59 lines
1.9 KiB
Python
59 lines
1.9 KiB
Python
import hashlib
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import secrets
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from datetime import timedelta
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from django.utils import timezone
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from infrasynth.shared.settings_utils import get_setting
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from ..models import ALTCHAChallenge
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class ALTCHAService:
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"""Proof-of-work challenge for anti-spam protection."""
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def create_challenge(self) -> dict:
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difficulty = get_setting("INFRASYNTH_SECURITY", "ALTCHA_DIFFICULTY", 10000)
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expiry_seconds = get_setting("INFRASYNTH_SECURITY", "ALTCHA_CHALLENGE_EXPIRY_SECONDS", 300)
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challenge_id = secrets.token_hex(32)
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salt = secrets.token_hex(16)
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expires_at = timezone.now() + timedelta(seconds=expiry_seconds)
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ALTCHAChallenge.objects.create(
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challenge_id=challenge_id,
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salt=salt,
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difficulty=difficulty,
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expires_at=expires_at,
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)
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return {
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"challenge_id": challenge_id,
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"salt": salt,
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"difficulty": difficulty,
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"algorithm": "SHA-256",
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}
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def verify(self, challenge_id: str, solution: str, number: int) -> bool:
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try:
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challenge = ALTCHAChallenge.objects.get(challenge_id=challenge_id, is_verified=False)
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except ALTCHAChallenge.DoesNotExist:
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return False
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if challenge.expires_at < timezone.now():
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return False
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expected = hashlib.sha256(f"{challenge.salt}{number}".encode()).hexdigest()
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if solution != expected:
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return False
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challenge.is_verified = True
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challenge.save(update_fields=["is_verified"])
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return True
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def compute_solution(self, salt: str, difficulty: int) -> tuple[str, int]:
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number = 0
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while True:
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h = hashlib.sha256(f"{salt}{number}".encode()).hexdigest()
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if h.startswith("0" * (difficulty // 10000)):
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return h, number
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number += 1
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