Two factor authentication support (#630)

* Initial commit for 2FA support

Signed-off-by: Andrew <write@imaginarycode.com>

* Add vendored files

* Add missing depends

* A few clean ups

* Added improvements, proper encryption

* Better encryption key

* Simplify "key" generation

* Make 2FA enrollment page more robust

* Fix typo

* Rename twofa/2FA to TwoFactor

* UNIQUE INDEX -> UNIQUE

vendor/github.com/boombuler/barcode/utils/galoisfield.go

@@ -0,0 +1,65 @@
+package utils
+
+// GaloisField encapsulates galois field arithmetics
+type GaloisField struct {
+	Size    int
+	Base    int
+	ALogTbl []int
+	LogTbl  []int
+}
+
+// NewGaloisField creates a new galois field
+func NewGaloisField(pp, fieldSize, b int) *GaloisField {
+	result := new(GaloisField)
+
+	result.Size = fieldSize
+	result.Base = b
+	result.ALogTbl = make([]int, fieldSize)
+	result.LogTbl = make([]int, fieldSize)
+
+	x := 1
+	for i := 0; i < fieldSize; i++ {
+		result.ALogTbl[i] = x
+		x = x * 2
+		if x >= fieldSize {
+			x = (x ^ pp) & (fieldSize - 1)
+		}
+	}
+
+	for i := 0; i < fieldSize; i++ {
+		result.LogTbl[result.ALogTbl[i]] = int(i)
+	}
+
+	return result
+}
+
+func (gf *GaloisField) Zero() *GFPoly {
+	return NewGFPoly(gf, []int{0})
+}
+
+// AddOrSub add or substract two numbers
+func (gf *GaloisField) AddOrSub(a, b int) int {
+	return a ^ b
+}
+
+// Multiply multiplys two numbers
+func (gf *GaloisField) Multiply(a, b int) int {
+	if a == 0 || b == 0 {
+		return 0
+	}
+	return gf.ALogTbl[(gf.LogTbl[a]+gf.LogTbl[b])%(gf.Size-1)]
+}
+
+// Divide divides two numbers
+func (gf *GaloisField) Divide(a, b int) int {
+	if b == 0 {
+		panic("divide by zero")
+	} else if a == 0 {
+		return 0
+	}
+	return gf.ALogTbl[(gf.LogTbl[a]-gf.LogTbl[b])%(gf.Size-1)]
+}
+
+func (gf *GaloisField) Invers(num int) int {
+	return gf.ALogTbl[(gf.Size-1)-gf.LogTbl[num]]
+}