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/bitlist.go

@@ -0,0 +1,119 @@
+package utils
+
+// BitList is a list that contains bits
+type BitList struct {
+	count int
+	data  []int32
+}
+
+// NewBitList returns a new BitList with the given length
+// all bits are initialize with false
+func NewBitList(capacity int) *BitList {
+	bl := new(BitList)
+	bl.count = capacity
+	x := 0
+	if capacity%32 != 0 {
+		x = 1
+	}
+	bl.data = make([]int32, capacity/32+x)
+	return bl
+}
+
+// Len returns the number of contained bits
+func (bl *BitList) Len() int {
+	return bl.count
+}
+
+func (bl *BitList) grow() {
+	growBy := len(bl.data)
+	if growBy < 128 {
+		growBy = 128
+	} else if growBy >= 1024 {
+		growBy = 1024
+	}
+
+	nd := make([]int32, len(bl.data)+growBy)
+	copy(nd, bl.data)
+	bl.data = nd
+}
+
+// AddBit appends the given bits to the end of the list
+func (bl *BitList) AddBit(bits ...bool) {
+	for _, bit := range bits {
+		itmIndex := bl.count / 32
+		for itmIndex >= len(bl.data) {
+			bl.grow()
+		}
+		bl.SetBit(bl.count, bit)
+		bl.count++
+	}
+}
+
+// SetBit sets the bit at the given index to the given value
+func (bl *BitList) SetBit(index int, value bool) {
+	itmIndex := index / 32
+	itmBitShift := 31 - (index % 32)
+	if value {
+		bl.data[itmIndex] = bl.data[itmIndex] | 1<<uint(itmBitShift)
+	} else {
+		bl.data[itmIndex] = bl.data[itmIndex] & ^(1 << uint(itmBitShift))
+	}
+}
+
+// GetBit returns the bit at the given index
+func (bl *BitList) GetBit(index int) bool {
+	itmIndex := index / 32
+	itmBitShift := 31 - (index % 32)
+	return ((bl.data[itmIndex] >> uint(itmBitShift)) & 1) == 1
+}
+
+// AddByte appends all 8 bits of the given byte to the end of the list
+func (bl *BitList) AddByte(b byte) {
+	for i := 7; i >= 0; i-- {
+		bl.AddBit(((b >> uint(i)) & 1) == 1)
+	}
+}
+
+// AddBits appends the last (LSB) 'count' bits of 'b' the the end of the list
+func (bl *BitList) AddBits(b int, count byte) {
+	for i := int(count) - 1; i >= 0; i-- {
+		bl.AddBit(((b >> uint(i)) & 1) == 1)
+	}
+}
+
+// GetBytes returns all bits of the BitList as a []byte
+func (bl *BitList) GetBytes() []byte {
+	len := bl.count >> 3
+	if (bl.count % 8) != 0 {
+		len++
+	}
+	result := make([]byte, len)
+	for i := 0; i < len; i++ {
+		shift := (3 - (i % 4)) * 8
+		result[i] = (byte)((bl.data[i/4] >> uint(shift)) & 0xFF)
+	}
+	return result
+}
+
+// IterateBytes iterates through all bytes contained in the BitList
+func (bl *BitList) IterateBytes() <-chan byte {
+	res := make(chan byte)
+
+	go func() {
+		c := bl.count
+		shift := 24
+		i := 0
+		for c > 0 {
+			res <- byte((bl.data[i] >> uint(shift)) & 0xFF)
+			shift -= 8
+			if shift < 0 {
+				shift = 24
+				i++
+			}
+			c -= 8
+		}
+		close(res)
+	}()
+
+	return res
+}