diff options
Diffstat (limited to 'frozen_deps/ecdsa/keys.py')
| -rw-r--r-- | frozen_deps/ecdsa/keys.py | 829 |
1 files changed, 494 insertions, 335 deletions
diff --git a/frozen_deps/ecdsa/keys.py b/frozen_deps/ecdsa/keys.py index a6fc13f..2b7d316 100644 --- a/frozen_deps/ecdsa/keys.py +++ b/frozen_deps/ecdsa/keys.py @@ -1,80 +1,16 @@ """ Primary classes for performing signing and verification operations. - -.. glossary:: - - raw encoding - Conversion of public, private keys and signatures (which in - mathematical sense are integers or pairs of integers) to strings of - bytes that does not use any special tags or encoding rules. - For any given curve, all keys of the same type or signatures will be - encoded to byte strings of the same length. In more formal sense, - the integers are encoded as big-endian, constant length byte strings, - where the string length is determined by the curve order (e.g. - for NIST256p the order is 256 bits long, so the private key will be 32 - bytes long while public key will be 64 bytes long). The encoding of a - single integer is zero-padded on the left if the numerical value is - low. In case of public keys and signatures, which are comprised of two - integers, the integers are simply concatenated. - - uncompressed - The most common formatting specified in PKIX standards. Specified in - X9.62 and SEC1 standards. The only difference between it and - :term:`raw encoding` is the prepending of a 0x04 byte. Thus an - uncompressed NIST256p public key encoding will be 65 bytes long. - - compressed - The public point representation that uses half of bytes of the - :term:`uncompressed` encoding (rounded up). It uses the first byte of - the encoding to specify the sign of the y coordinate and encodes the - x coordinate as-is. The first byte of the encoding is equal to - 0x02 or 0x03. Compressed encoding of NIST256p public key will be 33 - bytes long. - - hybrid - A combination of :term:`uncompressed` and :term:`compressed` encodings. - Both x and y coordinates are stored just as in :term:`compressed` - encoding, but the first byte reflects the sign of the y coordinate. The - first byte of the encoding will be equal to 0x06 or 0x7. Hybrid - encoding of NIST256p public key will be 65 bytes long. - - PEM - The acronym stands for Privacy Enhanced Email, but currently it is used - primarily as the way to encode :term:`DER` objects into text that can - be either easily copy-pasted or transferred over email. - It uses headers like ``-----BEGIN <type of contents>-----`` and footers - like ``-----END <type of contents>-----`` to separate multiple - types of objects in the same file or the object from the surrounding - comments. The actual object stored is base64 encoded. - - DER - Distinguished Encoding Rules, the way to encode :term:`ASN.1` objects - deterministically and uniquely into byte strings. - - ASN.1 - Abstract Syntax Notation 1 is a standard description language for - specifying serialisation and deserialisation of data structures in a - portable and cross-platform way. - - bytes-like object - All the types that implement the buffer protocol. That includes - ``str`` (only on python2), ``bytes``, ``bytesarray``, ``array.array` - and ``memoryview`` of those objects. - Please note that ``array.array` serialisation (converting it to byte - string) is endianess dependant! Signature computed over ``array.array`` - of integers on a big-endian system will not be verified on a - little-endian system and vice-versa. """ import binascii from hashlib import sha1 +import os from six import PY2, b -from . import ecdsa +from . import ecdsa, eddsa from . import der from . import rfc6979 from . import ellipticcurve -from .curves import NIST192p, find_curve -from .numbertheory import square_root_mod_prime, SquareRootError +from .curves import NIST192p, Curve, Ed25519, Ed448 from .ecdsa import RSZeroError from .util import string_to_number, number_to_string, randrange from .util import sigencode_string, sigdecode_string, bit_length @@ -86,6 +22,8 @@ from .util import ( MalformedSignature, ) from ._compat import normalise_bytes +from .errors import MalformedPointError +from .ellipticcurve import PointJacobi, CurveEdTw __all__ = [ @@ -118,23 +56,49 @@ class BadDigestError(Exception): pass -class MalformedPointError(AssertionError): - """Raised in case the encoding of private or public key is malformed.""" +def _truncate_and_convert_digest(digest, curve, allow_truncate): + """Truncates and converts digest to an integer.""" + if not allow_truncate: + if len(digest) > curve.baselen: + raise BadDigestError( + "this curve ({0}) is too short " + "for the length of your digest ({1})".format( + curve.name, 8 * len(digest) + ) + ) + else: + digest = digest[: curve.baselen] + number = string_to_number(digest) + if allow_truncate: + max_length = bit_length(curve.order) + # we don't use bit_length(number) as that truncates leading zeros + length = len(digest) * 8 + + # See NIST FIPS 186-4: + # + # When the length of the output of the hash function is greater + # than N (i.e., the bit length of q), then the leftmost N bits of + # the hash function output block shall be used in any calculation + # using the hash function output during the generation or + # verification of a digital signature. + # + # as such, we need to shift-out the low-order bits: + number >>= max(0, length - max_length) - pass + return number class VerifyingKey(object): """ Class for handling keys that can verify signatures (public keys). - :ivar ecdsa.curves.Curve curve: The Curve over which all the cryptographic - operations will take place + :ivar `~ecdsa.curves.Curve` ~.curve: The Curve over which all the + cryptographic operations will take place :ivar default_hashfunc: the function that will be used for hashing the data. Should implement the same API as hashlib.sha1 :vartype default_hashfunc: callable :ivar pubkey: the actual public key - :vartype pubkey: ecdsa.ecdsa.Public_key + :vartype pubkey: ~ecdsa.ecdsa.Public_key """ def __init__(self, _error__please_use_generate=None): @@ -149,8 +113,12 @@ class VerifyingKey(object): def __repr__(self): pub_key = self.to_string("compressed") + if self.default_hashfunc: + hash_name = self.default_hashfunc().name + else: + hash_name = "None" return "VerifyingKey.from_string({0!r}, {1!r}, {2})".format( - pub_key, self.curve, self.default_hashfunc().name + pub_key, self.curve, hash_name ) def __eq__(self, other): @@ -159,6 +127,10 @@ class VerifyingKey(object): return self.curve == other.curve and self.pubkey == other.pubkey return NotImplemented + def __ne__(self, other): + """Return False if the points are identical, True otherwise.""" + return not self == other + @classmethod def from_public_point( cls, point, curve=NIST192p, hashfunc=sha1, validate_point=True @@ -169,25 +141,27 @@ class VerifyingKey(object): This is a low-level method, generally you will not want to use it. :param point: The point to wrap around, the actual public key - :type point: ecdsa.ellipticcurve.Point + :type point: ~ecdsa.ellipticcurve.AbstractPoint :param curve: The curve on which the point needs to reside, defaults to NIST192p - :type curve: ecdsa.curves.Curve + :type curve: ~ecdsa.curves.Curve :param hashfunc: The default hash function that will be used for verification, needs to implement the same interface - as hashlib.sha1 + as :py:class:`hashlib.sha1` :type hashfunc: callable - :type bool validate_point: whether to check if the point lies on curve + :type bool validate_point: whether to check if the point lays on curve should always be used if the public point is not a result of our own calculation - :raises MalformedPointError: if the public point does not lie on the + :raises MalformedPointError: if the public point does not lay on the curve :return: Initialised VerifyingKey object :rtype: VerifyingKey """ self = cls(_error__please_use_generate=True) + if isinstance(curve.curve, CurveEdTw): + raise ValueError("Method incompatible with Edwards curves") if not isinstance(point, ellipticcurve.PointJacobi): point = ellipticcurve.PointJacobi.from_affine(point) self.curve = curve @@ -197,7 +171,7 @@ class VerifyingKey(object): curve.generator, point, validate_point ) except ecdsa.InvalidPointError: - raise MalformedPointError("Point does not lie on the curve") + raise MalformedPointError("Point does not lay on the curve") self.pubkey.order = curve.order return self @@ -220,90 +194,45 @@ class VerifyingKey(object): (if set to False) or if it should be delayed to the time of first use (when set to True) """ - self.pubkey.point = ellipticcurve.PointJacobi.from_affine( - self.pubkey.point, True - ) + if isinstance(self.curve.curve, CurveEdTw): + pt = self.pubkey.point + self.pubkey.point = ellipticcurve.PointEdwards( + pt.curve(), + pt.x(), + pt.y(), + 1, + pt.x() * pt.y(), + self.curve.order, + generator=True, + ) + else: + self.pubkey.point = ellipticcurve.PointJacobi.from_affine( + self.pubkey.point, True + ) # as precomputation in now delayed to the time of first use of the # point and we were asked specifically to precompute now, make # sure the precomputation is performed now to preserve the behaviour if not lazy: self.pubkey.point * 2 - @staticmethod - def _from_raw_encoding(string, curve): - """ - Decode public point from :term:`raw encoding`. - - :term:`raw encoding` is the same as the :term:`uncompressed` encoding, - but without the 0x04 byte at the beginning. - """ - order = curve.order - # real assert, from_string() should not call us with different length - assert len(string) == curve.verifying_key_length - xs = string[: curve.baselen] - ys = string[curve.baselen :] - if len(xs) != curve.baselen: - raise MalformedPointError("Unexpected length of encoded x") - if len(ys) != curve.baselen: - raise MalformedPointError("Unexpected length of encoded y") - x = string_to_number(xs) - y = string_to_number(ys) - - return ellipticcurve.PointJacobi(curve.curve, x, y, 1, order) - - @staticmethod - def _from_compressed(string, curve): - """Decode public point from compressed encoding.""" - if string[:1] not in (b("\x02"), b("\x03")): - raise MalformedPointError("Malformed compressed point encoding") - - is_even = string[:1] == b("\x02") - x = string_to_number(string[1:]) - order = curve.order - p = curve.curve.p() - alpha = (pow(x, 3, p) + (curve.curve.a() * x) + curve.curve.b()) % p - try: - beta = square_root_mod_prime(alpha, p) - except SquareRootError as e: - raise MalformedPointError( - "Encoding does not correspond to a point on curve", e - ) - if is_even == bool(beta & 1): - y = p - beta - else: - y = beta - return ellipticcurve.PointJacobi(curve.curve, x, y, 1, order) - - @classmethod - def _from_hybrid(cls, string, curve, validate_point): - """Decode public point from hybrid encoding.""" - # real assert, from_string() should not call us with different types - assert string[:1] in (b("\x06"), b("\x07")) - - # primarily use the uncompressed as it's easiest to handle - point = cls._from_raw_encoding(string[1:], curve) - - # but validate if it's self-consistent if we're asked to do that - if validate_point and ( - point.y() & 1 - and string[:1] != b("\x07") - or (not point.y() & 1) - and string[:1] != b("\x06") - ): - raise MalformedPointError("Inconsistent hybrid point encoding") - - return point - @classmethod def from_string( - cls, string, curve=NIST192p, hashfunc=sha1, validate_point=True + cls, + string, + curve=NIST192p, + hashfunc=sha1, + validate_point=True, + valid_encodings=None, ): """ Initialise the object from byte encoding of public key. The method does accept and automatically detect the type of point encoding used. It supports the :term:`raw encoding`, - :term:`uncompressed`, :term:`compressed` and :term:`hybrid` encodings. + :term:`uncompressed`, :term:`compressed`, and :term:`hybrid` encodings. + It also works with the native encoding of Ed25519 and Ed448 public + keys (technically those are compressed, but encoded differently than + in other signature systems). Note, while the method is named "from_string" it's a misnomer from Python 2 days when there were no binary strings. In Python 3 the @@ -311,46 +240,54 @@ class VerifyingKey(object): :param string: single point encoding of the public key :type string: :term:`bytes-like object` - :param curve: the curve on which the public key is expected to lie - :type curve: ecdsa.curves.Curve + :param curve: the curve on which the public key is expected to lay + :type curve: ~ecdsa.curves.Curve :param hashfunc: The default hash function that will be used for - verification, needs to implement the same interface as hashlib.sha1 + verification, needs to implement the same interface as + hashlib.sha1. Ignored for EdDSA. :type hashfunc: callable - :param validate_point: whether to verify that the point lies on the - provided curve or not, defaults to True + :param validate_point: whether to verify that the point lays on the + provided curve or not, defaults to True. Ignored for EdDSA. :type validate_point: bool - - :raises MalformedPointError: if the public point does not lie on the + :param valid_encodings: list of acceptable point encoding formats, + supported ones are: :term:`uncompressed`, :term:`compressed`, + :term:`hybrid`, and :term:`raw encoding` (specified with ``raw`` + name). All formats by default (specified with ``None``). + Ignored for EdDSA. + :type valid_encodings: :term:`set-like object` + + :raises MalformedPointError: if the public point does not lay on the curve or the encoding is invalid :return: Initialised VerifyingKey object :rtype: VerifyingKey """ - string = normalise_bytes(string) - sig_len = len(string) - if sig_len == curve.verifying_key_length: - point = cls._from_raw_encoding(string, curve) - elif sig_len == curve.verifying_key_length + 1: - if string[:1] in (b("\x06"), b("\x07")): - point = cls._from_hybrid(string, curve, validate_point) - elif string[:1] == b("\x04"): - point = cls._from_raw_encoding(string[1:], curve) - else: - raise MalformedPointError( - "Invalid X9.62 encoding of the public point" - ) - elif sig_len == curve.baselen + 1: - point = cls._from_compressed(string, curve) - else: - raise MalformedPointError( - "Length of string does not match lengths of " - "any of the supported encodings of {0} " - "curve.".format(curve.name) - ) + if isinstance(curve.curve, CurveEdTw): + self = cls(_error__please_use_generate=True) + self.curve = curve + self.default_hashfunc = None # ignored for EdDSA + try: + self.pubkey = eddsa.PublicKey(curve.generator, string) + except ValueError: + raise MalformedPointError("Malformed point for the curve") + return self + + point = PointJacobi.from_bytes( + curve.curve, + string, + validate_encoding=validate_point, + valid_encodings=valid_encodings, + ) return cls.from_public_point(point, curve, hashfunc, validate_point) @classmethod - def from_pem(cls, string, hashfunc=sha1): + def from_pem( + cls, + string, + hashfunc=sha1, + valid_encodings=None, + valid_curve_encodings=None, + ): """ Initialise from public key stored in :term:`PEM` format. @@ -359,19 +296,40 @@ class VerifyingKey(object): See the :func:`~VerifyingKey.from_der()` method for details of the format supported. - Note: only a single PEM object encoding is supported in provided + Note: only a single PEM object decoding is supported in provided string. :param string: text with PEM-encoded public ECDSA key :type string: str + :param valid_encodings: list of allowed point encodings. + By default :term:`uncompressed`, :term:`compressed`, and + :term:`hybrid`. To read malformed files, include + :term:`raw encoding` with ``raw`` in the list. + :type valid_encodings: :term:`set-like object` + :param valid_curve_encodings: list of allowed encoding formats + for curve parameters. By default (``None``) all are supported: + ``named_curve`` and ``explicit``. + :type valid_curve_encodings: :term:`set-like object` + :return: Initialised VerifyingKey object :rtype: VerifyingKey """ - return cls.from_der(der.unpem(string), hashfunc=hashfunc) + return cls.from_der( + der.unpem(string), + hashfunc=hashfunc, + valid_encodings=valid_encodings, + valid_curve_encodings=valid_curve_encodings, + ) @classmethod - def from_der(cls, string, hashfunc=sha1): + def from_der( + cls, + string, + hashfunc=sha1, + valid_encodings=None, + valid_curve_encodings=None, + ): """ Initialise the key stored in :term:`DER` format. @@ -396,10 +354,21 @@ class VerifyingKey(object): :param string: binary string with the DER encoding of public ECDSA key :type string: bytes-like object + :param valid_encodings: list of allowed point encodings. + By default :term:`uncompressed`, :term:`compressed`, and + :term:`hybrid`. To read malformed files, include + :term:`raw encoding` with ``raw`` in the list. + :type valid_encodings: :term:`set-like object` + :param valid_curve_encodings: list of allowed encoding formats + for curve parameters. By default (``None``) all are supported: + ``named_curve`` and ``explicit``. + :type valid_curve_encodings: :term:`set-like object` :return: Initialised VerifyingKey object :rtype: VerifyingKey """ + if valid_encodings is None: + valid_encodings = set(["uncompressed", "compressed", "hybrid"]) string = normalise_bytes(string) # [[oid_ecPublicKey,oid_curve], point_str_bitstring] s1, empty = der.remove_sequence(string) @@ -410,18 +379,22 @@ class VerifyingKey(object): s2, point_str_bitstring = der.remove_sequence(s1) # s2 = oid_ecPublicKey,oid_curve oid_pk, rest = der.remove_object(s2) - oid_curve, empty = der.remove_object(rest) - if empty != b"": - raise der.UnexpectedDER( - "trailing junk after DER pubkey objects: %s" - % binascii.hexlify(empty) - ) + if oid_pk in (Ed25519.oid, Ed448.oid): + if oid_pk == Ed25519.oid: + curve = Ed25519 + else: + assert oid_pk == Ed448.oid + curve = Ed448 + point_str, empty = der.remove_bitstring(point_str_bitstring, 0) + if empty: + raise der.UnexpectedDER("trailing junk after public key") + return cls.from_string(point_str, curve, None) if not oid_pk == oid_ecPublicKey: raise der.UnexpectedDER( "Unexpected object identifier in DER " "encoding: {0!r}".format(oid_pk) ) - curve = find_curve(oid_curve) + curve = Curve.from_der(rest, valid_curve_encodings) point_str, empty = der.remove_bitstring(point_str_bitstring, 0) if empty != b"": raise der.UnexpectedDER( @@ -431,11 +404,22 @@ class VerifyingKey(object): # raw encoding of point is invalid in DER files if len(point_str) == curve.verifying_key_length: raise der.UnexpectedDER("Malformed encoding of public point") - return cls.from_string(point_str, curve, hashfunc=hashfunc) + return cls.from_string( + point_str, + curve, + hashfunc=hashfunc, + valid_encodings=valid_encodings, + ) @classmethod def from_public_key_recovery( - cls, signature, data, curve, hashfunc=sha1, sigdecode=sigdecode_string + cls, + signature, + data, + curve, + hashfunc=sha1, + sigdecode=sigdecode_string, + allow_truncate=True, ): """ Return keys that can be used as verifiers of the provided signature. @@ -448,7 +432,7 @@ class VerifyingKey(object): :param data: the data to be hashed for signature verification :type data: bytes-like object :param curve: the curve over which the signature was performed - :type curve: ecdsa.curves.Curve + :type curve: ~ecdsa.curves.Curve :param hashfunc: The default hash function that will be used for verification, needs to implement the same interface as hashlib.sha1 :type hashfunc: callable @@ -458,15 +442,25 @@ class VerifyingKey(object): a tuple with two integers, "r" as the first one and "s" as the second one. See :func:`ecdsa.util.sigdecode_string` and :func:`ecdsa.util.sigdecode_der` for examples. + :param bool allow_truncate: if True, the provided hashfunc can generate + values larger than the bit size of the order of the curve, the + extra bits (at the end of the digest) will be truncated. :type sigdecode: callable :return: Initialised VerifyingKey objects :rtype: list of VerifyingKey """ + if isinstance(curve.curve, CurveEdTw): + raise ValueError("Method unsupported for Edwards curves") data = normalise_bytes(data) digest = hashfunc(data).digest() return cls.from_public_key_recovery_with_digest( - signature, digest, curve, hashfunc=hashfunc, sigdecode=sigdecode + signature, + digest, + curve, + hashfunc=hashfunc, + sigdecode=sigdecode, + allow_truncate=allow_truncate, ) @classmethod @@ -477,6 +471,7 @@ class VerifyingKey(object): curve, hashfunc=sha1, sigdecode=sigdecode_string, + allow_truncate=False, ): """ Return keys that can be used as verifiers of the provided signature. @@ -489,7 +484,7 @@ class VerifyingKey(object): :param digest: the hash value of the message signed by the signature :type digest: bytes-like object :param curve: the curve over which the signature was performed - :type curve: ecdsa.curves.Curve + :type curve: ~ecdsa.curves.Curve :param hashfunc: The default hash function that will be used for verification, needs to implement the same interface as hashlib.sha1 :type hashfunc: callable @@ -500,17 +495,24 @@ class VerifyingKey(object): second one. See :func:`ecdsa.util.sigdecode_string` and :func:`ecdsa.util.sigdecode_der` for examples. :type sigdecode: callable - + :param bool allow_truncate: if True, the provided hashfunc can generate + values larger than the bit size of the order of the curve (and + the length of provided `digest`), the extra bits (at the end of the + digest) will be truncated. :return: Initialised VerifyingKey object :rtype: VerifyingKey """ + if isinstance(curve.curve, CurveEdTw): + raise ValueError("Method unsupported for Edwards curves") generator = curve.generator r, s = sigdecode(signature, generator.order()) sig = ecdsa.Signature(r, s) digest = normalise_bytes(digest) - digest_as_number = string_to_number(digest) + digest_as_number = _truncate_and_convert_digest( + digest, curve, allow_truncate + ) pks = sig.recover_public_keys(digest_as_number, generator) # Transforms the ecdsa.Public_key object into a VerifyingKey @@ -519,30 +521,6 @@ class VerifyingKey(object): ] return verifying_keys - def _raw_encode(self): - """Convert the public key to the :term:`raw encoding`.""" - order = self.pubkey.order - x_str = number_to_string(self.pubkey.point.x(), order) - y_str = number_to_string(self.pubkey.point.y(), order) - return x_str + y_str - - def _compressed_encode(self): - """Encode the public point into the compressed form.""" - order = self.pubkey.order - x_str = number_to_string(self.pubkey.point.x(), order) - if self.pubkey.point.y() & 1: - return b("\x03") + x_str - else: - return b("\x02") + x_str - - def _hybrid_encode(self): - """Encode the public point into the hybrid form.""" - raw_enc = self._raw_encode() - if self.pubkey.point.y() & 1: - return b("\x07") + raw_enc - else: - return b("\x06") + raw_enc - def to_string(self, encoding="raw"): """ Convert the public key to a byte string. @@ -564,16 +542,11 @@ class VerifyingKey(object): :rtype: bytes """ assert encoding in ("raw", "uncompressed", "compressed", "hybrid") - if encoding == "raw": - return self._raw_encode() - elif encoding == "uncompressed": - return b("\x04") + self._raw_encode() - elif encoding == "hybrid": - return self._hybrid_encode() - else: - return self._compressed_encode() + return self.pubkey.point.to_bytes(encoding) - def to_pem(self, point_encoding="uncompressed"): + def to_pem( + self, point_encoding="uncompressed", curve_parameters_encoding=None + ): """ Convert the public key to the :term:`PEM` format. @@ -587,6 +560,9 @@ class VerifyingKey(object): of public keys. "uncompressed" is most portable, "compressed" is smallest. "hybrid" is uncommon and unsupported by most implementations, it is as big as "uncompressed". + :param str curve_parameters_encoding: the encoding for curve parameters + to use, by default tries to use ``named_curve`` encoding, + if that is not possible, falls back to ``explicit`` encoding. :return: portable encoding of the public key :rtype: bytes @@ -594,9 +570,14 @@ class VerifyingKey(object): .. warning:: The PEM is encoded to US-ASCII, it needs to be re-encoded if the system is incompatible (e.g. uses UTF-16) """ - return der.topem(self.to_der(point_encoding), "PUBLIC KEY") + return der.topem( + self.to_der(point_encoding, curve_parameters_encoding), + "PUBLIC KEY", + ) - def to_der(self, point_encoding="uncompressed"): + def to_der( + self, point_encoding="uncompressed", curve_parameters_encoding=None + ): """ Convert the public key to the :term:`DER` format. @@ -608,6 +589,9 @@ class VerifyingKey(object): of public keys. "uncompressed" is most portable, "compressed" is smallest. "hybrid" is uncommon and unsupported by most implementations, it is as big as "uncompressed". + :param str curve_parameters_encoding: the encoding for curve parameters + to use, by default tries to use ``named_curve`` encoding, + if that is not possible, falls back to ``explicit`` encoding. :return: DER encoding of the public key :rtype: bytes @@ -615,9 +599,15 @@ class VerifyingKey(object): if point_encoding == "raw": raise ValueError("raw point_encoding not allowed in DER") point_str = self.to_string(point_encoding) + if isinstance(self.curve.curve, CurveEdTw): + return der.encode_sequence( + der.encode_sequence(der.encode_oid(*self.curve.oid)), + der.encode_bitstring(bytes(point_str), 0), + ) return der.encode_sequence( der.encode_sequence( - encoded_oid_ecPublicKey, self.curve.encoded_oid + encoded_oid_ecPublicKey, + self.curve.to_der(curve_parameters_encoding, point_encoding), ), # 0 is the number of unused bits in the # bit string @@ -643,10 +633,10 @@ class VerifyingKey(object): as the `sigdecode` parameter. :param signature: encoding of the signature - :type signature: sigdecode method dependant + :type signature: sigdecode method dependent :param data: data signed by the `signature`, will be hashed using `hashfunc`, if specified, or default hash function - :type data: bytes like object + :type data: :term:`bytes-like object` :param hashfunc: The default hash function that will be used for verification, needs to implement the same interface as hashlib.sha1 :type hashfunc: callable @@ -671,6 +661,12 @@ class VerifyingKey(object): # signature doesn't have to be a bytes-like-object so don't normalise # it, the decoders will do that data = normalise_bytes(data) + if isinstance(self.curve.curve, CurveEdTw): + signature = normalise_bytes(signature) + try: + return self.pubkey.verify(data, signature) + except (ValueError, MalformedPointError) as e: + raise BadSignatureError("Signature verification failed", e) hashfunc = hashfunc or self.default_hashfunc digest = hashfunc(data).digest() @@ -692,9 +688,9 @@ class VerifyingKey(object): as the `sigdecode` parameter. :param signature: encoding of the signature - :type signature: sigdecode method dependant + :type signature: sigdecode method dependent :param digest: raw hash value that the signature authenticates. - :type digest: bytes like object + :type digest: :term:`bytes-like object` :param sigdecode: Callable to define the way the signature needs to be decoded to an object, needs to handle `signature` as the first parameter, the curve order (an int) as the second and return @@ -717,27 +713,11 @@ class VerifyingKey(object): # signature doesn't have to be a bytes-like-object so don't normalise # it, the decoders will do that digest = normalise_bytes(digest) - if not allow_truncate and len(digest) > self.curve.baselen: - raise BadDigestError( - "this curve (%s) is too short " - "for your digest (%d)" % (self.curve.name, 8 * len(digest)) - ) - number = string_to_number(digest) - if allow_truncate: - max_length = bit_length(self.curve.order) - # we don't use bit_length(number) as that truncates leading zeros - length = len(digest) * 8 - - # See NIST FIPS 186-4: - # - # When the length of the output of the hash function is greater - # than N (i.e., the bit length of q), then the leftmost N bits of - # the hash function output block shall be used in any calculation - # using the hash function output during the generation or - # verification of a digital signature. - # - # as such, we need to shift-out the low-order bits: - number >>= max(0, length - max_length) + number = _truncate_and_convert_digest( + digest, + self.curve, + allow_truncate, + ) try: r, s = sigdecode(signature, self.pubkey.order) @@ -753,14 +733,14 @@ class SigningKey(object): """ Class for handling keys that can create signatures (private keys). - :ivar ecdsa.curves.Curve curve: The Curve over which all the cryptographic - operations will take place + :ivar `~ecdsa.curves.Curve` curve: The Curve over which all the + cryptographic operations will take place :ivar default_hashfunc: the function that will be used for hashing the - data. Should implement the same API as hashlib.sha1 + data. Should implement the same API as :py:class:`hashlib.sha1` :ivar int baselen: the length of a :term:`raw encoding` of private key - :ivar ecdsa.keys.VerifyingKey verifying_key: the public key + :ivar `~ecdsa.keys.VerifyingKey` verifying_key: the public key associated with this private key - :ivar ecdsa.ecdsa.Private_key privkey: the actual private key + :ivar `~ecdsa.ecdsa.Private_key` privkey: the actual private key """ def __init__(self, _error__please_use_generate=None): @@ -783,6 +763,37 @@ class SigningKey(object): ) return NotImplemented + def __ne__(self, other): + """Return False if the points are identical, True otherwise.""" + return not self == other + + @classmethod + def _twisted_edwards_keygen(cls, curve, entropy): + """Generate a private key on a Twisted Edwards curve.""" + if not entropy: + entropy = os.urandom + random = entropy(curve.baselen) + private_key = eddsa.PrivateKey(curve.generator, random) + public_key = private_key.public_key() + + verifying_key = VerifyingKey.from_string( + public_key.public_key(), curve + ) + + self = cls(_error__please_use_generate=True) + self.curve = curve + self.default_hashfunc = None + self.baselen = curve.baselen + self.privkey = private_key + self.verifying_key = verifying_key + return self + + @classmethod + def _weierstrass_keygen(cls, curve, entropy, hashfunc): + """Generate a private key on a Weierstrass curve.""" + secexp = randrange(curve.order, entropy) + return cls.from_secret_exponent(secexp, curve, hashfunc) + @classmethod def generate(cls, curve=NIST192p, entropy=None, hashfunc=sha1): """ @@ -790,7 +801,7 @@ class SigningKey(object): :param curve: The curve on which the point needs to reside, defaults to NIST192p - :type curve: ecdsa.curves.Curve + :type curve: ~ecdsa.curves.Curve :param entropy: Source of randomness for generating the private keys, should provide cryptographically secure random numbers if the keys need to be secure. Uses os.urandom() by default. @@ -803,8 +814,9 @@ class SigningKey(object): :return: Initialised SigningKey object :rtype: SigningKey """ - secexp = randrange(curve.order, entropy) - return cls.from_secret_exponent(secexp, curve, hashfunc) + if isinstance(curve.curve, CurveEdTw): + return cls._twisted_edwards_keygen(curve, entropy) + return cls._weierstrass_keygen(curve, entropy, hashfunc) @classmethod def from_secret_exponent(cls, secexp, curve=NIST192p, hashfunc=sha1): @@ -817,7 +829,7 @@ class SigningKey(object): :param int secexp: secret multiplier (the actual private key in ECDSA). Needs to be an integer between 1 and the curve order. :param curve: The curve on which the point needs to reside - :type curve: ecdsa.curves.Curve + :type curve: ~ecdsa.curves.Curve :param hashfunc: The default hash function that will be used for signing, needs to implement the same interface as hashlib.sha1 @@ -831,6 +843,11 @@ class SigningKey(object): :return: Initialised SigningKey object :rtype: SigningKey """ + if isinstance(curve.curve, CurveEdTw): + raise ValueError( + "Edwards keys don't support setting the secret scalar " + "(exponent) directly" + ) self = cls(_error__please_use_generate=True) self.curve = curve self.default_hashfunc = hashfunc @@ -862,9 +879,9 @@ class SigningKey(object): In Python 3, the expected type is `bytes`. :param string: the raw encoding of the private key - :type string: bytes like object + :type string: :term:`bytes-like object` :param curve: The curve on which the point needs to reside - :type curve: ecdsa.curves.Curve + :type curve: ~ecdsa.curves.Curve :param hashfunc: The default hash function that will be used for signing, needs to implement the same interface as hashlib.sha1 @@ -879,16 +896,27 @@ class SigningKey(object): :rtype: SigningKey """ string = normalise_bytes(string) + if len(string) != curve.baselen: raise MalformedPointError( "Invalid length of private key, received {0}, " "expected {1}".format(len(string), curve.baselen) ) + if isinstance(curve.curve, CurveEdTw): + self = cls(_error__please_use_generate=True) + self.curve = curve + self.default_hashfunc = None # Ignored for EdDSA + self.baselen = curve.baselen + self.privkey = eddsa.PrivateKey(curve.generator, string) + self.verifying_key = VerifyingKey.from_string( + self.privkey.public_key().public_key(), curve + ) + return self secexp = string_to_number(string) return cls.from_secret_exponent(secexp, curve, hashfunc) @classmethod - def from_pem(cls, string, hashfunc=sha1): + def from_pem(cls, string, hashfunc=sha1, valid_curve_encodings=None): """ Initialise from key stored in :term:`PEM` format. @@ -908,6 +936,11 @@ class SigningKey(object): :param string: text with PEM-encoded private ECDSA key :type string: str + :param valid_curve_encodings: list of allowed encoding formats + for curve parameters. By default (``None``) all are supported: + ``named_curve`` and ``explicit``. + :type valid_curve_encodings: :term:`set-like object` + :raises MalformedPointError: if the length of encoding doesn't match the provided curve or the encoded values is too large @@ -918,7 +951,7 @@ class SigningKey(object): :return: Initialised SigningKey object :rtype: SigningKey """ - if not PY2 and isinstance(string, str): + if not PY2 and isinstance(string, str): # pragma: no branch string = string.encode() # The privkey pem may have multiple sections, commonly it also has @@ -928,10 +961,14 @@ class SigningKey(object): if private_key_index == -1: private_key_index = string.index(b"-----BEGIN PRIVATE KEY-----") - return cls.from_der(der.unpem(string[private_key_index:]), hashfunc) + return cls.from_der( + der.unpem(string[private_key_index:]), + hashfunc, + valid_curve_encodings, + ) @classmethod - def from_der(cls, string, hashfunc=sha1): + def from_der(cls, string, hashfunc=sha1, valid_curve_encodings=None): """ Initialise from key stored in :term:`DER` format. @@ -952,14 +989,14 @@ class SigningKey(object): `publicKey` field is ignored completely (errors, if any, in it will be undetected). - The only format supported for the `parameters` field is the named - curve method. Explicit encoding of curve parameters is not supported. + Two formats are supported for the `parameters` field: the named + curve and the explicit encoding of curve parameters. In the legacy ssleay format, this implementation requires the optional `parameters` field to get the curve name. In PKCS #8 format, the curve is part of the PrivateKeyAlgorithmIdentifier. The PKCS #8 format includes an ECPrivateKey object as the `privateKey` - field within a larger structure: + field within a larger structure:: OneAsymmetricKey ::= SEQUENCE { version Version, @@ -975,7 +1012,12 @@ class SigningKey(object): in them will not be detected. :param string: binary string with DER-encoded private ECDSA key - :type string: bytes like object + :type string: :term:`bytes-like object` + :param valid_curve_encodings: list of allowed encoding formats + for curve parameters. By default (``None``) all are supported: + ``named_curve`` and ``explicit``. + Ignored for EdDSA. + :type valid_curve_encodings: :term:`set-like object` :raises MalformedPointError: if the length of encoding doesn't match the provided curve or the encoded values is too large @@ -1010,13 +1052,44 @@ class SigningKey(object): sequence, s = der.remove_sequence(s) algorithm_oid, algorithm_identifier = der.remove_object(sequence) - curve_oid, empty = der.remove_object(algorithm_identifier) - curve = find_curve(curve_oid) + + if algorithm_oid in (Ed25519.oid, Ed448.oid): + if algorithm_identifier: + raise der.UnexpectedDER( + "Non NULL parameters for a EdDSA key" + ) + key_str_der, s = der.remove_octet_string(s) + + # As RFC5958 describe, there are may be optional Attributes + # and Publickey. Don't raise error if something after + # Privatekey + + # TODO parse attributes or validate publickey + # if s: + # raise der.UnexpectedDER( + # "trailing junk inside the privateKey" + # ) + key_str, s = der.remove_octet_string(key_str_der) + if s: + raise der.UnexpectedDER( + "trailing junk after the encoded private key" + ) + + if algorithm_oid == Ed25519.oid: + curve = Ed25519 + else: + assert algorithm_oid == Ed448.oid + curve = Ed448 + + return cls.from_string(key_str, curve, None) if algorithm_oid not in (oid_ecPublicKey, oid_ecDH, oid_ecMQV): raise der.UnexpectedDER( "unexpected algorithm identifier '%s'" % (algorithm_oid,) ) + + curve = Curve.from_der(algorithm_identifier, valid_curve_encodings) + if empty != b"": raise der.UnexpectedDER( "unexpected data after algorithm identifier: %s" @@ -1053,13 +1126,7 @@ class SigningKey(object): raise der.UnexpectedDER( "expected tag 0 in DER privkey, got %d" % tag ) - curve_oid, empty = der.remove_object(curve_oid_str) - if empty != b(""): - raise der.UnexpectedDER( - "trailing junk after DER privkey " - "curve_oid: %s" % binascii.hexlify(empty) - ) - curve = find_curve(curve_oid) + curve = Curve.from_der(curve_oid_str, valid_curve_encodings) # we don't actually care about the following fields # @@ -1091,11 +1158,18 @@ class SigningKey(object): :return: raw encoding of private key :rtype: bytes """ + if isinstance(self.curve.curve, CurveEdTw): + return bytes(self.privkey.private_key) secexp = self.privkey.secret_multiplier s = number_to_string(secexp, self.privkey.order) return s - def to_pem(self, point_encoding="uncompressed", format="ssleay"): + def to_pem( + self, + point_encoding="uncompressed", + format="ssleay", + curve_parameters_encoding=None, + ): """ Convert the private key to the :term:`PEM` format. @@ -1109,6 +1183,11 @@ class SigningKey(object): :param str point_encoding: format to use for encoding public point :param str format: either ``ssleay`` (default) or ``pkcs8`` + :param str curve_parameters_encoding: format of encoded curve + parameters, default depends on the curve, if the curve has + an associated OID, ``named_curve`` format will be used, + if no OID is associated with the curve, the fallback of + ``explicit`` parameters will be used. :return: PEM encoded private key :rtype: bytes @@ -1119,9 +1198,26 @@ class SigningKey(object): # TODO: "BEGIN ECPARAMETERS" assert format in ("ssleay", "pkcs8") header = "EC PRIVATE KEY" if format == "ssleay" else "PRIVATE KEY" - return der.topem(self.to_der(point_encoding, format), header) + return der.topem( + self.to_der(point_encoding, format, curve_parameters_encoding), + header, + ) + + def _encode_eddsa(self): + """Create a PKCS#8 encoding of EdDSA keys.""" + ec_private_key = der.encode_octet_string(self.to_string()) + return der.encode_sequence( + der.encode_integer(0), + der.encode_sequence(der.encode_oid(*self.curve.oid)), + der.encode_octet_string(ec_private_key), + ) - def to_der(self, point_encoding="uncompressed", format="ssleay"): + def to_der( + self, + point_encoding="uncompressed", + format="ssleay", + curve_parameters_encoding=None, + ): """ Convert the private key to the :term:`DER` format. @@ -1131,7 +1227,15 @@ class SigningKey(object): The public key will be included in the generated string. :param str point_encoding: format to use for encoding public point - :param str format: either ``ssleay`` (default) or ``pkcs8`` + Ignored for EdDSA + :param str format: either ``ssleay`` (default) or ``pkcs8``. + EdDSA keys require ``pkcs8``. + :param str curve_parameters_encoding: format of encoded curve + parameters, default depends on the curve, if the curve has + an associated OID, ``named_curve`` format will be used, + if no OID is associated with the curve, the fallback of + ``explicit`` parameters will be used. + Ignored for EdDSA. :return: DER encoded private key :rtype: bytes @@ -1141,15 +1245,27 @@ class SigningKey(object): if point_encoding == "raw": raise ValueError("raw encoding not allowed in DER") assert format in ("ssleay", "pkcs8") + if isinstance(self.curve.curve, CurveEdTw): + if format != "pkcs8": + raise ValueError("Only PKCS#8 format supported for EdDSA keys") + return self._encode_eddsa() encoded_vk = self.get_verifying_key().to_string(point_encoding) - # the 0 in encode_bitstring specifies the number of unused bits - # in the `encoded_vk` string - ec_private_key = der.encode_sequence( + priv_key_elems = [ der.encode_integer(1), der.encode_octet_string(self.to_string()), - der.encode_constructed(0, self.curve.encoded_oid), - der.encode_constructed(1, der.encode_bitstring(encoded_vk, 0)), + ] + if format == "ssleay": + priv_key_elems.append( + der.encode_constructed( + 0, self.curve.to_der(curve_parameters_encoding) + ) + ) + # the 0 in encode_bitstring specifies the number of unused bits + # in the `encoded_vk` string + priv_key_elems.append( + der.encode_constructed(1, der.encode_bitstring(encoded_vk, 0)) ) + ec_private_key = der.encode_sequence(*priv_key_elems) if format == "ssleay": return ec_private_key @@ -1159,7 +1275,8 @@ class SigningKey(object): # top-level structure. der.encode_integer(1), der.encode_sequence( - der.encode_oid(*oid_ecPublicKey), self.curve.encoded_oid + der.encode_oid(*oid_ecPublicKey), + self.curve.to_der(curve_parameters_encoding), ), der.encode_octet_string(ec_private_key), ) @@ -1184,20 +1301,27 @@ class SigningKey(object): extra_entropy=b"", ): """ - Create signature over data using the deterministic RFC6679 algorithm. + Create signature over data. - The data will be hashed using the `hashfunc` function before signing. + For Weierstrass curves it uses the deterministic RFC6979 algorithm. + For Edwards curves it uses the standard EdDSA algorithm. + + For ECDSA the data will be hashed using the `hashfunc` function before + signing. + For EdDSA the data will be hashed with the hash associated with the + curve (SHA-512 for Ed25519 and SHAKE-256 for Ed448). This is the recommended method for performing signatures when hashing of data is necessary. :param data: data to be hashed and computed signature over - :type data: bytes like object + :type data: :term:`bytes-like object` :param hashfunc: hash function to use for computing the signature, if unspecified, the default hash function selected during object initialisation will be used (see `VerifyingKey.default_hashfunc`). The object needs to implement the same interface as hashlib.sha1. + Ignored with EdDSA. :type hashfunc: callable :param sigencode: function used to encode the signature. The function needs to accept three parameters: the two integers @@ -1205,16 +1329,22 @@ class SigningKey(object): signature was computed. It needs to return an encoded signature. See `ecdsa.util.sigencode_string` and `ecdsa.util.sigencode_der` as examples of such functions. + Ignored with EdDSA. :type sigencode: callable :param extra_entropy: additional data that will be fed into the random number generator used in the RFC6979 process. Entirely optional. - :type extra_entropy: bytes like object + Ignored with EdDSA. + :type extra_entropy: :term:`bytes-like object` :return: encoded signature over `data` - :rtype: bytes or sigencode function dependant type + :rtype: bytes or sigencode function dependent type """ hashfunc = hashfunc or self.default_hashfunc data = normalise_bytes(data) + + if isinstance(self.curve.curve, CurveEdTw): + return self.privkey.sign(data) + extra_entropy = normalise_bytes(extra_entropy) digest = hashfunc(data).digest() @@ -1235,7 +1365,7 @@ class SigningKey(object): allow_truncate=False, ): """ - Create signature for digest using the deterministic RFC6679 algorithm. + Create signature for digest using the deterministic RFC6979 algorithm. `digest` should be the output of cryptographically secure hash function like SHA256 or SHA-3-256. @@ -1244,32 +1374,36 @@ class SigningKey(object): hashing of data is necessary. :param digest: hash of data that will be signed - :type digest: bytes like object + :type digest: :term:`bytes-like object` :param hashfunc: hash function to use for computing the random "k" value from RFC6979 process, if unspecified, the default hash function selected during object initialisation will be used (see - `VerifyingKey.default_hashfunc`). The object needs to implement - the same interface as hashlib.sha1. + :attr:`.VerifyingKey.default_hashfunc`). The object needs to + implement + the same interface as :func:`~hashlib.sha1` from :py:mod:`hashlib`. :type hashfunc: callable :param sigencode: function used to encode the signature. The function needs to accept three parameters: the two integers that are the signature and the order of the curve over which the signature was computed. It needs to return an encoded signature. - See `ecdsa.util.sigencode_string` and `ecdsa.util.sigencode_der` + See :func:`~ecdsa.util.sigencode_string` and + :func:`~ecdsa.util.sigencode_der` as examples of such functions. :type sigencode: callable :param extra_entropy: additional data that will be fed into the random number generator used in the RFC6979 process. Entirely optional. - :type extra_entropy: bytes like object + :type extra_entropy: :term:`bytes-like object` :param bool allow_truncate: if True, the provided digest can have bigger bit-size than the order of the curve, the extra bits (at the end of the digest) will be truncated. Use it when signing SHA-384 output using NIST256p or in similar situations. :return: encoded signature for the `digest` hash - :rtype: bytes or sigencode function dependant type + :rtype: bytes or sigencode function dependent type """ + if isinstance(self.curve.curve, CurveEdTw): + raise ValueError("Method unsupported for Edwards curves") secexp = self.privkey.secret_multiplier hashfunc = hashfunc or self.default_hashfunc digest = normalise_bytes(digest) @@ -1311,7 +1445,11 @@ class SigningKey(object): allow_truncate=True, ): """ - Create signature over data using the probabilistic ECDSA algorithm. + Create signature over data. + + Uses the probabilistic ECDSA algorithm for Weierstrass curves + (NIST256p, etc.) and the deterministic EdDSA algorithm for the + Edwards curves (Ed25519, Ed448). This method uses the standard ECDSA algorithm that requires a cryptographically secure random number generator. @@ -1320,46 +1458,62 @@ class SigningKey(object): method instead of this one. :param data: data that will be hashed for signing - :type data: bytes like object - :param callable entropy: randomness source, os.urandom by default - :param hashfunc: hash function to use for hashing the provided `data`. + :type data: :term:`bytes-like object` + :param callable entropy: randomness source, :func:`os.urandom` by + default. Ignored with EdDSA. + :param hashfunc: hash function to use for hashing the provided + ``data``. If unspecified the default hash function selected during object initialisation will be used (see - `VerifyingKey.default_hashfunc`). - Should behave like hashlib.sha1. The output length of the + :attr:`.VerifyingKey.default_hashfunc`). + Should behave like :func:`~hashlib.sha1` from :py:mod:`hashlib`. + The output length of the hash (in bytes) must not be longer than the length of the curve order (rounded up to the nearest byte), so using SHA256 with NIST256p is ok, but SHA256 with NIST192p is not. (In the 2**-96ish unlikely event of a hash output larger than the curve order, the hash will effectively be wrapped mod n). - Use hashfunc=hashlib.sha1 to match openssl's -ecdsa-with-SHA1 mode, - or hashfunc=hashlib.sha256 for openssl-1.0.0's -ecdsa-with-SHA256. + If you want to explicitly allow use of large hashes with small + curves set the ``allow_truncate`` to ``True``. + Use ``hashfunc=hashlib.sha1`` to match openssl's + ``-ecdsa-with-SHA1`` mode, + or ``hashfunc=hashlib.sha256`` for openssl-1.0.0's + ``-ecdsa-with-SHA256``. + Ignored for EdDSA :type hashfunc: callable :param sigencode: function used to encode the signature. The function needs to accept three parameters: the two integers that are the signature and the order of the curve over which the signature was computed. It needs to return an encoded signature. - See `ecdsa.util.sigencode_string` and `ecdsa.util.sigencode_der` + See :func:`~ecdsa.util.sigencode_string` and + :func:`~ecdsa.util.sigencode_der` as examples of such functions. + Ignored for EdDSA :type sigencode: callable :param int k: a pre-selected nonce for calculating the signature. In typical use cases, it should be set to None (the default) to allow its generation from an entropy source. - :param bool allow_truncate: if True, the provided digest can have + Ignored for EdDSA. + :param bool allow_truncate: if ``True``, the provided digest can have bigger bit-size than the order of the curve, the extra bits (at the end of the digest) will be truncated. Use it when signing SHA-384 output using NIST256p or in similar situations. True by default. + Ignored for EdDSA. - :raises RSZeroError: in the unlikely event when "r" parameter or - "s" parameter is equal 0 as that would leak the key. Calee should - try a better entropy source or different 'k' in such case. + :raises RSZeroError: in the unlikely event when *r* parameter or + *s* parameter of the created signature is equal 0, as that would + leak the key. Caller should try a better entropy source, retry with + different ``k``, or use the + :func:`~SigningKey.sign_deterministic` in such case. :return: encoded signature of the hash of `data` - :rtype: bytes or sigencode function dependant type + :rtype: bytes or sigencode function dependent type """ hashfunc = hashfunc or self.default_hashfunc data = normalise_bytes(data) + if isinstance(self.curve.curve, CurveEdTw): + return self.sign_deterministic(data) h = hashfunc(data).digest() return self.sign_digest(h, entropy, sigencode, k, allow_truncate) @@ -1384,7 +1538,7 @@ class SigningKey(object): instead of this one. :param digest: hash value that will be signed - :type digest: bytes like object + :type digest: :term:`bytes-like object` :param callable entropy: randomness source, os.urandom by default :param sigencode: function used to encode the signature. The function needs to accept three parameters: the two integers @@ -1402,21 +1556,22 @@ class SigningKey(object): SHA-384 output using NIST256p or in similar situations. :raises RSZeroError: in the unlikely event when "r" parameter or - "s" parameter is equal 0 as that would leak the key. Calee should - try a better entropy source in such case. + "s" parameter of the created signature is equal 0, as that would + leak the key. Caller should try a better entropy source, retry with + different 'k', or use the + :func:`~SigningKey.sign_digest_deterministic` in such case. :return: encoded signature for the `digest` hash - :rtype: bytes or sigencode function dependant type + :rtype: bytes or sigencode function dependent type """ + if isinstance(self.curve.curve, CurveEdTw): + raise ValueError("Method unsupported for Edwards curves") digest = normalise_bytes(digest) - if allow_truncate: - digest = digest[: self.curve.baselen] - if len(digest) > self.curve.baselen: - raise BadDigestError( - "this curve (%s) is too short " - "for your digest (%d)" % (self.curve.name, 8 * len(digest)) - ) - number = string_to_number(digest) + number = _truncate_and_convert_digest( + digest, + self.curve, + allow_truncate, + ) r, s = self.sign_number(number, entropy, k) return sigencode(r, s, self.privkey.order) @@ -1435,12 +1590,16 @@ class SigningKey(object): it will be selected at random using the entropy source. :raises RSZeroError: in the unlikely event when "r" parameter or - "s" parameter is equal 0 as that would leak the key. Calee should - try a different 'k' in such case. + "s" parameter of the created signature is equal 0, as that would + leak the key. Caller should try a better entropy source, retry with + different 'k', or use the + :func:`~SigningKey.sign_digest_deterministic` in such case. :return: the "r" and "s" parameters of the signature :rtype: tuple of ints """ + if isinstance(self.curve.curve, CurveEdTw): + raise ValueError("Method unsupported for Edwards curves") order = self.privkey.order if k is not None: |