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33 lines
1015 B
33 lines
1015 B
from os import urandom
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from threading import Lock
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from coincurve.flags import CONTEXT_ALL, CONTEXT_FLAGS
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from ._libsecp256k1 import ffi, lib
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class Context:
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def __init__(self, seed: bytes = None, flag=CONTEXT_ALL, name: str = ''):
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if flag not in CONTEXT_FLAGS:
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raise ValueError('{} is an invalid context flag.'.format(flag))
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self._lock = Lock()
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self.ctx = ffi.gc(lib.secp256k1_context_create(flag), lib.secp256k1_context_destroy)
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self.reseed(seed)
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self.name = name
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def reseed(self, seed: bytes = None):
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"""
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Protects against certain possible future side-channel timing attacks.
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"""
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with self._lock:
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seed = urandom(32) if not seed or len(seed) != 32 else seed
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res = lib.secp256k1_context_randomize(self.ctx, ffi.new('unsigned char [32]', seed))
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assert res == 1
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def __repr__(self):
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return self.name or super().__repr__()
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GLOBAL_CONTEXT = Context(name='GLOBAL_CONTEXT')
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