vikunja-api/vendor/github.com/boombuler/barcode/utils/galoisfield.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

65 lines
1.3 KiB
Go

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]]
}