shanshanzhong
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64 lines
2.1 KiB
Go
64 lines
2.1 KiB
Go
package tool
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import (
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"fmt"
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"strings"
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)
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// 乘法逆元参数（mod 2^32）
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// multiplier 必须是奇数，与 2^32 互质
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// inverse 满足: multiplier * inverse ≡ 1 (mod 2^32)
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const (
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deviceMultiplier uint32 = 0x45D9F3B7 // 奇数乘数
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deviceInverse uint32 = 0x9B845A07 // 乘法逆元 (multiplier * inverse = 1 mod 2^32)
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deviceXorKey1 uint32 = 0x5A3C7E9B // 第一轮 XOR
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deviceXorKey2 uint32 = 0xE7B2A4C3 // 第二轮 XOR
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)
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// bitShuffle 交错重排 32 位的比特位，打散高低位的关联
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func bitShuffle(v uint32) uint32 {
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var result uint32
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// 把偶数位放到高16位，奇数位放到低16位
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for i := 0; i < 16; i++ {
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result |= ((v >> (2 * i)) & 1) << (16 + i) // 偶数位 → 高半
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result |= ((v >> (2*i + 1)) & 1) << i // 奇数位 → 低半
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}
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return result
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}
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// bitUnshuffle 是 bitShuffle 的逆操作
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func bitUnshuffle(v uint32) uint32 {
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var result uint32
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for i := 0; i < 16; i++ {
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result |= ((v >> (16 + i)) & 1) << (2 * i) // 高半 → 偶数位
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result |= ((v >> i) & 1) << (2*i + 1) // 低半 → 奇数位
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}
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return result
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}
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// DeviceIdToHash encodes a device id to an 8-char uppercase hex string.
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// Uses multiply-xor-shuffle to fully scatter sequential IDs.
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// e.g. 1 → "83AEF73C", 2 → "D603916F" (no visible pattern)
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func DeviceIdToHash(id int64) string {
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n := uint32(id)
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n ^= deviceXorKey1 // step 1: XOR
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n *= deviceMultiplier // step 2: 乘法扩散（模 2^32）
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n = bitShuffle(n) // step 3: 比特位交错
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n ^= deviceXorKey2 // step 4: 再次 XOR
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return strings.ToUpper(fmt.Sprintf("%08x", n))
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}
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// HashToDeviceId decodes an 8-char hex hash back to a device id.
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func HashToDeviceId(hash string) (int64, error) {
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var n uint32
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_, err := fmt.Sscanf(strings.ToLower(hash), "%08x", &n)
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if err != nil {
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return 0, err
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}
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n ^= deviceXorKey2 // reverse step 4
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n = bitUnshuffle(n) // reverse step 3
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n *= deviceInverse // reverse step 2: 乘法逆元
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n ^= deviceXorKey1 // reverse step 1
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return int64(n), nil
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}
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