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# Lead Maintainer: Virgil Security Inc. <support@virgilsecurity.com>


from ctypes import *
from ._c_bridge import VscfKdf2
from ._c_bridge import VscfImplTag
from ._c_bridge import VscfStatus
from virgil_crypto_lib.common._c_bridge import Data
from virgil_crypto_lib.common._c_bridge import Buffer
from .alg import Alg
from .kdf import Kdf


class Kdf2(Alg, Kdf):
    """Virgil Security implementation of the KDF2 (ISO-18033-2) algorithm."""

    def __init__(self):
        """Create underlying C context."""
        self._lib_vscf_kdf2 = VscfKdf2()
        self._c_impl = None
        self._ctx = None
        self.ctx = self._lib_vscf_kdf2.vscf_kdf2_new()

    def __delete__(self, instance):
        """Destroy underlying C context."""
        self._lib_vscf_kdf2.vscf_kdf2_delete(self.ctx)

    def set_hash(self, hash):
        self._lib_vscf_kdf2.vscf_kdf2_use_hash(self.ctx, hash.c_impl)

    def alg_id(self):
        """Provide algorithm identificator."""
        result = self._lib_vscf_kdf2.vscf_kdf2_alg_id(self.ctx)
        return result

    def produce_alg_info(self):
        """Produce object with algorithm information and configuration parameters."""
        result = self._lib_vscf_kdf2.vscf_kdf2_produce_alg_info(self.ctx)
        instance = VscfImplTag.get_type(result)[0].take_c_ctx(cast(result, POINTER(VscfImplTag.get_type(result)[1])))
        return instance

    def restore_alg_info(self, alg_info):
        """Restore algorithm configuration from the given object."""
        status = self._lib_vscf_kdf2.vscf_kdf2_restore_alg_info(self.ctx, alg_info.c_impl)
        VscfStatus.handle_status(status)

    def derive(self, data, key_len):
        """Derive key of the requested length from the given data."""
        d_data = Data(data)
        key = Buffer(key_len)
        self._lib_vscf_kdf2.vscf_kdf2_derive(self.ctx, d_data.data, key_len, key.c_buffer)
        return key.get_bytes()

    @classmethod
    def take_c_ctx(cls, c_ctx):
        inst = cls.__new__(cls)
        inst._lib_vscf_kdf2 = VscfKdf2()
        inst.ctx = c_ctx
        return inst

    @classmethod
    def use_c_ctx(cls, c_ctx):
        inst = cls.__new__(cls)
        inst._lib_vscf_kdf2 = VscfKdf2()
        inst.ctx = inst._lib_vscf_kdf2.vscf_kdf2_shallow_copy(c_ctx)
        return inst

    @property
    def c_impl(self):
        return self._c_impl

    @property
    def ctx(self):
        return self._ctx

    @ctx.setter
    def ctx(self, value):
        self._ctx = self._lib_vscf_kdf2.vscf_kdf2_shallow_copy(value)
        self._c_impl = self._lib_vscf_kdf2.vscf_kdf2_impl(self.ctx)
