38 lines
1.2 KiB
Python
38 lines
1.2 KiB
Python
from __future__ import annotations
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from os import urandom
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from threading import Lock
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from coincurve._libsecp256k1 import ffi, lib
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from coincurve.flags import CONTEXT_FLAGS, CONTEXT_NONE
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class Context:
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def __init__(self, seed: bytes | None = None, flag=CONTEXT_NONE, name: str = ""):
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if flag not in CONTEXT_FLAGS:
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msg = f"{flag} is an invalid context flag."
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raise ValueError(msg)
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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 = 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 # noqa: PLR2004
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res = lib.secp256k1_context_randomize(self.ctx, ffi.new("unsigned char [32]", seed))
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if not res:
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msg = "secp256k1_context_randomize"
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raise ValueError(msg)
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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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