def _import_pkcs8(encoded, passphrase): from crypto.IO import PKCS8 # From RFC5915, Section 1: # # Distributing an EC private key with PKCS#8 [RFC5208] involves including: # a) id-ecPublicKey, id-ecDH, or id-ecMQV (from [RFC5480]) with the # namedCurve as the parameters in the privateKeyAlgorithm field; and # b) ECPrivateKey in the PrivateKey field, which is an OCTET STRING. algo_oid, private_key, params = PKCS8.unwrap(encoded, passphrase) # We accept id-ecPublicKey, id-ecDH, id-ecMQV without making any # distiction for now. unrestricted_oid = "1.2.840.10045.2.1" ecdh_oid = "1.3.132.1.12" ecmqv_oid = "1.3.132.1.13" if algo_oid not in (unrestricted_oid, ecdh_oid, ecmqv_oid): raise UnsupportedEccFeature("Unsupported ECC purpose (OID: %s)" % algo_oid) curve_oid = DerObjectId().decode(params).value return _import_private_der(private_key, passphrase, curve_oid)
def _export_private_der(self, include_ec_params=True): assert self.has_private() # ECPrivateKey ::= SEQUENCE { # version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), # privateKey OCTET STRING, # parameters [0] ECParameters {{ NamedCurve }} OPTIONAL, # publicKey [1] BIT STRING OPTIONAL # } # Public key - uncompressed form order_bytes = _curve.order.size_in_bytes() public_key = (bchr(4) + self.pointQ.x.to_bytes(order_bytes) + self.pointQ.y.to_bytes(order_bytes)) seq = [1, DerOctetString(self.d.to_bytes(order_bytes)), DerObjectId(_curve.oid, explicit=0), DerBitString(public_key, explicit=1)] if not include_ec_params: del seq[2] return DerSequence(seq).encode()
def _export_subjectPublicKeyInfo(self, compress): # See 2.2 in RFC5480 and 2.3.3 in SEC1 # The first byte is: # - 0x02: compressed, only X-coordinate, Y-coordinate is even # - 0x03: compressed, only X-coordinate, Y-coordinate is odd # - 0x04: uncompressed, X-coordinate is followed by Y-coordinate # # PAI is in theory encoded as 0x00. order_bytes = _curve.order.size_in_bytes() if compress: first_byte = 2 + self.pointQ.y.is_odd() public_key = (bchr(first_byte) + self.pointQ.x.to_bytes(order_bytes)) else: public_key = (bchr(4) + self.pointQ.x.to_bytes(order_bytes) + self.pointQ.y.to_bytes(order_bytes)) unrestricted_oid = "1.2.840.10045.2.1" return _create_subject_public_key_info(unrestricted_oid, public_key, DerObjectId(_curve.oid))
def _create_subject_public_key_info(algo_oid, secret_key, params=None): if params is None: params = DerNull() spki = DerSequence([ DerSequence([DerObjectId(algo_oid), params]), DerBitString(secret_key) ]) return spki.encode()
def _export_pkcs8(self, **kwargs): if kwargs.get('passphrase', None) is not None and 'protection' not in kwargs: raise ValueError("At least the 'protection' parameter should be present") unrestricted_oid = "1.2.840.10045.2.1" private_key = self._export_private_der(include_ec_params=False) result = PKCS8.wrap(private_key, unrestricted_oid, key_params=DerObjectId(_curve.oid), **kwargs) return result
def testEncode1(self): der = DerObjectId('1.2.840.113549.1.1.1') self.assertEqual(der.encode(), b('\x06\x09\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01')) # der = DerObjectId() der.value = '1.2.840.113549.1.1.1' self.assertEqual(der.encode(), b('\x06\x09\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01'))
def decrypt(data, passphrase): """Decrypt a piece of data using a passphrase and *PBES1*. The algorithm to use is automatically detected. :Parameters: data : byte string The piece of data to decrypt. passphrase : byte string The passphrase to use for decrypting the data. :Returns: The decrypted data, as a binary string. """ enc_private_key_info = DerSequence().decode(data) encrypted_algorithm = DerSequence().decode(enc_private_key_info[0]) encrypted_data = DerOctetString().decode( enc_private_key_info[1]).payload pbe_oid = DerObjectId().decode(encrypted_algorithm[0]).value cipher_params = {} if pbe_oid == "1.2.840.113549.1.5.3": # PBE_MD5_DES_CBC hashmod = MD5 ciphermod = DES elif pbe_oid == "1.2.840.113549.1.5.6": # PBE_MD5_RC2_CBC hashmod = MD5 ciphermod = ARC2 cipher_params['effective_keylen'] = 64 elif pbe_oid == "1.2.840.113549.1.5.10": # PBE_SHA1_DES_CBC hashmod = SHA1 ciphermod = DES elif pbe_oid == "1.2.840.113549.1.5.11": # PBE_SHA1_RC2_CBC hashmod = SHA1 ciphermod = ARC2 cipher_params['effective_keylen'] = 64 else: raise PbesError("Unknown OID for PBES1") pbe_params = DerSequence().decode(encrypted_algorithm[1], nr_elements=2) salt = DerOctetString().decode(pbe_params[0]).payload iterations = pbe_params[1] key_iv = PBKDF1(passphrase, salt, 16, iterations, hashmod) key, iv = key_iv[:8], key_iv[8:] cipher = ciphermod.new(key, ciphermod.MODE_CBC, iv, **cipher_params) pt = cipher.decrypt(encrypted_data) return unpad(pt, cipher.block_size)
def _import_private_der(encoded, passphrase, curve_oid=None): # See RFC5915 https://tools.ietf.org/html/rfc5915 # # ECPrivateKey ::= SEQUENCE { # version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), # privateKey OCTET STRING, # parameters [0] ECParameters {{ NamedCurve }} OPTIONAL, # publicKey [1] BIT STRING OPTIONAL # } private_key = DerSequence().decode(encoded, nr_elements=(3, 4)) if private_key[0] != 1: raise ValueError("Incorrect ECC private key version") try: parameters = DerObjectId(explicit=0).decode(private_key[2]).value if curve_oid is not None and parameters != curve_oid: raise ValueError("Curve mismatch") curve_oid = parameters except ValueError: pass if curve_oid is None: raise ValueError("No curve found") for curve_name, curve in _curves.items(): if curve.oid == curve_oid: break else: raise UnsupportedEccFeature("Unsupported ECC curve (OID: %s)" % curve_oid) scalar_bytes = DerOctetString().decode(private_key[1]).payload modulus_bytes = curve.p.size_in_bytes() if len(scalar_bytes) != modulus_bytes: raise ValueError("Private key is too small") d = Integer.from_bytes(scalar_bytes) # Decode public key (if any) if len(private_key) == 4: public_key_enc = DerBitString(explicit=1).decode(private_key[3]).value public_key = _import_public_der(curve_oid, public_key_enc) point_x = public_key.pointQ.x point_y = public_key.pointQ.y else: point_x = point_y = None return construct(curve=curve_name, d=d, point_x=point_x, point_y=point_y)
def _import_private_der(encoded, passphrase, curve_name=None): # ECPrivateKey ::= SEQUENCE { # version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), # privateKey OCTET STRING, # parameters [0] ECParameters {{ NamedCurve }} OPTIONAL, # publicKey [1] BIT STRING OPTIONAL # } private_key = DerSequence().decode(encoded, nr_elements=(3, 4)) if private_key[0] != 1: raise ValueError("Incorrect ECC private key version") try: curve_name = DerObjectId(explicit=0).decode(private_key[2]).value except ValueError: pass if curve_name != _curve.oid: raise UnsupportedEccFeature("Unsupported ECC curve (OID: %s)" % curve_name) scalar_bytes = DerOctetString().decode(private_key[1]).payload order_bytes = _curve.order.size_in_bytes() if len(scalar_bytes) != order_bytes: raise ValueError("Private key is too small") d = Integer.from_bytes(scalar_bytes) # Decode public key (if any, it must be P-256) if len(private_key) == 4: public_key_enc = DerBitString(explicit=1).decode(private_key[3]).value public_key = _import_public_der(curve_name, public_key_enc) point_x = public_key.pointQ.x point_y = public_key.pointQ.y else: point_x = point_y = None return construct(curve="P-256", d=d, point_x=point_x, point_y=point_y)
def _import_subjectPublicKeyInfo(encoded, *kwargs): """Convert a subjectPublicKeyInfo into an EccKey object""" # See RFC5480 # Parse the generic subjectPublicKeyInfo structure oid, ec_point, params = _expand_subject_public_key_info(encoded) # ec_point must be an encoded OCTET STRING # params is encoded ECParameters # We accept id-ecPublicKey, id-ecDH, id-ecMQV without making any # distiction for now. # Restrictions can be captured in the key usage certificate # extension unrestricted_oid = "1.2.840.10045.2.1" ecdh_oid = "1.3.132.1.12" ecmqv_oid = "1.3.132.1.13" if oid not in (unrestricted_oid, ecdh_oid, ecmqv_oid): raise UnsupportedEccFeature("Unsupported ECC purpose (OID: %s)" % oid) # Parameters are mandatory for all three types if not params: raise ValueError("Missing ECC parameters") # ECParameters ::= CHOICE { # namedCurve OBJECT IDENTIFIER # -- implicitCurve NULL # -- specifiedCurve SpecifiedECDomain # } # # implicitCurve and specifiedCurve are not supported (as per RFC) curve_oid = DerObjectId().decode(params).value return _import_public_der(curve_oid, ec_point)
def _expand_subject_public_key_info(encoded): """Parse a SubjectPublicKeyInfo structure. It returns a triple with: * OID (string) * encoded public key (bytes) * Algorithm parameters (bytes or None) """ # # SubjectPublicKeyInfo ::= SEQUENCE { # algorithm AlgorithmIdentifier, # subjectPublicKey BIT STRING # } # # AlgorithmIdentifier ::= SEQUENCE { # algorithm OBJECT IDENTIFIER, # parameters ANY DEFINED BY algorithm OPTIONAL # } # spki = DerSequence().decode(encoded, nr_elements=2) algo = DerSequence().decode(spki[0], nr_elements=(1, 2)) algo_oid = DerObjectId().decode(algo[0]) spk = DerBitString().decode(spki[1]).value if len(algo) == 1: algo_params = None else: try: DerNull().decode(algo[1]) algo_params = None except: algo_params = algo[1] return algo_oid.value, spk, algo_params
def testDecode2(self): # Verify that decode returns the object der = DerObjectId() self.assertEqual( der, der.decode(b('\x06\x09\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01')))
def testDecode1(self): # Empty sequence der = DerObjectId() der.decode(b('\x06\x09\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01')) self.assertEqual(der.value, '1.2.840.113549.1.1.1')
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)) if len(pk_info) == 2 and not passphrase: raise ValueError("Not a valid clear PKCS#8 structure " "(maybe it is encrypted?)") # # PrivateKeyInfo ::= SEQUENCE { # version Version, # privateKeyAlgorithm PrivateKeyAlgorithmIdentifier, # privateKey PrivateKey, # attributes [0] IMPLICIT Attributes OPTIONAL # } # Version ::= INTEGER if pk_info[0] != 0: raise ValueError("Not a valid PrivateKeyInfo SEQUENCE") # PrivateKeyAlgorithmIdentifier ::= AlgorithmIdentifier # # EncryptedPrivateKeyInfo ::= SEQUENCE { # encryptionAlgorithm EncryptionAlgorithmIdentifier, # encryptedData EncryptedData # } # EncryptionAlgorithmIdentifier ::= AlgorithmIdentifier # AlgorithmIdentifier ::= SEQUENCE { # algorithm OBJECT IDENTIFIER, # parameters ANY DEFINED BY algorithm OPTIONAL # } 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] # EncryptedData ::= OCTET STRING private_key = DerOctetString().decode(pk_info[2]).payload return (algo_oid, private_key, algo_params)
def decrypt(data, passphrase): """Decrypt a piece of data using a passphrase and *PBES2*. The algorithm to use is automatically detected. :Parameters: data : byte string The piece of data to decrypt. passphrase : byte string The passphrase to use for decrypting the data. :Returns: The decrypted data, as a binary string. """ enc_private_key_info = DerSequence().decode(data, nr_elements=2) enc_algo = DerSequence().decode(enc_private_key_info[0]) encrypted_data = DerOctetString().decode( enc_private_key_info[1]).payload pbe_oid = DerObjectId().decode(enc_algo[0]).value if pbe_oid != "1.2.840.113549.1.5.13": raise PbesError("Not a PBES2 object") pbes2_params = DerSequence().decode(enc_algo[1], nr_elements=2) ### Key Derivation Function selection kdf_info = DerSequence().decode(pbes2_params[0], nr_elements=2) kdf_oid = DerObjectId().decode(kdf_info[0]).value # We only support PBKDF2 or scrypt if kdf_oid == "1.2.840.113549.1.5.12": pbkdf2_params = DerSequence().decode(kdf_info[1], nr_elements=(2, 3, 4)) salt = DerOctetString().decode(pbkdf2_params[0]).payload iteration_count = pbkdf2_params[1] if len(pbkdf2_params) > 2: kdf_key_length = pbkdf2_params[2] else: kdf_key_length = None if len(pbkdf2_params) > 3: raise PbesError("Unsupported PRF for PBKDF2") elif kdf_oid == "1.3.6.1.4.1.11591.4.11": scrypt_params = DerSequence().decode(kdf_info[1], nr_elements=(4, 5)) salt = DerOctetString().decode(scrypt_params[0]).payload iteration_count, scrypt_r, scrypt_p = [ scrypt_params[x] for x in (1, 2, 3) ] if len(scrypt_params) > 4: kdf_key_length = scrypt_params[4] else: kdf_key_length = None else: raise PbesError("Unsupported PBES2 KDF") ### Cipher selection enc_info = DerSequence().decode(pbes2_params[1]) enc_oid = DerObjectId().decode(enc_info[0]).value if enc_oid == "1.2.840.113549.3.7": # DES_EDE3_CBC ciphermod = DES3 key_size = 24 elif enc_oid == "2.16.840.1.101.3.4.1.2": # AES128_CBC ciphermod = AES key_size = 16 elif enc_oid == "2.16.840.1.101.3.4.1.22": # AES192_CBC ciphermod = AES key_size = 24 elif enc_oid == "2.16.840.1.101.3.4.1.42": # AES256_CBC ciphermod = AES key_size = 32 else: raise PbesError("Unsupported PBES2 cipher") if kdf_key_length and kdf_key_length != key_size: raise PbesError("Mismatch between PBES2 KDF parameters" " and selected cipher") IV = DerOctetString().decode(enc_info[1]).payload # Create cipher if kdf_oid == "1.2.840.113549.1.5.12": # PBKDF2 key = PBKDF2(passphrase, salt, key_size, iteration_count) else: key = scrypt(passphrase, salt, key_size, iteration_count, scrypt_r, scrypt_p) cipher = ciphermod.new(key, ciphermod.MODE_CBC, IV) # Decrypt data pt = cipher.decrypt(encrypted_data) return unpad(pt, cipher.block_size)
def encrypt(data, passphrase, protection, prot_params=None, randfunc=None): """Encrypt a piece of data using a passphrase and *PBES2*. :Parameters: data : byte string The piece of data to encrypt. passphrase : byte string The passphrase to use for encrypting the data. protection : string The identifier of the encryption algorithm to use. The default value is '``PBKDF2WithHMAC-SHA1AndDES-EDE3-CBC``'. prot_params : dictionary Parameters of 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 1 000. | | | The default value for scrypt is 16 384. | +------------------+-----------------------------------------------+ | 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. | +------------------+-----------------------------------------------+ 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 ``Crypto.Random``. :Returns: The encrypted data, as a binary string. """ if prot_params is None: prot_params = {} if randfunc is None: randfunc = Random.new().read if protection == 'PBKDF2WithHMAC-SHA1AndDES-EDE3-CBC': key_size = 24 module = DES3 cipher_mode = DES3.MODE_CBC enc_oid = "1.2.840.113549.3.7" elif protection in ('PBKDF2WithHMAC-SHA1AndAES128-CBC', 'scryptAndAES128-CBC'): key_size = 16 module = AES cipher_mode = AES.MODE_CBC enc_oid = "2.16.840.1.101.3.4.1.2" elif protection in ('PBKDF2WithHMAC-SHA1AndAES192-CBC', 'scryptAndAES192-CBC'): key_size = 24 module = AES cipher_mode = AES.MODE_CBC enc_oid = "2.16.840.1.101.3.4.1.22" elif protection in ('PBKDF2WithHMAC-SHA1AndAES256-CBC', 'scryptAndAES256-CBC'): key_size = 32 module = AES cipher_mode = AES.MODE_CBC enc_oid = "2.16.840.1.101.3.4.1.42" else: raise ValueError("Unknown PBES2 mode") # Get random data iv = randfunc(module.block_size) salt = randfunc(prot_params.get("salt_size", 8)) # Derive key from password if protection.startswith('PBKDF2'): count = prot_params.get("iteration_count", 1000) key = PBKDF2(passphrase, salt, key_size, count) kdf_info = DerSequence([ DerObjectId("1.2.840.113549.1.5.12"), # PBKDF2 DerSequence([DerOctetString(salt), DerInteger(count)]) ]) else: # It must be scrypt count = prot_params.get("iteration_count", 16384) scrypt_r = prot_params.get('block_size', 8) scrypt_p = prot_params.get('parallelization', 1) key = scrypt(passphrase, salt, key_size, count, scrypt_r, scrypt_p) kdf_info = DerSequence([ DerObjectId("1.3.6.1.4.1.11591.4.11"), # scrypt DerSequence([ DerOctetString(salt), DerInteger(count), DerInteger(scrypt_r), DerInteger(scrypt_p) ]) ]) # Create cipher and use it cipher = module.new(key, cipher_mode, iv) encrypted_data = cipher.encrypt(pad(data, cipher.block_size)) enc_info = DerSequence([DerObjectId(enc_oid), DerOctetString(iv)]) # Result enc_private_key_info = DerSequence([ # encryptionAlgorithm DerSequence([ DerObjectId("1.2.840.113549.1.5.13"), # PBES2 DerSequence([kdf_info, enc_info]), ]), DerOctetString(encrypted_data) ]) return enc_private_key_info.encode()
def _EMSA_PKCS1_V1_5_ENCODE(msg_hash, emLen, with_hash_parameters=True): """ Implement the ``EMSA-PKCS1-V1_5-ENCODE`` function, as defined in PKCS#1 v2.1 (RFC3447, 9.2). ``_EMSA-PKCS1-V1_5-ENCODE`` actually accepts the message ``M`` as input, and hash it internally. Here, we expect that the message has already been hashed instead. :Parameters: msg_hash : hash object The hash object that holds the digest of the message being signed. emLen : int The length the final encoding must have, in bytes. with_hash_parameters : bool If True (default), include NULL parameters for the hash algorithm in the ``digestAlgorithm`` SEQUENCE. :attention: the early standard (RFC2313) stated that ``DigestInfo`` had to be BER-encoded. This means that old signatures might have length tags in indefinite form, which is not supported in DER. Such encoding cannot be reproduced by this function. :Return: An ``emLen`` byte long string that encodes the hash. """ # First, build the ASN.1 DER object DigestInfo: # # DigestInfo ::= SEQUENCE { # digestAlgorithm AlgorithmIdentifier, # digest OCTET STRING # } # # where digestAlgorithm identifies the hash function and shall be an # algorithm ID with an OID in the set PKCS1-v1-5DigestAlgorithms. # # PKCS1-v1-5DigestAlgorithms ALGORITHM-IDENTIFIER ::= { # { OID id-md2 PARAMETERS NULL }| # { OID id-md5 PARAMETERS NULL }| # { OID id-sha1 PARAMETERS NULL }| # { OID id-sha256 PARAMETERS NULL }| # { OID id-sha384 PARAMETERS NULL }| # { OID id-sha512 PARAMETERS NULL } # } # # Appendix B.1 also says that for SHA-1/-2 algorithms, the parameters # should be omitted. They may be present, but when they are, they shall # have NULL value. digestAlgo = DerSequence([ DerObjectId(msg_hash.oid).encode() ]) if with_hash_parameters: digestAlgo.append(DerNull().encode()) digest = DerOctetString(msg_hash.digest()) digestInfo = DerSequence([ digestAlgo.encode(), digest.encode() ]).encode() # We need at least 11 bytes for the remaining data: 3 fixed bytes and # at least 8 bytes of padding). if emLen<len(digestInfo)+11: raise TypeError("Selected hash algorith has a too long digest (%d bytes)." % len(digest)) PS = bchr(0xFF) * (emLen - len(digestInfo) - 3) return b("\x00\x01") + PS + bchr(0x00) + digestInfo
def wrap(private_key, key_oid, passphrase=None, protection=None, prot_params=None, key_params=None, 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): The algorithm parameters associated to the private key. It is required for algorithms like DSA, but not for others like RSA. 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. """ if key_params is None: key_params = DerNull() # # PrivateKeyInfo ::= SEQUENCE { # version Version, # privateKeyAlgorithm PrivateKeyAlgorithmIdentifier, # privateKey PrivateKey, # attributes [0] IMPLICIT Attributes OPTIONAL # } # pk_info = DerSequence([ 0, DerSequence([DerObjectId(key_oid), key_params]), 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 testInit1(self): der = DerObjectId("1.1") self.assertEqual(der.encode(), b('\x06\x01)'))
def decrypt(data, passphrase): """Decrypt a piece of data using a passphrase and *PBES2*. The algorithm to use is automatically detected. :Parameters: data : byte string The piece of data to decrypt. passphrase : byte string The passphrase to use for decrypting the data. :Returns: The decrypted data, as a binary string. """ enc_private_key_info = DerSequence().decode(data, nr_elements=2) enc_algo = DerSequence().decode(enc_private_key_info[0]) encrypted_data = DerOctetString().decode( enc_private_key_info[1]).payload pbe_oid = DerObjectId().decode(enc_algo[0]).value if pbe_oid != _OID_PBES2: raise PbesError("Not a PBES2 object") pbes2_params = DerSequence().decode(enc_algo[1], nr_elements=2) ### Key Derivation Function selection kdf_info = DerSequence().decode(pbes2_params[0], nr_elements=2) kdf_oid = DerObjectId().decode(kdf_info[0]).value kdf_key_length = None # We only support PBKDF2 or scrypt if kdf_oid == _OID_PBKDF2: pbkdf2_params = DerSequence().decode(kdf_info[1], nr_elements=(2, 3, 4)) salt = DerOctetString().decode(pbkdf2_params[0]).payload iteration_count = pbkdf2_params[1] left = len(pbkdf2_params) - 2 idx = 2 if left > 0: try: kdf_key_length = pbkdf2_params[idx] - 0 left -= 1 idx += 1 except TypeError: pass # Default is HMAC-SHA1 pbkdf2_prf_oid = "1.2.840.113549.2.7" if left > 0: pbkdf2_prf_algo_id = DerSequence().decode(pbkdf2_params[idx]) pbkdf2_prf_oid = DerObjectId().decode( pbkdf2_prf_algo_id[0]).value elif kdf_oid == _OID_SCRYPT: scrypt_params = DerSequence().decode(kdf_info[1], nr_elements=(4, 5)) salt = DerOctetString().decode(scrypt_params[0]).payload iteration_count, scrypt_r, scrypt_p = [ scrypt_params[x] for x in (1, 2, 3) ] if len(scrypt_params) > 4: kdf_key_length = scrypt_params[4] else: kdf_key_length = None else: raise PbesError("Unsupported PBES2 KDF") ### Cipher selection enc_info = DerSequence().decode(pbes2_params[1]) enc_oid = DerObjectId().decode(enc_info[0]).value if enc_oid == _OID_DES_EDE3_CBC: # DES_EDE3_CBC ciphermod = DES3 key_size = 24 elif enc_oid == _OID_AES128_CBC: # AES128_CBC ciphermod = AES key_size = 16 elif enc_oid == _OID_AES192_CBC: # AES192_CBC ciphermod = AES key_size = 24 elif enc_oid == _OID_AES256_CBC: # AES256_CBC ciphermod = AES key_size = 32 else: raise PbesError("Unsupported PBES2 cipher") if kdf_key_length and kdf_key_length != key_size: raise PbesError("Mismatch between PBES2 KDF parameters" " and selected cipher") IV = DerOctetString().decode(enc_info[1]).payload # Create cipher if kdf_oid == _OID_PBKDF2: if pbkdf2_prf_oid == _OID_HMAC_SHA1: hmac_hash_module = SHA1 elif pbkdf2_prf_oid == _OID_HMAC_SHA224: hmac_hash_module = SHA224 elif pbkdf2_prf_oid == _OID_HMAC_SHA256: hmac_hash_module = SHA256 elif pbkdf2_prf_oid == _OID_HMAC_SHA384: hmac_hash_module = SHA384 elif pbkdf2_prf_oid == _OID_HMAC_SHA512: hmac_hash_module = SHA512 else: raise PbesError("Unsupported HMAC %s" % pbkdf2_prf_oid) key = PBKDF2(passphrase, salt, key_size, iteration_count, hmac_hash_module=hmac_hash_module) else: key = scrypt(passphrase, salt, key_size, iteration_count, scrypt_r, scrypt_p) cipher = ciphermod.new(key, ciphermod.MODE_CBC, IV) # Decrypt data pt = cipher.decrypt(encrypted_data) return unpad(pt, cipher.block_size)