vikunja-api/vendor/github.com/boombuler/barcode/utils/gfpoly.go
konrad 24904585a2 Add 2fa for authentification (#383)
Fix user tests

Add swagger docs

Fix lint

Add totp check when logging in

Make totp enrollment work

Add migration for totp table

go mod vendor

Add routes for totp routes

Add route handler for totp routes

Add basic implementation to enroll a user in totp

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/api/pulls/383
2020-04-17 19:25:35 +00:00

103 lines
2.8 KiB
Go

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}
}