Edit File: 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, # 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 (byte string): 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). passphrase (bytes string 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. The default value is ``PBKDF2WithHMAC-SHA1AndDES-EDE3-CBC``. prot_params (dictionary): Parameters for the protection algorithm. +------------------+-----------------------------------------------+ | Key | Description | +==================+===============================================+ | iteration_count | The KDF algorithm is repeated several times to| | | slow down brute force attacks on passwords | | | (called *N* or CPU/memory cost in scrypt). | | | The default value for PBKDF2 is 1000. | | | The default value for scrypt is 16384. | +------------------+-----------------------------------------------+ | salt_size | Salt is used to thwart dictionary and rainbow | | | attacks on passwords. The default value is 8 | | | bytes. | +------------------+-----------------------------------------------+ | block_size | *(scrypt only)* Memory-cost (r). The default | | | value is 8. | +------------------+-----------------------------------------------+ | parallelization | *(scrypt only)* CPU-cost (p). The default | | | value is 1. | +------------------+-----------------------------------------------+ 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`. Return: The PKCS#8-wrapped private key (possibly encrypted), as a byte string. """ # # 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 (byte string): The private key wrapped into a PKCS#8 blob, DER encoded. 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 (byte string, DER encoded) #. the associated parameters (byte string, 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)