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# Copyright (c) 2019-2021 by Ron Frederick <ronf@timeheart.net> and others.
#
# This program and the accompanying materials are made available under
# the terms of the Eclipse Public License v2.0 which accompanies this
# distribution and is available at:
#
# http://www.eclipse.org/legal/epl-2.0/
#
# This program may also be made available under the following secondary
# licenses when the conditions for such availability set forth in the
# Eclipse Public License v2.0 are satisfied:
#
# GNU General Public License, Version 2.0, or any later versions of
# that license
#
# SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
#
# Contributors:
# Ron Frederick - initial implementation, API, and documentation
"""EdDSA public key encryption handler"""
from typing import Optional, Tuple, Union, cast
from .asn1 import ASN1DecodeError, ObjectIdentifier, der_encode, der_decode
from .crypto import EdDSAPrivateKey, EdDSAPublicKey
from .crypto import ed25519_available, ed448_available
from .packet import String, SSHPacket
from .public_key import OMIT, SSHKey, SSHOpenSSHCertificateV01
from .public_key import KeyImportError, KeyExportError
from .public_key import register_public_key_alg, register_certificate_alg
from .public_key import register_x509_certificate_alg
_PrivateKeyArgs = Tuple[bytes]
_PublicKeyArgs = Tuple[bytes]
class _EdKey(SSHKey):
"""Handler for EdDSA public key encryption"""
_key: Union[EdDSAPrivateKey, EdDSAPublicKey]
algorithm = b''
def __eq__(self, other: object) -> bool:
# This isn't protected access - both objects are _EdKey instances
# pylint: disable=protected-access
return (isinstance(other, type(self)) and
self._key.public_value == other._key.public_value and
self._key.private_value == other._key.private_value)
def __hash__(self) -> int:
return hash((self._key.public_value, self._key.private_value))
@classmethod
def generate(cls, algorithm: bytes) -> '_EdKey': # type: ignore
"""Generate a new EdDSA private key"""
# pylint: disable=arguments-differ
# Strip 'ssh-' prefix of algorithm to get curve_id
return cls(EdDSAPrivateKey.generate(algorithm[4:]))
@classmethod
def make_private(cls, key_params: object) -> SSHKey:
"""Construct an EdDSA private key"""
try:
private_value, = cast(_PrivateKeyArgs, key_params)
return cls(EdDSAPrivateKey.construct(cls.algorithm[4:],
private_value))
except (TypeError, ValueError):
raise KeyImportError('Invalid EdDSA private key') from None
@classmethod
def make_public(cls, key_params: object) -> SSHKey:
"""Construct an EdDSA public key"""
try:
public_value, = cast(_PublicKeyArgs, key_params)
return cls(EdDSAPublicKey.construct(cls.algorithm[4:],
public_value))
except (TypeError, ValueError):
raise KeyImportError('Invalid EdDSA public key') from None
@classmethod
def decode_pkcs8_private(cls, alg_params: object,
data: bytes) -> Optional[_PrivateKeyArgs]:
"""Decode a PKCS#8 format EdDSA private key"""
# pylint: disable=unused-argument
try:
return (cast(bytes, der_decode(data)),)
except ASN1DecodeError:
return None
@classmethod
def decode_pkcs8_public(cls, alg_params: object,
data: bytes) -> Optional[_PublicKeyArgs]:
"""Decode a PKCS#8 format EdDSA public key"""
# pylint: disable=unused-argument
return (data,)
@classmethod
def decode_ssh_private(cls, packet: SSHPacket) -> _PrivateKeyArgs:
"""Decode an SSH format EdDSA private key"""
public_value = packet.get_string()
private_value = packet.get_string()
return (private_value[:-len(public_value)],)
@classmethod
def decode_ssh_public(cls, packet: SSHPacket) -> _PublicKeyArgs:
"""Decode an SSH format EdDSA public key"""
public_value = packet.get_string()
return (public_value,)
def encode_pkcs8_private(self) -> Tuple[object, object]:
"""Encode a PKCS#8 format EdDSA private key"""
if not self._key.private_value:
raise KeyExportError('Key is not private')
return OMIT, der_encode(self._key.private_value)
def encode_pkcs8_public(self) -> Tuple[object, object]:
"""Encode a PKCS#8 format EdDSA public key"""
return OMIT, self._key.public_value
def encode_ssh_private(self) -> bytes:
"""Encode an SSH format EdDSA private key"""
if self._key.private_value is None:
raise KeyExportError('Key is not private')
return b''.join((String(self._key.public_value),
String(self._key.private_value +
self._key.public_value)))
def encode_ssh_public(self) -> bytes:
"""Encode an SSH format EdDSA public key"""
return String(self._key.public_value)
def encode_agent_cert_private(self) -> bytes:
"""Encode EdDSA certificate private key data for agent"""
return self.encode_ssh_private()
def sign_ssh(self, data: bytes, sig_algorithm: bytes) -> bytes:
"""Compute an SSH-encoded signature of the specified data"""
# pylint: disable=unused-argument
if not self._key.private_value:
raise ValueError('Private key needed for signing')
return String(self._key.sign(data))
def verify_ssh(self, data: bytes, sig_algorithm: bytes,
packet: SSHPacket) -> bool:
"""Verify an SSH-encoded signature of the specified data"""
# pylint: disable=unused-argument
sig = packet.get_string()
packet.check_end()
return self._key.verify(data, sig)
class _Ed25519Key(_EdKey):
"""Handler for Curve25519 public key encryption"""
algorithm = b'ssh-ed25519'
pkcs8_oid = ObjectIdentifier('1.3.101.112')
sig_algorithms = (algorithm,)
x509_algorithms = (b'x509v3-' + algorithm,)
all_sig_algorithms = set(sig_algorithms)
class _Ed448Key(_EdKey):
"""Handler for Curve448 public key encryption"""
algorithm = b'ssh-ed448'
pkcs8_oid = ObjectIdentifier('1.3.101.113')
sig_algorithms = (algorithm,)
x509_algorithms = (b'x509v3-' + algorithm,)
all_sig_algorithms = set(sig_algorithms)
if ed25519_available: # pragma: no branch
register_public_key_alg(b'ssh-ed25519', _Ed25519Key, True)
register_certificate_alg(1, b'ssh-ed25519',
b'ssh-ed25519-cert-v01@openssh.com',
_Ed25519Key, SSHOpenSSHCertificateV01, True)
for alg in _Ed25519Key.x509_algorithms:
register_x509_certificate_alg(alg, True)
if ed448_available: # pragma: no branch
register_public_key_alg(b'ssh-ed448', _Ed448Key, True)
register_certificate_alg(1, b'ssh-ed448', b'ssh-ed448-cert-v01@openssh.com',
_Ed448Key, SSHOpenSSHCertificateV01, True)
for alg in _Ed448Key.x509_algorithms:
register_x509_certificate_alg(alg, True)
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