def _import_openssh_private_ecc(data, password):
from ._openssh import (import_openssh_private_generic, read_bytes,
read_string, check_padding)
ssh_name, decrypted = import_openssh_private_generic(data, password)
name, decrypted = read_string(decrypted)
if name not in _curves:
raise UnsupportedEccFeature("Unsupported ECC curve %s" % name)
curve = _curves[name]
modulus_bytes = (curve.modulus_bits + 7) // 8
public_key, decrypted = read_bytes(decrypted)
if bord(public_key[0]) != 4:
raise ValueError("Only uncompressed OpenSSH EC keys are supported")
if len(public_key) != 2 * modulus_bytes + 1:
raise ValueError("Incorrect public key length")
point_x = Integer.from_bytes(public_key[1:1 + modulus_bytes])
point_y = Integer.from_bytes(public_key[1 + modulus_bytes:])
point = EccPoint(point_x, point_y, curve=name)
private_key, decrypted = read_bytes(decrypted)
d = Integer.from_bytes(private_key)
_, padded = read_string(decrypted) # Comment
check_padding(padded)
return EccKey(curve=name, d=d, point=point)
def test_several_lengths(self):
prng = SHAKE128.new().update(b('Test'))
for length in range(1, 100):
base = Integer.from_bytes(prng.read(length))
modulus2 = Integer.from_bytes(prng.read(length)) | 1
exponent2 = Integer.from_bytes(prng.read(length))
expected = pow(base, exponent2, modulus2)
result = monty_pow(base, exponent2, modulus2)
self.assertEqual(result, expected)
def _generate_domain(L, randfunc):
"""Generate a new set of DSA domain parameters"""
N = {1024: 160, 2048: 224, 3072: 256}.get(L)
if N is None:
raise ValueError("Invalid modulus length (%d)" % L)
outlen = SHA256.digest_size * 8
n = (L + outlen - 1) // outlen - 1 # ceil(L/outlen) -1
b_ = L - 1 - (n * outlen)
# Generate q (A.1.1.2)
q = Integer(4)
upper_bit = 1 << (N - 1)
while test_probable_prime(q, randfunc) != PROBABLY_PRIME:
seed = randfunc(64)
U = Integer.from_bytes(SHA256.new(seed).digest()) & (upper_bit - 1)
q = U | upper_bit | 1
assert (q.size_in_bits() == N)
# Generate p (A.1.1.2)
offset = 1
upper_bit = 1 << (L - 1)
while True:
V = [
SHA256.new(seed + Integer(offset + j).to_bytes()).digest()
for j in iter_range(n + 1)
]
V = [Integer.from_bytes(v) for v in V]
W = sum([V[i] * (1 << (i * outlen)) for i in iter_range(n)],
(V[n] & ((1 << b_) - 1)) * (1 << (n * outlen)))
X = Integer(W + upper_bit) # 2^{L-1} < X < 2^{L}
assert (X.size_in_bits() == L)
c = X % (q * 2)
p = X - (c - 1) # 2q divides (p-1)
if p.size_in_bits() == L and \
test_probable_prime(p, randfunc) == PROBABLY_PRIME:
break
offset += n + 1
# Generate g (A.2.3, index=1)
e = (p - 1) // q
for count in itertools.count(1):
U = seed + b"ggen" + bchr(1) + Integer(count).to_bytes()
W = Integer.from_bytes(SHA256.new(U).digest())
g = pow(W, e, p)
if g != 1:
break
return (p, q, g, seed)
def verify(self, msg_hash, signature):
"""Check if a certain (EC)DSA signature is authentic.
:parameter msg_hash:
The hash that was carried out over the message.
This is an object belonging to the :mod:`crypto.Hash` module.
Under mode *'fips-186-3'*, the hash must be a FIPS
approved secure hash (SHA-1 or a member of the SHA-2 family),
of cryptographic strength appropriate for the DSA key.
For instance, a 3072/256 DSA key can only be used in
combination with SHA-512.
:type msg_hash: hash object
:parameter signature:
The signature that needs to be validated
:type signature: byte string
:raise ValueError: if the signature is not authentic
"""
if not self._valid_hash(msg_hash):
raise ValueError("Hash is not sufficiently strong")
if self._encoding == 'binary':
if len(signature) != (2 * self._order_bytes):
raise ValueError("The signature is not authentic (length)")
r_prime, s_prime = [
Integer.from_bytes(x) for x in (signature[:self._order_bytes],
signature[self._order_bytes:])
]
else:
try:
der_seq = DerSequence().decode(signature, strict=True)
except (ValueError, IndexError):
raise ValueError("The signature is not authentic (DER)")
if len(der_seq) != 2 or not der_seq.hasOnlyInts():
raise ValueError(
"The signature is not authentic (DER content)")
r_prime, s_prime = Integer(der_seq[0]), Integer(der_seq[1])
if not (0 < r_prime < self._order) or not (0 < s_prime < self._order):
raise ValueError("The signature is not authentic (d)")
z = Integer.from_bytes(msg_hash.digest()[:self._order_bytes])
result = self._key._verify(z, (r_prime, s_prime))
if not result:
raise ValueError("The signature is not authentic")
# Make PyCrypto code to fail
return False
def _import_public_der(curve_oid, ec_point):
"""Convert an encoded EC point into an EccKey object
curve_name: string with the OID of the curve
ec_point: byte string with the EC point (not DER encoded)
"""
for curve_name, curve in _curves.items():
if curve.oid == curve_oid:
break
else:
raise UnsupportedEccFeature("Unsupported ECC curve (OID: %s)" %
curve_oid)
# 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.
modulus_bytes = curve.p.size_in_bytes()
point_type = bord(ec_point[0])
# Uncompressed point
if point_type == 0x04:
if len(ec_point) != (1 + 2 * modulus_bytes):
raise ValueError("Incorrect EC point length")
x = Integer.from_bytes(ec_point[1:modulus_bytes + 1])
y = Integer.from_bytes(ec_point[modulus_bytes + 1:])
# Compressed point
elif point_type in (0x02, 0x3):
if len(ec_point) != (1 + modulus_bytes):
raise ValueError("Incorrect EC point length")
x = Integer.from_bytes(ec_point[1:])
y = (x**3 - x * 3 + curve.b).sqrt(curve.p) # Short Weierstrass
if point_type == 0x02 and y.is_odd():
y = curve.p - y
if point_type == 0x03 and y.is_even():
y = curve.p - y
else:
raise ValueError("Incorrect EC point encoding")
return construct(curve=curve_name, point_x=x, point_y=y)
def _bits2int(self, bstr):
"""See 2.3.2 in RFC6979"""
result = Integer.from_bytes(bstr)
q_len = self._order.size_in_bits()
b_len = len(bstr) * 8
if b_len > q_len:
result >>= (b_len - q_len)
return result
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 sign(self, msg_hash):
"""Produce the DSA/ECDSA signature of a message.
:parameter msg_hash:
The hash that was carried out over the message.
The object belongs to the :mod:`crypto.Hash` package.
Under mode *'fips-186-3'*, the hash must be a FIPS
approved secure hash (SHA-1 or a member of the SHA-2 family),
of cryptographic strength appropriate for the DSA key.
For instance, a 3072/256 DSA key can only be used
in combination with SHA-512.
:type msg_hash: hash object
:return: The signature as a *byte string*
:raise ValueError: if the hash algorithm is incompatible to the (EC)DSA key
:raise TypeError: if the (EC)DSA key has no private half
"""
if not self._valid_hash(msg_hash):
raise ValueError("Hash is not sufficiently strong")
# Generate the nonce k (critical!)
nonce = self._compute_nonce(msg_hash)
# Perform signature using the raw API
z = Integer.from_bytes(msg_hash.digest()[:self._order_bytes])
sig_pair = self._key._sign(z, nonce)
# Encode the signature into a single byte string
if self._encoding == 'binary':
output = b"".join(
[long_to_bytes(x, self._order_bytes) for x in sig_pair])
else:
# Dss-sig ::= SEQUENCE {
# r INTEGER,
# s INTEGER
# }
# Ecdsa-Sig-Value ::= SEQUENCE {
# r INTEGER,
# s INTEGER
# }
output = DerSequence(sig_pair).encode()
return output
def _import_openssh_private_rsa(data, password):
from ._openssh import (import_openssh_private_generic, read_bytes,
read_string, check_padding)
ssh_name, decrypted = import_openssh_private_generic(data, password)
if ssh_name != "ssh-rsa":
raise ValueError("This SSH key is not RSA")
n, decrypted = read_bytes(decrypted)
e, decrypted = read_bytes(decrypted)
d, decrypted = read_bytes(decrypted)
iqmp, decrypted = read_bytes(decrypted)
p, decrypted = read_bytes(decrypted)
q, decrypted = read_bytes(decrypted)
_, padded = read_string(decrypted) # Comment
check_padding(padded)
build = [Integer.from_bytes(x) for x in (n, e, d, q, p, iqmp)]
return construct(build)
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_key(extern_key, passphrase=None):
"""Import a DSA key.
Args:
extern_key (string or byte string):
The DSA key to import.
The following formats are supported for a DSA **public** key:
- X.509 certificate (binary DER or PEM)
- X.509 ``subjectPublicKeyInfo`` (binary DER or PEM)
- OpenSSH (ASCII one-liner, see `RFC4253`_)
The following formats are supported for a DSA **private** key:
- `PKCS#8`_ ``PrivateKeyInfo`` or ``EncryptedPrivateKeyInfo``
DER SEQUENCE (binary or PEM)
- OpenSSL/OpenSSH custom format (binary or PEM)
For details about the PEM encoding, see `RFC1421`_/`RFC1423`_.
passphrase (string):
In case of an encrypted private key, this is the pass phrase
from which the decryption key is derived.
Encryption may be applied either at the `PKCS#8`_ or at the PEM level.
Returns:
:class:`DsaKey` : a DSA key object
Raises:
ValueError : when the given key cannot be parsed (possibly because
the pass phrase is wrong).
.. _RFC1421: http://www.ietf.org/rfc/rfc1421.txt
.. _RFC1423: http://www.ietf.org/rfc/rfc1423.txt
.. _RFC4253: http://www.ietf.org/rfc/rfc4253.txt
.. _PKCS#8: http://www.ietf.org/rfc/rfc5208.txt
"""
extern_key = tobytes(extern_key)
if passphrase is not None:
passphrase = tobytes(passphrase)
if extern_key.startswith(b'-----'):
# This is probably a PEM encoded key
(der, marker, enc_flag) = PEM.decode(tostr(extern_key), passphrase)
if enc_flag:
passphrase = None
return _import_key_der(der, passphrase, None)
if extern_key.startswith(b'ssh-dss '):
# This is probably a public OpenSSH key
keystring = binascii.a2b_base64(extern_key.split(b' ')[1])
keyparts = []
while len(keystring) > 4:
length = struct.unpack(">I", keystring[:4])[0]
keyparts.append(keystring[4:4 + length])
keystring = keystring[4 + length:]
if keyparts[0] == b"ssh-dss":
tup = [Integer.from_bytes(keyparts[x]) for x in (4, 3, 1, 2)]
return construct(tup)
if len(extern_key) > 0 and bord(extern_key[0]) == 0x30:
# This is probably a DER encoded key
return _import_key_der(extern_key, passphrase, None)
raise ValueError("DSA key format is not supported")
def import_key(extern_key, passphrase=None):
"""Import an RSA key (public or private half), encoded in standard
form.
Args:
extern_key (string or byte string):
The RSA key to import.
The following formats are supported for an RSA **public key**:
- X.509 certificate (binary or PEM format)
- X.509 ``subjectPublicKeyInfo`` DER SEQUENCE (binary or PEM
encoding)
- `PKCS#1`_ ``RSAPublicKey`` DER SEQUENCE (binary or PEM encoding)
- OpenSSH (textual public key only)
The following formats are supported for an RSA **private key**:
- PKCS#1 ``RSAPrivateKey`` DER SEQUENCE (binary or PEM encoding)
- `PKCS#8`_ ``PrivateKeyInfo`` or ``EncryptedPrivateKeyInfo``
DER SEQUENCE (binary or PEM encoding)
- OpenSSH (textual public key only)
For details about the PEM encoding, see `RFC1421`_/`RFC1423`_.
The private key may be encrypted by means of a certain pass phrase
either at the PEM level or at the PKCS#8 level.
passphrase (string):
In case of an encrypted private key, this is the pass phrase from
which the decryption key is derived.
Returns: An RSA key object (:class:`RsaKey`).
Raises:
ValueError/IndexError/TypeError:
When the given key cannot be parsed (possibly because the pass
phrase is wrong).
.. _RFC1421: http://www.ietf.org/rfc/rfc1421.txt
.. _RFC1423: http://www.ietf.org/rfc/rfc1423.txt
.. _`PKCS#1`: http://www.ietf.org/rfc/rfc3447.txt
.. _`PKCS#8`: http://www.ietf.org/rfc/rfc5208.txt
"""
extern_key = tobytes(extern_key)
if passphrase is not None:
passphrase = tobytes(passphrase)
if extern_key.startswith(b('-----')):
# This is probably a PEM encoded key.
(der, marker, enc_flag) = PEM.decode(tostr(extern_key), passphrase)
if enc_flag:
passphrase = None
return _import_keyDER(der, passphrase)
if extern_key.startswith(b('ssh-rsa ')):
# This is probably an OpenSSH key
keystring = binascii.a2b_base64(extern_key.split(b(' '))[1])
keyparts = []
while len(keystring) > 4:
l = struct.unpack(">I", keystring[:4])[0]
keyparts.append(keystring[4:4 + l])
keystring = keystring[4 + l:]
e = Integer.from_bytes(keyparts[1])
n = Integer.from_bytes(keyparts[2])
return construct([n, e])
if bord(extern_key[0]) == 0x30:
# This is probably a DER encoded key
return _import_keyDER(extern_key, passphrase)
raise ValueError("RSA key format is not supported")
def import_key(extern_key, passphrase=None):
"""Import an RSA key (public or private).
Args:
extern_key (string or byte string):
The RSA key to import.
The following formats are supported for an RSA **public key**:
- X.509 certificate (binary or PEM format)
- X.509 ``subjectPublicKeyInfo`` DER SEQUENCE (binary or PEM
encoding)
- `PKCS#1`_ ``RSAPublicKey`` DER SEQUENCE (binary or PEM encoding)
- An OpenSSH line (e.g. the content of ``~/.ssh/id_ecdsa``, ASCII)
The following formats are supported for an RSA **private key**:
- PKCS#1 ``RSAPrivateKey`` DER SEQUENCE (binary or PEM encoding)
- `PKCS#8`_ ``PrivateKeyInfo`` or ``EncryptedPrivateKeyInfo``
DER SEQUENCE (binary or PEM encoding)
- OpenSSH (text format, introduced in `OpenSSH 6.5`_)
For details about the PEM encoding, see `RFC1421`_/`RFC1423`_.
passphrase (string or byte string):
For private keys only, the pass phrase that encrypts the key.
Returns: An RSA key object (:class:`RsaKey`).
Raises:
ValueError/IndexError/TypeError:
When the given key cannot be parsed (possibly because the pass
phrase is wrong).
.. _RFC1421: http://www.ietf.org/rfc/rfc1421.txt
.. _RFC1423: http://www.ietf.org/rfc/rfc1423.txt
.. _`PKCS#1`: http://www.ietf.org/rfc/rfc3447.txt
.. _`PKCS#8`: http://www.ietf.org/rfc/rfc5208.txt
.. _`OpenSSH 6.5`: https://flak.tedunangst.com/post/new-openssh-key-format-and-bcrypt-pbkdf
"""
from Crypto.IO import PEM
extern_key = tobytes(extern_key)
if passphrase is not None:
passphrase = tobytes(passphrase)
if extern_key.startswith(b'-----BEGIN OPENSSH PRIVATE KEY'):
text_encoded = tostr(extern_key)
openssh_encoded, marker, enc_flag = PEM.decode(text_encoded,
passphrase)
result = _import_openssh_private_rsa(openssh_encoded, passphrase)
return result
if extern_key.startswith(b'-----'):
# This is probably a PEM encoded key.
(der, marker, enc_flag) = PEM.decode(tostr(extern_key), passphrase)
if enc_flag:
passphrase = None
return _import_keyDER(der, passphrase)
if extern_key.startswith(b'ssh-rsa '):
# This is probably an OpenSSH key
keystring = binascii.a2b_base64(extern_key.split(b' ')[1])
keyparts = []
while len(keystring) > 4:
length = struct.unpack(">I", keystring[:4])[0]
keyparts.append(keystring[4:4 + length])
keystring = keystring[4 + length:]
e = Integer.from_bytes(keyparts[1])
n = Integer.from_bytes(keyparts[2])
return construct([n, e])
if len(extern_key) > 0 and bord(extern_key[0]) == 0x30:
# This is probably a DER encoded key
return _import_keyDER(extern_key, passphrase)
raise ValueError("RSA key format is not supported")
