285 lines
9.4 KiB
Python
285 lines
9.4 KiB
Python
# Copyright 2013 Donald Stufft and individual contributors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import absolute_import, division, print_function
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from nacl import exceptions as exc
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from nacl._sodium import ffi, lib
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from nacl.exceptions import ensure
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crypto_sign_BYTES = lib.crypto_sign_bytes()
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# crypto_sign_SEEDBYTES = lib.crypto_sign_seedbytes()
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crypto_sign_SEEDBYTES = lib.crypto_sign_secretkeybytes() // 2
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crypto_sign_PUBLICKEYBYTES = lib.crypto_sign_publickeybytes()
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crypto_sign_SECRETKEYBYTES = lib.crypto_sign_secretkeybytes()
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crypto_sign_curve25519_BYTES = lib.crypto_box_secretkeybytes()
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crypto_sign_ed25519ph_STATEBYTES = lib.crypto_sign_ed25519ph_statebytes()
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def crypto_sign_keypair():
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"""
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Returns a randomly generated public key and secret key.
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:rtype: (bytes(public_key), bytes(secret_key))
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"""
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pk = ffi.new("unsigned char[]", crypto_sign_PUBLICKEYBYTES)
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sk = ffi.new("unsigned char[]", crypto_sign_SECRETKEYBYTES)
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rc = lib.crypto_sign_keypair(pk, sk)
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ensure(rc == 0,
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'Unexpected library error',
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raising=exc.RuntimeError)
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return (
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ffi.buffer(pk, crypto_sign_PUBLICKEYBYTES)[:],
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ffi.buffer(sk, crypto_sign_SECRETKEYBYTES)[:],
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)
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def crypto_sign_seed_keypair(seed):
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"""
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Computes and returns the public key and secret key using the seed ``seed``.
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:param seed: bytes
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:rtype: (bytes(public_key), bytes(secret_key))
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"""
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if len(seed) != crypto_sign_SEEDBYTES:
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raise exc.ValueError("Invalid seed")
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pk = ffi.new("unsigned char[]", crypto_sign_PUBLICKEYBYTES)
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sk = ffi.new("unsigned char[]", crypto_sign_SECRETKEYBYTES)
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rc = lib.crypto_sign_seed_keypair(pk, sk, seed)
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ensure(rc == 0,
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'Unexpected library error',
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raising=exc.RuntimeError)
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return (
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ffi.buffer(pk, crypto_sign_PUBLICKEYBYTES)[:],
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ffi.buffer(sk, crypto_sign_SECRETKEYBYTES)[:],
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)
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def crypto_sign(message, sk):
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"""
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Signs the message ``message`` using the secret key ``sk`` and returns the
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signed message.
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:param message: bytes
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:param sk: bytes
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:rtype: bytes
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"""
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signed = ffi.new("unsigned char[]", len(message) + crypto_sign_BYTES)
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signed_len = ffi.new("unsigned long long *")
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rc = lib.crypto_sign(signed, signed_len, message, len(message), sk)
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ensure(rc == 0,
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'Unexpected library error',
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raising=exc.RuntimeError)
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return ffi.buffer(signed, signed_len[0])[:]
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def crypto_sign_open(signed, pk):
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"""
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Verifies the signature of the signed message ``signed`` using the public
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key ``pk`` and returns the unsigned message.
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:param signed: bytes
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:param pk: bytes
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:rtype: bytes
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"""
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message = ffi.new("unsigned char[]", len(signed))
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message_len = ffi.new("unsigned long long *")
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if lib.crypto_sign_open(
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message, message_len, signed, len(signed), pk) != 0:
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raise exc.BadSignatureError("Signature was forged or corrupt")
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return ffi.buffer(message, message_len[0])[:]
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def crypto_sign_ed25519_pk_to_curve25519(public_key_bytes):
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"""
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Converts a public Ed25519 key (encoded as bytes ``public_key_bytes``) to
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a public Curve25519 key as bytes.
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Raises a ValueError if ``public_key_bytes`` is not of length
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``crypto_sign_PUBLICKEYBYTES``
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:param public_key_bytes: bytes
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:rtype: bytes
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"""
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if len(public_key_bytes) != crypto_sign_PUBLICKEYBYTES:
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raise exc.ValueError("Invalid curve public key")
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curve_public_key_len = crypto_sign_curve25519_BYTES
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curve_public_key = ffi.new("unsigned char[]", curve_public_key_len)
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rc = lib.crypto_sign_ed25519_pk_to_curve25519(curve_public_key,
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public_key_bytes)
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ensure(rc == 0,
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'Unexpected library error',
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raising=exc.RuntimeError)
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return ffi.buffer(curve_public_key, curve_public_key_len)[:]
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def crypto_sign_ed25519_sk_to_curve25519(secret_key_bytes):
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"""
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Converts a secret Ed25519 key (encoded as bytes ``secret_key_bytes``) to
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a secret Curve25519 key as bytes.
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Raises a ValueError if ``secret_key_bytes``is not of length
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``crypto_sign_SECRETKEYBYTES``
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:param public_key_bytes: bytes
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:rtype: bytes
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"""
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if len(secret_key_bytes) != crypto_sign_SECRETKEYBYTES:
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raise exc.ValueError("Invalid curve public key")
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curve_secret_key_len = crypto_sign_curve25519_BYTES
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curve_secret_key = ffi.new("unsigned char[]", curve_secret_key_len)
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rc = lib.crypto_sign_ed25519_sk_to_curve25519(curve_secret_key,
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secret_key_bytes)
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ensure(rc == 0,
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'Unexpected library error',
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raising=exc.RuntimeError)
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return ffi.buffer(curve_secret_key, curve_secret_key_len)[:]
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class crypto_sign_ed25519ph_state(object):
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"""
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State object wrapping the sha-512 state used in ed25519ph computation
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"""
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__slots__ = ['state']
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def __init__(self):
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self.state = ffi.new('unsigned char[]',
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crypto_sign_ed25519ph_STATEBYTES)
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rc = lib.crypto_sign_ed25519ph_init(self.state)
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ensure(rc == 0,
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'Unexpected library error',
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raising=exc.RuntimeError)
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def crypto_sign_ed25519ph_update(edph, pmsg):
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"""
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Update the hash state wrapped in edph
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:param edph: the ed25519ph state being updated
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:type edph: crypto_sign_ed25519ph_state
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:param pmsg: the partial message
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:type pmsg: bytes
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:rtype: None
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"""
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ensure(isinstance(edph, crypto_sign_ed25519ph_state),
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'edph parameter must be a ed25519ph_state object',
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raising=exc.TypeError)
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ensure(isinstance(pmsg, bytes),
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'pmsg parameter must be a bytes object',
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raising=exc.TypeError)
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rc = lib.crypto_sign_ed25519ph_update(edph.state,
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pmsg,
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len(pmsg))
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ensure(rc == 0,
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'Unexpected library error',
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raising=exc.RuntimeError)
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def crypto_sign_ed25519ph_final_create(edph,
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sk):
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"""
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Create a signature for the data hashed in edph
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using the secret key sk
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:param edph: the ed25519ph state for the data
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being signed
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:type edph: crypto_sign_ed25519ph_state
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:param sk: the ed25519 secret part of the signing key
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:type sk: bytes
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:return: ed25519ph signature
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:rtype: bytes
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"""
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ensure(isinstance(edph, crypto_sign_ed25519ph_state),
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'edph parameter must be a ed25519ph_state object',
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raising=exc.TypeError)
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ensure(isinstance(sk, bytes),
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'secret key parameter must be a bytes object',
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raising=exc.TypeError)
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ensure(len(sk) == crypto_sign_SECRETKEYBYTES,
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('secret key must be {0} '
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'bytes long').format(crypto_sign_SECRETKEYBYTES),
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raising=exc.TypeError)
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signature = ffi.new("unsigned char[]", crypto_sign_BYTES)
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rc = lib.crypto_sign_ed25519ph_final_create(edph.state,
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signature,
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ffi.NULL,
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sk)
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ensure(rc == 0,
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'Unexpected library error',
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raising=exc.RuntimeError)
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return ffi.buffer(signature, crypto_sign_BYTES)[:]
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def crypto_sign_ed25519ph_final_verify(edph,
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signature,
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pk):
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"""
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Verify a prehashed signature using the public key pk
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:param edph: the ed25519ph state for the data
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being verified
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:type edph: crypto_sign_ed25519ph_state
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:param signature: the signature being verified
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:type signature: bytes
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:param pk: the ed25519 public part of the signing key
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:type pk: bytes
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:return: True if the signature is valid
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:rtype: boolean
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:raises exc.BadSignatureError: if the signature is not valid
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"""
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ensure(isinstance(edph, crypto_sign_ed25519ph_state),
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'edph parameter must be a ed25519ph_state object',
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raising=exc.TypeError)
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ensure(isinstance(signature, bytes),
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'signature parameter must be a bytes object',
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raising=exc.TypeError)
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ensure(len(signature) == crypto_sign_BYTES,
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('signature must be {0} '
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'bytes long').format(crypto_sign_BYTES),
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raising=exc.TypeError)
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ensure(isinstance(pk, bytes),
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'public key parameter must be a bytes object',
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raising=exc.TypeError)
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ensure(len(pk) == crypto_sign_PUBLICKEYBYTES,
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('public key must be {0} '
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'bytes long').format(crypto_sign_PUBLICKEYBYTES),
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raising=exc.TypeError)
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rc = lib.crypto_sign_ed25519ph_final_verify(edph.state,
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signature,
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pk)
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if rc != 0:
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raise exc.BadSignatureError("Signature was forged or corrupt")
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return True
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