abc.abstractmethod
    def public_numbers(self):
        """
        Returns an RSAPublicNumbers
        """


@six.add_metaclass(abc.ABCMeta)
class DSAParameters(object):
    @abc.abstractmethod
    def generate_private_key(self):
        """
        Generates and returns a DSAPrivateKey.
        """


@six.add_metaclass(abc.ABCMeta)
class DSAParametersWithNumbers(DSAParameters):
    @abc.abstractmethod
    def parameter_numbers(self):
        """
        Returns a DSAParameterNumbers.
        """


@six.add_metaclass(abc.ABCMeta)
class DSAPrivateKey(object):
    @abc.abstractproperty
    def key_size(self):
        """
        The bit length of the prime modulus.
        """

    @abc.abstractmethod
    def public_key(self):
        """
        The DSAPublicKey associated with this private key.
        """

    @abc.abstractmethod
    def parameters(self):
        """
        The DSAParameters object associated with this private key.
        """


@six.add_metaclass(abc.ABCMeta)
class DSAPrivateKeyWithNumbers(DSAPrivateKey):
    @abc.abstractmethod
    def private_numbers(self):
        """
        Returns a DSAPrivateNumbers.
        """


@six.add_metaclass(abc.ABCMeta)
class DSAPublicKey(object):
    @abc.abstractproperty
    def key_size(self):
        """
        The bit length of the prime modulus.
        """

    @abc.abstractmethod
    def parameters(self):
        """
        The DSAParameters object associated with this public key.
        """


@six.add_metaclass(abc.ABCMeta)
class DSAPublicKeyWithNumbers(DSAPublicKey):
    @abc.abstractmethod
    def public_numbers(self):
        """
        Returns a DSAPublicNumbers.
        """


@six.add_metaclass(abc.ABCMeta)
class AsymmetricSignatureContext(object):
    @abc.abstractmethod
    def update(self, data):
        """
        Processes the provided bytes and returns nothing.
        """

    @abc.abstractmethod
    def finalize(self):
        """
        Returns the signature as bytes.
        """


@six.add_metaclass(abc.ABCMeta)
class AsymmetricVerificationContext(object):
    @abc.abstractmethod
    def update(self, data):
        """
        Processes the provided bytes and returns nothing.
        """

    @abc.abstractmethod
    def verify(self):
        """
        Raises an exception if the bytes provided to update do not match the
        signature or the signature does not match the public key.
        """


@six.add_metaclass(abc.ABCMeta)
class AsymmetricPadding(object):
    @abc.abstractproperty
    def name(self):
        """
        A string naming this padding (e.g. "PSS", "PKCS1").
        """


@six.add_metaclass(abc.ABCMeta)
class KeyDerivationFunction(object):
    @abc.abstractmethod
    def derive(self, key_material):
        """
        Deterministically generates and returns a new key based on the existing
        key material.
        """

    @abc.abstractmethod
    def verify(self, key_material, expected_key):
        """
        Checks whether the key generated by the key material matches the
        expected derived key. Raises an exception if they do not match.
        """


@six.add_metaclass(abc.ABCMeta)
class CMACContext(object):
    @abc.abstractmethod
    def update(self, data):
        """
        Processes the provided bytes.
        """

    def finalize(self):
        """
        Returns the message authentication code as bytes.
        """

    @abc.abstractmethod
    def copy(self):
        """
        Return a CMACContext that is a copy of the current context.
        """


@six.add_metaclass(abc.ABCMeta)
class EllipticCurve(object):
    @abc.abstractproperty
    def name(self):
        """
        The name of the curve. e.g. secp256r1.
        """

    @abc.abstractproperty
    def key_size(self):
        """
        The bit length of the base point of the curve.
        """


@six.add_metaclass(abc.ABCMeta)
class EllipticCurveSignatureAlgorithm(object):
    @abc.abstractproperty
    def algorithm(self):
        """
        The digest algorithm used with this signature.
        """


@six.add_metaclass(abc.ABCMeta)
class EllipticCurvePrivateKey(object):
    @abc.abstractmethod
    def signer(self, signature_algorithm):
        """
        Returns an AsymmetricSignatureContext used for signing data.
        """

    @abc.abstractmethod
    def public_key(self):
        """
        The EllipticCurvePublicKey for this private key.
        """

    @abc.abstractproperty
    def curve(self):
        """
        The EllipticCurve that this key is on.
        """


@six.add_metaclass(abc.ABCMeta)
class EllipticCurvePublicKey(object):
    @abc.abstractmethod
    def verifier(self, signature, signature_algorithm):
        """
        Returns an AsymmetricVerificationContext used for signing data.
        """

    @abc.abstractproperty
    def curve(self):
        """
        The EllipticCurve that this key is on.
        """
