mirror of
https://github.com/zerotier/lf.git
synced 2026-05-22 16:24:00 -07:00
Adam Ierymenko
41 lines
1.3 KiB
Go
41 lines
1.3 KiB
Go
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/.
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*
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* (c)2019-2021 ZeroTier, Inc.
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* https://www.zerotier.com/
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*/
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package lf
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import (
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"crypto/aes"
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"encoding/binary"
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"unsafe"
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)
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// AES for AES-MMO with an arbitrary random 128-bit key.
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var th64Aes, _ = aes.NewCipher([]byte{1, 200, 16, 93, 99, 101, 16, 4, 99, 202, 255, 254, 22, 17, 42, 173})
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// th64 computes a tiny 64-bit hash using AES in a simple Matyas-Meyer-Oseas construction.
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// See: https://en.wikipedia.org/wiki/One-way_compression_function#Matyas–Meyer–Oseas
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func th64(i uint64) uint64 {
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var in, out [16]byte
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binary.LittleEndian.PutUint64(in[0:8], i)
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th64Aes.Encrypt(out[:], in[:])
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return binary.LittleEndian.Uint64(out[0:8]) ^ binary.LittleEndian.Uint64(out[8:16]) ^ i
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}
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// th64n performs TH64 count times and is a bit faster than just repeatedly calling TH64.
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func th64n(i uint64, count uint) uint64 {
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var in, out [2]uint64
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inb := ((*[16]byte)(unsafe.Pointer(&in)))[:]
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outb := ((*[16]byte)(unsafe.Pointer(&out)))[:]
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binary.LittleEndian.PutUint64(inb[0:8], i)
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for k := uint(0); k < count; k++ {
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th64Aes.Encrypt(outb, inb)
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in[0] ^= out[0] ^ out[1]
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}
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return binary.LittleEndian.Uint64(inb[0:8])
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}
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