shanxia2.0/backend/venv/lib/python3.9/site-packages/Crypto/IO/PKCS8.py

#
#  PublicKey/PKCS8.py : PKCS#8 functions
#
# ===================================================================
#
# Copyright (c) 2014, Legrandin <helderijs@gmail.com>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in
#    the documentation and/or other materials provided with the
#    distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# ===================================================================


from Crypto.Util.py3compat import *

from Crypto.Util.asn1 import (
            DerNull,
            DerSequence,
            DerObjectId,
            DerOctetString,
            )

from Crypto.IO._PBES import PBES1, PBES2, PbesError, _DEFAULT_MAX_ITERATION_COUNT


__all__ = ['wrap', 'unwrap']


def wrap(private_key, key_oid, passphrase=None, protection=None,
         prot_params=None, key_params=DerNull(), randfunc=None):
    """Wrap a private key into a PKCS#8 blob (clear or encrypted).

    Args:

      private_key (bytes):
        The private key encoded in binary form. The actual encoding is
        algorithm specific. In most cases, it is DER.

      key_oid (string):
        The object identifier (OID) of the private key to wrap.
        It is a dotted string, like ``'1.2.840.113549.1.1.1'`` (for RSA keys)
        or ``'1.2.840.10045.2.1'`` (for ECC keys).

    Keyword Args:

      passphrase (bytes or string):
        The secret passphrase from which the wrapping key is derived.
        Set it only if encryption is required.

      protection (string):
        The identifier of the algorithm to use for securely wrapping the key.
        Refer to :ref:`the encryption parameters<enc_params>` .
        The default value is ``'PBKDF2WithHMAC-SHA1AndDES-EDE3-CBC'``.

      prot_params (dictionary):
        Parameters for the key derivation function (KDF).
        Refer to :ref:`the encryption parameters<enc_params>` .

      key_params (DER object or None):
        The ``parameters`` field to use in the ``AlgorithmIdentifier``
        SEQUENCE. If ``None``, no ``parameters`` field will be added.
        By default, the ASN.1 type ``NULL`` is used.

      randfunc (callable):
        Random number generation function; it should accept a single integer
        N and return a string of random data, N bytes long.
        If not specified, a new RNG will be instantiated
        from :mod:`Crypto.Random`.

    Returns:
      bytes: The PKCS#8-wrapped private key (possibly encrypted).
    """

    #
    #   PrivateKeyInfo ::= SEQUENCE {
    #       version                 Version,
    #       privateKeyAlgorithm     PrivateKeyAlgorithmIdentifier,
    #       privateKey              PrivateKey,
    #       attributes              [0]  IMPLICIT Attributes OPTIONAL
    #   }
    #
    if key_params is None:
        algorithm = DerSequence([DerObjectId(key_oid)])
    else:
        algorithm = DerSequence([DerObjectId(key_oid), key_params])

    pk_info = DerSequence([
                0,
                algorithm,
                DerOctetString(private_key)
            ])
    pk_info_der = pk_info.encode()

    if passphrase is None:
        return pk_info_der

    if not passphrase:
        raise ValueError("Empty passphrase")

    # Encryption with PBES2
    passphrase = tobytes(passphrase)
    if protection is None:
        protection = 'PBKDF2WithHMAC-SHA1AndDES-EDE3-CBC'
    return PBES2.encrypt(pk_info_der, passphrase,
                         protection, prot_params, randfunc)


def unwrap(p8_private_key, passphrase=None, max_iteration_count=None):
    """Unwrap a private key from a PKCS#8 blob (clear or encrypted).

    Args:
      p8_private_key (bytes):
        The private key wrapped into a PKCS#8 container, DER encoded.

    Keyword Args:
      passphrase (byte string or string):
        The passphrase to use to decrypt the blob (if it is encrypted).
      max_iteration_count (integer):
        The maximum value allowed for the PBKDF2/scrypt iteration count.
        An attacker could craft a malicious key blob that requires an
        extremely high number of iterations, tying up the CPU for hours.
        The default value is None (enforcing the default limit of 50,000,000).
        Set it to ``0`` to disable the check.

    Return:
      A tuple containing

       #. the algorithm identifier of the wrapped key (OID, dotted string)
       #. the private key (bytes, DER encoded)
       #. the associated parameters (bytes, DER encoded) or ``None``

    Raises:
      ValueError : if decoding fails
    """

    if passphrase is not None:
        passphrase = tobytes(passphrase)

        found = False
        try:
            p8_private_key = PBES1.decrypt(p8_private_key, passphrase,
                                           max_iteration_count=max_iteration_count)
            found = True
        except PbesError as e:
            error_str = "PBES1[%s]" % str(e)
        except ValueError:
            error_str = "PBES1[Invalid]"

        if not found:
            try:
                p8_private_key = PBES2.decrypt(p8_private_key, passphrase,
                                               max_iteration_count=max_iteration_count)
                found = True
            except PbesError as e:
                error_str += ",PBES2[%s]" % str(e)
            except ValueError:
                error_str += ",PBES2[Invalid]"

        if not found:
            raise ValueError("Error decoding PKCS#8 (%s)" % error_str)

    pk_info = DerSequence().decode(p8_private_key, nr_elements=(2, 3, 4, 5))
    if len(pk_info) == 2 and not passphrase:
        raise ValueError("Not a valid clear PKCS#8 structure "
                         "(maybe it is encrypted?)")

    # RFC5208, PKCS#8, version is v1(0)
    #
    #   PrivateKeyInfo ::= SEQUENCE {
    #       version                 Version,
    #       privateKeyAlgorithm     PrivateKeyAlgorithmIdentifier,
    #       privateKey              PrivateKey,
    #       attributes              [0]  IMPLICIT Attributes OPTIONAL
    #   }
    #
    # RFC5915, Asymmetric Key Package, version is v2(1)
    #
    #   OneAsymmetricKey ::= SEQUENCE {
    #       version                   Version,
    #       privateKeyAlgorithm       PrivateKeyAlgorithmIdentifier,
    #       privateKey                PrivateKey,
    #       attributes            [0] Attributes OPTIONAL,
    #       ...,
    #       [[2: publicKey        [1] PublicKey OPTIONAL ]],
    #       ...
    #   }

    if pk_info[0] == 0:
        if len(pk_info) not in (3, 4):
            raise ValueError("Not a valid PrivateKeyInfo SEQUENCE")
    elif pk_info[0] == 1:
        if len(pk_info) not in (3, 4, 5):
            raise ValueError("Not a valid PrivateKeyInfo SEQUENCE")
    else:
        raise ValueError("Not a valid PrivateKeyInfo SEQUENCE")

    algo = DerSequence().decode(pk_info[1], nr_elements=(1, 2))
    algo_oid = DerObjectId().decode(algo[0]).value
    if len(algo) == 1:
        algo_params = None
    else:
        try:
            DerNull().decode(algo[1])
            algo_params = None
        except:
            algo_params = algo[1]

    # PrivateKey ::= OCTET STRING
    private_key = DerOctetString().decode(pk_info[2]).payload

    # We ignore attributes and (for v2 only) publickey

    return (algo_oid, private_key, algo_params)