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- #
- # 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,
- # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- # POSSIBILITY OF SUCH DAMAGE.
- # ===================================================================
- from Crypto.Util.py3compat import *
- from Crypto.Util.asn1 import (
- DerNull,
- DerSequence,
- DerObjectId,
- DerOctetString,
- )
- from Crypto.IO._PBES import PBES1, PBES2, PbesError
- __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):
- """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).
- 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:
- passphrase = tobytes(passphrase)
- found = False
- try:
- p8_private_key = PBES1.decrypt(p8_private_key, passphrase)
- 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)
- 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)
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