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keys.py
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keys.py
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# -*- test-case-name: twisted.conch.test.test_keys -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Handling of RSA, DSA, ECDSA, and Ed25519 keys.
"""
from __future__ import annotations
import binascii
import struct
import unicodedata
import warnings
from base64 import b64encode, decodebytes, encodebytes
from hashlib import md5, sha256
from typing import Any
import bcrypt
from cryptography import utils
from cryptography.exceptions import InvalidSignature
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import dsa, ec, ed25519, padding, rsa
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives.serialization import (
load_pem_private_key,
load_ssh_public_key,
)
from typing_extensions import Literal
from twisted.conch.ssh import common, sexpy
from twisted.conch.ssh.common import int_to_bytes
from twisted.python import randbytes
from twisted.python.compat import iterbytes, nativeString
from twisted.python.constants import NamedConstant, Names
from twisted.python.deprecate import _mutuallyExclusiveArguments
try:
from cryptography.hazmat.primitives.asymmetric.utils import (
decode_dss_signature,
encode_dss_signature,
)
except ImportError:
from cryptography.hazmat.primitives.asymmetric.utils import ( # type: ignore[no-redef,attr-defined]
decode_rfc6979_signature as decode_dss_signature,
encode_rfc6979_signature as encode_dss_signature,
)
# Curve lookup table
_curveTable = {
b"ecdsa-sha2-nistp256": ec.SECP256R1(),
b"ecdsa-sha2-nistp384": ec.SECP384R1(),
b"ecdsa-sha2-nistp521": ec.SECP521R1(),
}
_secToNist = {
b"secp256r1": b"nistp256",
b"secp384r1": b"nistp384",
b"secp521r1": b"nistp521",
}
Ed25519PublicKey = ed25519.Ed25519PublicKey
Ed25519PrivateKey = ed25519.Ed25519PrivateKey
class BadKeyError(Exception):
"""
Raised when a key isn't what we expected from it.
XXX: we really need to check for bad keys
"""
class BadSignatureAlgorithmError(Exception):
"""
Raised when a public key signature algorithm name isn't defined for this
public key format.
"""
class EncryptedKeyError(Exception):
"""
Raised when an encrypted key is presented to fromString/fromFile without
a password.
"""
class BadFingerPrintFormat(Exception):
"""
Raises when unsupported fingerprint formats are presented to fingerprint.
"""
class FingerprintFormats(Names):
"""
Constants representing the supported formats of key fingerprints.
@cvar MD5_HEX: Named constant representing fingerprint format generated
using md5[RFC1321] algorithm in hexadecimal encoding.
@type MD5_HEX: L{twisted.python.constants.NamedConstant}
@cvar SHA256_BASE64: Named constant representing fingerprint format
generated using sha256[RFC4634] algorithm in base64 encoding
@type SHA256_BASE64: L{twisted.python.constants.NamedConstant}
"""
MD5_HEX = NamedConstant()
SHA256_BASE64 = NamedConstant()
class PassphraseNormalizationError(Exception):
"""
Raised when a passphrase contains Unicode characters that cannot be
normalized using the available Unicode character database.
"""
def _normalizePassphrase(passphrase):
"""
Normalize a passphrase, which may be Unicode.
If the passphrase is Unicode, this follows the requirements of U{NIST
800-63B, section
5.1.1.2<https://pages.nist.gov/800-63-3/sp800-63b.html#memsecretver>}
for Unicode characters in memorized secrets: it applies the
Normalization Process for Stabilized Strings using NFKC normalization.
The passphrase is then encoded using UTF-8.
@type passphrase: L{bytes} or L{unicode} or L{None}
@param passphrase: The passphrase to normalize.
@return: The normalized passphrase, if any.
@rtype: L{bytes} or L{None}
@raises PassphraseNormalizationError: if the passphrase is Unicode and
cannot be normalized using the available Unicode character database.
"""
if isinstance(passphrase, str):
# The Normalization Process for Stabilized Strings requires aborting
# with an error if the string contains any unassigned code point.
if any(unicodedata.category(c) == "Cn" for c in passphrase):
# Perhaps not very helpful, but we don't want to leak any other
# information about the passphrase.
raise PassphraseNormalizationError()
return unicodedata.normalize("NFKC", passphrase).encode("UTF-8")
else:
return passphrase
class Key:
"""
An object representing a key. A key can be either a public or
private key. A public key can verify a signature; a private key can
create or verify a signature. To generate a string that can be stored
on disk, use the toString method. If you have a private key, but want
the string representation of the public key, use Key.public().toString().
"""
@classmethod
def fromFile(cls, filename, type=None, passphrase=None):
"""
Load a key from a file.
@param filename: The path to load key data from.
@type type: L{str} or L{None}
@param type: A string describing the format the key data is in, or
L{None} to attempt detection of the type.
@type passphrase: L{bytes} or L{None}
@param passphrase: The passphrase the key is encrypted with, or L{None}
if there is no encryption.
@rtype: L{Key}
@return: The loaded key.
"""
with open(filename, "rb") as f:
return cls.fromString(f.read(), type, passphrase)
@classmethod
def fromString(cls, data, type=None, passphrase=None):
"""
Return a Key object corresponding to the string data.
type is optionally the type of string, matching a _fromString_*
method. Otherwise, the _guessStringType() classmethod will be used
to guess a type. If the key is encrypted, passphrase is used as
the decryption key.
@type data: L{bytes}
@param data: The key data.
@type type: L{str} or L{None}
@param type: A string describing the format the key data is in, or
L{None} to attempt detection of the type.
@type passphrase: L{bytes} or L{None}
@param passphrase: The passphrase the key is encrypted with, or L{None}
if there is no encryption.
@rtype: L{Key}
@return: The loaded key.
"""
if isinstance(data, str):
data = data.encode("utf-8")
passphrase = _normalizePassphrase(passphrase)
if type is None:
type = cls._guessStringType(data)
if type is None:
raise BadKeyError(f"cannot guess the type of {data!r}")
method = getattr(cls, f"_fromString_{type.upper()}", None)
if method is None:
raise BadKeyError(f"no _fromString method for {type}")
if method.__code__.co_argcount == 2: # No passphrase
if passphrase:
raise BadKeyError("key not encrypted")
return method(data)
else:
return method(data, passphrase)
@classmethod
def _fromString_BLOB(cls, blob):
"""
Return a public key object corresponding to this public key blob.
The format of a RSA public key blob is::
string 'ssh-rsa'
integer e
integer n
The format of a DSA public key blob is::
string 'ssh-dss'
integer p
integer q
integer g
integer y
The format of ECDSA-SHA2-* public key blob is::
string 'ecdsa-sha2-[identifier]'
integer x
integer y
identifier is the standard NIST curve name.
The format of an Ed25519 public key blob is::
string 'ssh-ed25519'
string a
@type blob: L{bytes}
@param blob: The key data.
@return: A new key.
@rtype: L{twisted.conch.ssh.keys.Key}
@raises BadKeyError: if the key type (the first string) is unknown.
"""
keyType, rest = common.getNS(blob)
if keyType == b"ssh-rsa":
e, n, rest = common.getMP(rest, 2)
return cls(rsa.RSAPublicNumbers(e, n).public_key(default_backend()))
elif keyType == b"ssh-dss":
p, q, g, y, rest = common.getMP(rest, 4)
return cls(
dsa.DSAPublicNumbers(
y=y, parameter_numbers=dsa.DSAParameterNumbers(p=p, q=q, g=g)
).public_key(default_backend())
)
elif keyType in _curveTable:
return cls(
ec.EllipticCurvePublicKey.from_encoded_point(
_curveTable[keyType], common.getNS(rest, 2)[1]
)
)
elif keyType == b"ssh-ed25519":
a, rest = common.getNS(rest)
return cls._fromEd25519Components(a)
else:
raise BadKeyError(f"unknown blob type: {keyType}")
@classmethod
def _fromString_PRIVATE_BLOB(cls, blob):
"""
Return a private key object corresponding to this private key blob.
The blob formats are as follows:
RSA keys::
string 'ssh-rsa'
integer n
integer e
integer d
integer u
integer p
integer q
DSA keys::
string 'ssh-dss'
integer p
integer q
integer g
integer y
integer x
EC keys::
string 'ecdsa-sha2-[identifier]'
string identifier
string q
integer privateValue
identifier is the standard NIST curve name.
Ed25519 keys::
string 'ssh-ed25519'
string a
string k || a
@type blob: L{bytes}
@param blob: The key data.
@return: A new key.
@rtype: L{twisted.conch.ssh.keys.Key}
@raises BadKeyError: if
* the key type (the first string) is unknown
* the curve name of an ECDSA key does not match the key type
"""
keyType, rest = common.getNS(blob)
if keyType == b"ssh-rsa":
n, e, d, u, p, q, rest = common.getMP(rest, 6)
return cls._fromRSAComponents(n=n, e=e, d=d, p=p, q=q)
elif keyType == b"ssh-dss":
p, q, g, y, x, rest = common.getMP(rest, 5)
return cls._fromDSAComponents(y=y, g=g, p=p, q=q, x=x)
elif keyType in _curveTable:
curve = _curveTable[keyType]
curveName, q, rest = common.getNS(rest, 2)
if curveName != _secToNist[curve.name.encode("ascii")]:
raise BadKeyError(
"ECDSA curve name %r does not match key "
"type %r" % (curveName, keyType)
)
privateValue, rest = common.getMP(rest)
return cls._fromECEncodedPoint(
encodedPoint=q, curve=keyType, privateValue=privateValue
)
elif keyType == b"ssh-ed25519":
# OpenSSH's format repeats the public key bytes for some reason.
# We're only interested in the private key here anyway.
a, combined, rest = common.getNS(rest, 2)
k = combined[:32]
return cls._fromEd25519Components(a, k=k)
else:
raise BadKeyError(f"unknown blob type: {keyType}")
@classmethod
def _fromString_PUBLIC_OPENSSH(cls, data):
"""
Return a public key object corresponding to this OpenSSH public key
string. The format of an OpenSSH public key string is::
<key type> <base64-encoded public key blob>
@type data: L{bytes}
@param data: The key data.
@return: A new key.
@rtype: L{twisted.conch.ssh.keys.Key}
@raises BadKeyError: if the blob type is unknown.
"""
# ECDSA keys don't need base64 decoding which is required
# for RSA or DSA key.
if data.startswith(b"ecdsa-sha2"):
return cls(load_ssh_public_key(data, default_backend()))
blob = decodebytes(data.split()[1])
return cls._fromString_BLOB(blob)
@classmethod
def _fromPrivateOpenSSH_v1(cls, data, passphrase):
"""
Return a private key object corresponding to this OpenSSH private key
string, in the "openssh-key-v1" format introduced in OpenSSH 6.5.
The format of an openssh-key-v1 private key string is::
-----BEGIN OPENSSH PRIVATE KEY-----
<base64-encoded SSH protocol string>
-----END OPENSSH PRIVATE KEY-----
The SSH protocol string is as described in
U{PROTOCOL.key<https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/PROTOCOL.key>}.
@type data: L{bytes}
@param data: The key data.
@type passphrase: L{bytes} or L{None}
@param passphrase: The passphrase the key is encrypted with, or L{None}
if it is not encrypted.
@return: A new key.
@rtype: L{twisted.conch.ssh.keys.Key}
@raises BadKeyError: if
* a passphrase is provided for an unencrypted key
* the SSH protocol encoding is incorrect
@raises EncryptedKeyError: if
* a passphrase is not provided for an encrypted key
"""
lines = data.strip().splitlines()
keyList = decodebytes(b"".join(lines[1:-1]))
if not keyList.startswith(b"openssh-key-v1\0"):
raise BadKeyError("unknown OpenSSH private key format")
keyList = keyList[len(b"openssh-key-v1\0") :]
cipher, kdf, kdfOptions, rest = common.getNS(keyList, 3)
n = struct.unpack("!L", rest[:4])[0]
if n != 1:
raise BadKeyError(
"only OpenSSH private key files containing "
"a single key are supported"
)
# Ignore public key
_, encPrivKeyList, _ = common.getNS(rest[4:], 2)
if cipher != b"none":
if not passphrase:
raise EncryptedKeyError(
"Passphrase must be provided " "for an encrypted key"
)
# Determine cipher
if cipher in (b"aes128-ctr", b"aes192-ctr", b"aes256-ctr"):
algorithmClass = algorithms.AES
blockSize = 16
keySize = int(cipher[3:6]) // 8
ivSize = blockSize
else:
raise BadKeyError(f"unknown encryption type {cipher!r}")
if kdf == b"bcrypt":
salt, rest = common.getNS(kdfOptions)
rounds = struct.unpack("!L", rest[:4])[0]
decKey = bcrypt.kdf(
passphrase,
salt,
keySize + ivSize,
rounds,
# We can only use the number of rounds that OpenSSH used.
ignore_few_rounds=True,
)
else:
raise BadKeyError(f"unknown KDF type {kdf!r}")
if (len(encPrivKeyList) % blockSize) != 0:
raise BadKeyError("bad padding")
decryptor = Cipher(
algorithmClass(decKey[:keySize]),
modes.CTR(decKey[keySize : keySize + ivSize]),
backend=default_backend(),
).decryptor()
privKeyList = decryptor.update(encPrivKeyList) + decryptor.finalize()
else:
if kdf != b"none":
raise BadKeyError(
"private key specifies KDF %r but no " "cipher" % (kdf,)
)
privKeyList = encPrivKeyList
check1 = struct.unpack("!L", privKeyList[:4])[0]
check2 = struct.unpack("!L", privKeyList[4:8])[0]
if check1 != check2:
raise BadKeyError("check values do not match: %d != %d" % (check1, check2))
return cls._fromString_PRIVATE_BLOB(privKeyList[8:])
@classmethod
def _fromPrivateOpenSSH_PEM(cls, data, passphrase):
"""
Return a private key object corresponding to this OpenSSH private key
string, in the old PEM-based format.
The format of a PEM-based OpenSSH private key string is::
-----BEGIN <key type> PRIVATE KEY-----
[Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,<initialization value>]
<base64-encoded ASN.1 structure>
------END <key type> PRIVATE KEY------
The ASN.1 structure of a RSA key is::
(0, n, e, d, p, q)
The ASN.1 structure of a DSA key is::
(0, p, q, g, y, x)
The ASN.1 structure of a ECDSA key is::
(ECParameters, OID, NULL)
@type data: L{bytes}
@param data: The key data.
@type passphrase: L{bytes} or L{None}
@param passphrase: The passphrase the key is encrypted with, or L{None}
if it is not encrypted.
@return: A new key.
@rtype: L{twisted.conch.ssh.keys.Key}
@raises BadKeyError: if
* a passphrase is provided for an unencrypted key
* the ASN.1 encoding is incorrect
@raises EncryptedKeyError: if
* a passphrase is not provided for an encrypted key
"""
lines = data.strip().splitlines()
kind = lines[0][11:-17]
# cryptography considers an empty byte string a passphrase, but
# twisted considers that to be "no password". So we need to convert
# to None on empty.
if not passphrase:
passphrase = None
if kind in (b"EC", b"RSA", b"DSA"):
try:
key = load_pem_private_key(data, passphrase, default_backend())
except TypeError:
raise EncryptedKeyError(
"Passphrase must be provided for an encrypted key"
)
except ValueError:
raise BadKeyError("Failed to decode key (Bad Passphrase?)")
return cls(key)
else:
raise BadKeyError(f"unknown key type {kind}")
@classmethod
def _fromString_PRIVATE_OPENSSH(cls, data, passphrase):
"""
Return a private key object corresponding to this OpenSSH private key
string. If the key is encrypted, passphrase MUST be provided.
Providing a passphrase for an unencrypted key is an error.
@type data: L{bytes}
@param data: The key data.
@type passphrase: L{bytes} or L{None}
@param passphrase: The passphrase the key is encrypted with, or L{None}
if it is not encrypted.
@return: A new key.
@rtype: L{twisted.conch.ssh.keys.Key}
@raises BadKeyError: if
* a passphrase is provided for an unencrypted key
* the encoding is incorrect
@raises EncryptedKeyError: if
* a passphrase is not provided for an encrypted key
"""
if data.strip().splitlines()[0][11:-17] == b"OPENSSH":
# New-format (openssh-key-v1) key
return cls._fromPrivateOpenSSH_v1(data, passphrase)
else:
# Old-format (PEM) key
return cls._fromPrivateOpenSSH_PEM(data, passphrase)
@classmethod
def _fromString_PUBLIC_LSH(cls, data):
"""
Return a public key corresponding to this LSH public key string.
The LSH public key string format is::
<s-expression: ('public-key', (<key type>, (<name, <value>)+))>
The names for a RSA (key type 'rsa-pkcs1-sha1') key are: n, e.
The names for a DSA (key type 'dsa') key are: y, g, p, q.
@type data: L{bytes}
@param data: The key data.
@return: A new key.
@rtype: L{twisted.conch.ssh.keys.Key}
@raises BadKeyError: if the key type is unknown
"""
sexp = sexpy.parse(decodebytes(data[1:-1]))
assert sexp[0] == b"public-key"
kd = {}
for name, data in sexp[1][1:]:
kd[name] = common.getMP(common.NS(data))[0]
if sexp[1][0] == b"dsa":
return cls._fromDSAComponents(
y=kd[b"y"], g=kd[b"g"], p=kd[b"p"], q=kd[b"q"]
)
elif sexp[1][0] == b"rsa-pkcs1-sha1":
return cls._fromRSAComponents(n=kd[b"n"], e=kd[b"e"])
else:
raise BadKeyError(f"unknown lsh key type {sexp[1][0]}")
@classmethod
def _fromString_PRIVATE_LSH(cls, data):
"""
Return a private key corresponding to this LSH private key string.
The LSH private key string format is::
<s-expression: ('private-key', (<key type>, (<name>, <value>)+))>
The names for a RSA (key type 'rsa-pkcs1-sha1') key are: n, e, d, p, q.
The names for a DSA (key type 'dsa') key are: y, g, p, q, x.
@type data: L{bytes}
@param data: The key data.
@return: A new key.
@rtype: L{twisted.conch.ssh.keys.Key}
@raises BadKeyError: if the key type is unknown
"""
sexp = sexpy.parse(data)
assert sexp[0] == b"private-key"
kd = {}
for name, data in sexp[1][1:]:
kd[name] = common.getMP(common.NS(data))[0]
if sexp[1][0] == b"dsa":
assert len(kd) == 5, len(kd)
return cls._fromDSAComponents(
y=kd[b"y"], g=kd[b"g"], p=kd[b"p"], q=kd[b"q"], x=kd[b"x"]
)
elif sexp[1][0] == b"rsa-pkcs1":
assert len(kd) == 8, len(kd)
if kd[b"p"] > kd[b"q"]: # Make p smaller than q
kd[b"p"], kd[b"q"] = kd[b"q"], kd[b"p"]
return cls._fromRSAComponents(
n=kd[b"n"], e=kd[b"e"], d=kd[b"d"], p=kd[b"p"], q=kd[b"q"]
)
else:
raise BadKeyError(f"unknown lsh key type {sexp[1][0]}")
@classmethod
def _fromString_AGENTV3(cls, data):
"""
Return a private key object corresponsing to the Secure Shell Key
Agent v3 format.
The SSH Key Agent v3 format for a RSA key is::
string 'ssh-rsa'
integer e
integer d
integer n
integer u
integer p
integer q
The SSH Key Agent v3 format for a DSA key is::
string 'ssh-dss'
integer p
integer q
integer g
integer y
integer x
@type data: L{bytes}
@param data: The key data.
@return: A new key.
@rtype: L{twisted.conch.ssh.keys.Key}
@raises BadKeyError: if the key type (the first string) is unknown
"""
keyType, data = common.getNS(data)
if keyType == b"ssh-dss":
p, data = common.getMP(data)
q, data = common.getMP(data)
g, data = common.getMP(data)
y, data = common.getMP(data)
x, data = common.getMP(data)
return cls._fromDSAComponents(y=y, g=g, p=p, q=q, x=x)
elif keyType == b"ssh-rsa":
e, data = common.getMP(data)
d, data = common.getMP(data)
n, data = common.getMP(data)
u, data = common.getMP(data)
p, data = common.getMP(data)
q, data = common.getMP(data)
return cls._fromRSAComponents(n=n, e=e, d=d, p=p, q=q, u=u)
else:
raise BadKeyError(f"unknown key type {keyType}")
@classmethod
def _guessStringType(cls, data):
"""
Guess the type of key in data. The types map to _fromString_*
methods.
@type data: L{bytes}
@param data: The key data.
"""
if data.startswith(b"ssh-") or data.startswith(b"ecdsa-sha2-"):
return "public_openssh"
elif data.startswith(b"-----BEGIN"):
return "private_openssh"
elif data.startswith(b"{"):
return "public_lsh"
elif data.startswith(b"("):
return "private_lsh"
elif (
data.startswith(b"\x00\x00\x00\x07ssh-")
or data.startswith(b"\x00\x00\x00\x13ecdsa-")
or data.startswith(b"\x00\x00\x00\x0bssh-ed25519")
):
ignored, rest = common.getNS(data)
count = 0
while rest:
count += 1
ignored, rest = common.getMP(rest)
if count > 4:
return "agentv3"
else:
return "blob"
@classmethod
def _fromRSAComponents(cls, n, e, d=None, p=None, q=None, u=None):
"""
Build a key from RSA numerical components.
@type n: L{int}
@param n: The 'n' RSA variable.
@type e: L{int}
@param e: The 'e' RSA variable.
@type d: L{int} or L{None}
@param d: The 'd' RSA variable (optional for a public key).
@type p: L{int} or L{None}
@param p: The 'p' RSA variable (optional for a public key).
@type q: L{int} or L{None}
@param q: The 'q' RSA variable (optional for a public key).
@type u: L{int} or L{None}
@param u: The 'u' RSA variable. Ignored, as its value is determined by
p and q.
@rtype: L{Key}
@return: An RSA key constructed from the values as given.
"""
publicNumbers = rsa.RSAPublicNumbers(e=e, n=n)
if d is None:
# We have public components.
keyObject = publicNumbers.public_key(default_backend())
else:
privateNumbers = rsa.RSAPrivateNumbers(
p=p,
q=q,
d=d,
dmp1=rsa.rsa_crt_dmp1(d, p),
dmq1=rsa.rsa_crt_dmq1(d, q),
iqmp=rsa.rsa_crt_iqmp(p, q),
public_numbers=publicNumbers,
)
keyObject = privateNumbers.private_key(default_backend())
return cls(keyObject)
@classmethod
def _fromDSAComponents(cls, y, p, q, g, x=None):
"""
Build a key from DSA numerical components.
@type y: L{int}
@param y: The 'y' DSA variable.
@type p: L{int}
@param p: The 'p' DSA variable.
@type q: L{int}
@param q: The 'q' DSA variable.
@type g: L{int}
@param g: The 'g' DSA variable.
@type x: L{int} or L{None}
@param x: The 'x' DSA variable (optional for a public key)
@rtype: L{Key}
@return: A DSA key constructed from the values as given.
"""
publicNumbers = dsa.DSAPublicNumbers(
y=y, parameter_numbers=dsa.DSAParameterNumbers(p=p, q=q, g=g)
)
if x is None:
# We have public components.
keyObject = publicNumbers.public_key(default_backend())
else:
privateNumbers = dsa.DSAPrivateNumbers(x=x, public_numbers=publicNumbers)
keyObject = privateNumbers.private_key(default_backend())
return cls(keyObject)
@classmethod
def _fromECComponents(cls, x, y, curve, privateValue=None):
"""
Build a key from EC components.
@param x: The affine x component of the public point used for verifying.
@type x: L{int}
@param y: The affine y component of the public point used for verifying.
@type y: L{int}
@param curve: NIST name of elliptic curve.
@type curve: L{bytes}
@param privateValue: The private value.
@type privateValue: L{int}
"""
publicNumbers = ec.EllipticCurvePublicNumbers(
x=x, y=y, curve=_curveTable[curve]
)
if privateValue is None:
# We have public components.
keyObject = publicNumbers.public_key(default_backend())
else:
privateNumbers = ec.EllipticCurvePrivateNumbers(
private_value=privateValue, public_numbers=publicNumbers
)
keyObject = privateNumbers.private_key(default_backend())
return cls(keyObject)
@classmethod
def _fromECEncodedPoint(cls, encodedPoint, curve, privateValue=None):
"""
Build a key from an EC encoded point.
@param encodedPoint: The public point encoded as in SEC 1 v2.0
section 2.3.3.
@type encodedPoint: L{bytes}
@param curve: NIST name of elliptic curve.
@type curve: L{bytes}
@param privateValue: The private value.
@type privateValue: L{int}
"""
if privateValue is None:
# We have public components.
keyObject = ec.EllipticCurvePublicKey.from_encoded_point(
_curveTable[curve], encodedPoint
)
else:
keyObject = ec.derive_private_key(
privateValue, _curveTable[curve], default_backend()
)
return cls(keyObject)
@classmethod
def _fromEd25519Components(cls, a, k=None):
"""Build a key from Ed25519 components.
@param a: The Ed25519 public key, as defined in RFC 8032 section
5.1.5.
@type a: L{bytes}
@param k: The Ed25519 private key, as defined in RFC 8032 section
5.1.5.
@type k: L{bytes}
"""
if Ed25519PublicKey is None or Ed25519PrivateKey is None:
raise BadKeyError("Ed25519 keys not supported on this system")
if k is None:
keyObject = Ed25519PublicKey.from_public_bytes(a)
else:
keyObject = Ed25519PrivateKey.from_private_bytes(k)
return cls(keyObject)
def __init__(self, keyObject):
"""
Initialize with a private or public
C{cryptography.hazmat.primitives.asymmetric} key.
@param keyObject: Low level key.
@type keyObject: C{cryptography.hazmat.primitives.asymmetric} key.
"""
self._keyObject = keyObject
def __eq__(self, other: object) -> bool:
"""
Return True if other represents an object with the same key.
"""
if isinstance(other, Key):
return self.type() == other.type() and self.data() == other.data()
else:
return NotImplemented
def __repr__(self) -> str:
"""
Return a pretty representation of this object.
"""
if self.type() == "EC":
data = self.data()
name = data["curve"].decode("utf-8")
if self.isPublic():
out = f"<Elliptic Curve Public Key ({name[-3:]} bits)"
else:
out = f"<Elliptic Curve Private Key ({name[-3:]} bits)"
for k, v in sorted(data.items()):
if k == "curve":
out += f"\ncurve:\n\t{name}"
else:
out += f"\n{k}:\n\t{v}"
return out + ">\n"
else:
lines = [
"<%s %s (%s bits)"
% (
nativeString(self.type()),
self.isPublic() and "Public Key" or "Private Key",
self.size(),
)
]
for k, v in sorted(self.data().items()):
lines.append(f"attr {k}:")
by = v if self.type() == "Ed25519" else common.MP(v)[4:]
while by:
m = by[:15]
by = by[15:]
o = ""
for c in iterbytes(m):
o = o + f"{ord(c):02x}:"
if len(m) < 15:
o = o[:-1]
lines.append("\t" + o)
lines[-1] = lines[-1] + ">"
return "\n".join(lines)
def isPublic(self):
"""
Check if this instance is a public key.
@return: C{True} if this is a public key.
"""
return isinstance(
self._keyObject,
(
rsa.RSAPublicKey,
dsa.DSAPublicKey,
ec.EllipticCurvePublicKey,
ed25519.Ed25519PublicKey,
),
)
def public(self):
"""
Returns a version of this key containing only the public key data.
If this is a public key, this may or may not be the same object
as self.
@rtype: L{Key}
@return: A public key.
"""
if self.isPublic():
return self
else:
return Key(self._keyObject.public_key())
def fingerprint(self, format=FingerprintFormats.MD5_HEX):
"""
The fingerprint of a public key consists of the output of the
message-digest algorithm in the specified format.
Supported formats include L{FingerprintFormats.MD5_HEX} and
L{FingerprintFormats.SHA256_BASE64}
The input to the algorithm is the public key data as specified by [RFC4253].
The output of sha256[RFC4634] algorithm is presented to the
user in the form of base64 encoded sha256 hashes.
Example: C{US5jTUa0kgX5ZxdqaGF0yGRu8EgKXHNmoT8jHKo1StM=}
The output of the MD5[RFC1321](default) algorithm is presented to the user as
a sequence of 16 octets printed as hexadecimal with lowercase letters
and separated by colons.
Example: C{c1:b1:30:29:d7:b8:de:6c:97:77:10:d7:46:41:63:87}
@param format: Format for fingerprint generation. Consists
hash function and representation format.
Default is L{FingerprintFormats.MD5_HEX}
@since: 8.2
@return: the user presentation of this L{Key}'s fingerprint, as a
string.
@rtype: L{str}
"""
if format is FingerprintFormats.SHA256_BASE64:
return nativeString(b64encode(sha256(self.blob()).digest()))
elif format is FingerprintFormats.MD5_HEX:
return nativeString(
b":".join(
[binascii.hexlify(x) for x in iterbytes(md5(self.blob()).digest())]
)
)
else:
raise BadFingerPrintFormat(f"Unsupported fingerprint format: {format}")
def type(self) -> Literal["RSA", "DSA", "EC", "Ed25519"]:
"""
Return the type of the object we wrap. Currently this can only be
'RSA', 'DSA', 'EC', or 'Ed25519'.