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#!/usr/bin/env python3
# Copyright (c) 2016-2022 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""SipHash-2-4 implementation.
This implements SipHash-2-4. For convenience, an interface taking 256-bit
integers is provided in addition to the one accepting generic data.
"""
def rotl64(n, b):
return n >> (64 - b) | (n & ((1 << (64 - b)) - 1)) << b
def siphash_round(v0, v1, v2, v3):
v0 = (v0 + v1) & ((1 << 64) - 1)
v1 = rotl64(v1, 13)
v1 ^= v0
v0 = rotl64(v0, 32)
v2 = (v2 + v3) & ((1 << 64) - 1)
v3 = rotl64(v3, 16)
v3 ^= v2
v0 = (v0 + v3) & ((1 << 64) - 1)
v3 = rotl64(v3, 21)
v3 ^= v0
v2 = (v2 + v1) & ((1 << 64) - 1)
v1 = rotl64(v1, 17)
v1 ^= v2
v2 = rotl64(v2, 32)
return (v0, v1, v2, v3)
def siphash(k0, k1, data):
assert type(data) == bytes
v0 = 0x736f6d6570736575 ^ k0
v1 = 0x646f72616e646f6d ^ k1
v2 = 0x6c7967656e657261 ^ k0
v3 = 0x7465646279746573 ^ k1
c = 0
t = 0
for d in data:
t |= d << (8 * (c % 8))
c = (c + 1) & 0xff
if (c & 7) == 0:
v3 ^= t
v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
v0 ^= t
t = 0
t = t | (c << 56)
v3 ^= t
v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
v0 ^= t
v2 ^= 0xff
v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
v0, v1, v2, v3 = siphash_round(v0, v1, v2, v3)
return v0 ^ v1 ^ v2 ^ v3
def siphash256(k0, k1, num):
assert type(num) == int
return siphash(k0, k1, num.to_bytes(32, 'little'))
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