init: v1.0.0

x/ope/ope.go

@@ -0,0 +1,103 @@
+// package ope is the Order-Preserving Encryption
+// 保序加密, 即保持密文的顺序. 可用于数据库.
+package ope
+
+func bytesToCoins(b []byte) []byte {
+	res := make([]byte, 0, 8*len(b))
+	for _, x := range b {
+		for i := 0; i < 8; i++ {
+			res = append(res, x&1)
+			x >>= 1
+		}
+	}
+	return res
+}
+
+// ValueRange reprents the range [start, end]
+type ValueRange struct {
+	start int64
+	end   int64
+}
+
+func (v *ValueRange) Set(start int64, end int64) *ValueRange {
+	if start > end {
+		panic("not a valid value range, start must no greater then end")
+	}
+	v.start = start
+	v.end = end
+	return v
+}
+
+func (v *ValueRange) Size() int64 {
+	return v.end - v.start + 1
+}
+
+func (v *ValueRange) Contains(n int64) bool {
+	return n >= v.start && n <= v.end
+}
+
+// func (v *ValueRange) BitSize() int64 {
+// 	n := v.Size()
+// 	return int64(n.BitLen())
+// }
+
+func (v *ValueRange) Clone() *ValueRange {
+	return new(ValueRange).Set(v.start, v.end)
+}
+
+// UniformRand returns a number in range uniformly
+func UniformRand(M *ValueRange, coins []byte) int64 {
+	start, end := M.start, M.end
+	for i := 0; end > start; i++ {
+		mid := (start + end) / 2
+		if coins[i] == 0 {
+			end = mid
+		} else {
+			start = mid + 1
+		}
+	}
+	return start
+}
+
+// HyperGeometricRand returns a number x in inRange, satisfying the distribution
+// Prob[X = x] = HyperGeometric(M, N, y)
+func HyperGeometricRand(M, N *ValueRange, y int64, coins []byte) int64 {
+	m := M.Size()
+	n := N.Size()
+
+	nsampleIndex := y - N.start + 1
+	if M == N {
+		return M.start + nsampleIndex - 1
+	}
+
+	inSampleNum := hypergeometric(m, n, nsampleIndex, coins)
+	if inSampleNum == 0 {
+		return M.start
+	} else {
+		return M.start + inSampleNum - 1
+	}
+}
+
+type OPE struct {
+}
+
+func (o *OPE) Init(key []byte) {
+
+}
+
+func (o *OPE) Encrypt() {
+
+}
+
+func (o *OPE) Decrypts() {
+
+}
+
+func tapeGen(key []byte, data []byte) []byte {
+	return nil
+
+}
+
+func sampleUniform() {
+
+}