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/gfpoly.go

@@ -0,0 +1,103 @@
+package utils
+
+type GFPoly struct {
+	gf           *GaloisField
+	Coefficients []int
+}
+
+func (gp *GFPoly) Degree() int {
+	return len(gp.Coefficients) - 1
+}
+
+func (gp *GFPoly) Zero() bool {
+	return gp.Coefficients[0] == 0
+}
+
+// GetCoefficient returns the coefficient of x ^ degree
+func (gp *GFPoly) GetCoefficient(degree int) int {
+	return gp.Coefficients[gp.Degree()-degree]
+}
+
+func (gp *GFPoly) AddOrSubstract(other *GFPoly) *GFPoly {
+	if gp.Zero() {
+		return other
+	} else if other.Zero() {
+		return gp
+	}
+	smallCoeff := gp.Coefficients
+	largeCoeff := other.Coefficients
+	if len(smallCoeff) > len(largeCoeff) {
+		largeCoeff, smallCoeff = smallCoeff, largeCoeff
+	}
+	sumDiff := make([]int, len(largeCoeff))
+	lenDiff := len(largeCoeff) - len(smallCoeff)
+	copy(sumDiff, largeCoeff[:lenDiff])
+	for i := lenDiff; i < len(largeCoeff); i++ {
+		sumDiff[i] = int(gp.gf.AddOrSub(int(smallCoeff[i-lenDiff]), int(largeCoeff[i])))
+	}
+	return NewGFPoly(gp.gf, sumDiff)
+}
+
+func (gp *GFPoly) MultByMonominal(degree int, coeff int) *GFPoly {
+	if coeff == 0 {
+		return gp.gf.Zero()
+	}
+	size := len(gp.Coefficients)
+	result := make([]int, size+degree)
+	for i := 0; i < size; i++ {
+		result[i] = int(gp.gf.Multiply(int(gp.Coefficients[i]), int(coeff)))
+	}
+	return NewGFPoly(gp.gf, result)
+}
+
+func (gp *GFPoly) Multiply(other *GFPoly) *GFPoly {
+	if gp.Zero() || other.Zero() {
+		return gp.gf.Zero()
+	}
+	aCoeff := gp.Coefficients
+	aLen := len(aCoeff)
+	bCoeff := other.Coefficients
+	bLen := len(bCoeff)
+	product := make([]int, aLen+bLen-1)
+	for i := 0; i < aLen; i++ {
+		ac := int(aCoeff[i])
+		for j := 0; j < bLen; j++ {
+			bc := int(bCoeff[j])
+			product[i+j] = int(gp.gf.AddOrSub(int(product[i+j]), gp.gf.Multiply(ac, bc)))
+		}
+	}
+	return NewGFPoly(gp.gf, product)
+}
+
+func (gp *GFPoly) Divide(other *GFPoly) (quotient *GFPoly, remainder *GFPoly) {
+	quotient = gp.gf.Zero()
+	remainder = gp
+	fld := gp.gf
+	denomLeadTerm := other.GetCoefficient(other.Degree())
+	inversDenomLeadTerm := fld.Invers(int(denomLeadTerm))
+	for remainder.Degree() >= other.Degree() && !remainder.Zero() {
+		degreeDiff := remainder.Degree() - other.Degree()
+		scale := int(fld.Multiply(int(remainder.GetCoefficient(remainder.Degree())), inversDenomLeadTerm))
+		term := other.MultByMonominal(degreeDiff, scale)
+		itQuot := NewMonominalPoly(fld, degreeDiff, scale)
+		quotient = quotient.AddOrSubstract(itQuot)
+		remainder = remainder.AddOrSubstract(term)
+	}
+	return
+}
+
+func NewMonominalPoly(field *GaloisField, degree int, coeff int) *GFPoly {
+	if coeff == 0 {
+		return field.Zero()
+	}
+	result := make([]int, degree+1)
+	result[0] = coeff
+	return NewGFPoly(field, result)
+}
+
+func NewGFPoly(field *GaloisField, coefficients []int) *GFPoly {
+	for len(coefficients) > 1 && coefficients[0] == 0 {
+		coefficients = coefficients[1:]
+	}
+	return &GFPoly{field, coefficients}
+}