yaole
104 lines
1.8 KiB
Go
104 lines
1.8 KiB
Go
// package ope is the Order-Preserving Encryption
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// 保序加密, 即保持密文的顺序. 可用于数据库.
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package ope
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func bytesToCoins(b []byte) []byte {
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res := make([]byte, 0, 8*len(b))
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for _, x := range b {
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for i := 0; i < 8; i++ {
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res = append(res, x&1)
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x >>= 1
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}
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}
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return res
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}
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// ValueRange reprents the range [start, end]
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type ValueRange struct {
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start int64
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end int64
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}
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func (v *ValueRange) Set(start int64, end int64) *ValueRange {
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if start > end {
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panic("not a valid value range, start must no greater then end")
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}
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v.start = start
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v.end = end
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return v
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}
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func (v *ValueRange) Size() int64 {
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return v.end - v.start + 1
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}
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func (v *ValueRange) Contains(n int64) bool {
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return n >= v.start && n <= v.end
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}
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// func (v *ValueRange) BitSize() int64 {
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// n := v.Size()
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// return int64(n.BitLen())
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// }
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func (v *ValueRange) Clone() *ValueRange {
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return new(ValueRange).Set(v.start, v.end)
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}
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// UniformRand returns a number in range uniformly
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func UniformRand(M *ValueRange, coins []byte) int64 {
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start, end := M.start, M.end
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for i := 0; end > start; i++ {
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mid := (start + end) / 2
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if coins[i] == 0 {
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end = mid
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} else {
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start = mid + 1
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}
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}
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return start
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}
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// HyperGeometricRand returns a number x in inRange, satisfying the distribution
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// Prob[X = x] = HyperGeometric(M, N, y)
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func HyperGeometricRand(M, N *ValueRange, y int64, coins []byte) int64 {
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m := M.Size()
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n := N.Size()
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nsampleIndex := y - N.start + 1
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if M == N {
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return M.start + nsampleIndex - 1
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}
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inSampleNum := hypergeometric(m, n, nsampleIndex, coins)
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if inSampleNum == 0 {
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return M.start
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} else {
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return M.start + inSampleNum - 1
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}
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}
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type OPE struct {
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}
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func (o *OPE) Init(key []byte) {
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}
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func (o *OPE) Encrypt() {
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}
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func (o *OPE) Decrypts() {
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}
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func tapeGen(key []byte, data []byte) []byte {
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return nil
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}
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func sampleUniform() {
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}
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