75 lines
1.7 KiB
Go
75 lines
1.7 KiB
Go
package colorhash
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import (
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"math/big"
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"github.com/status-im/status-go/multiaccounts"
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"github.com/status-im/status-go/protocol/identity"
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)
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const (
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colorHashSegmentMaxLen = 5
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colorHashColorsCount = 32
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)
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var colorHashAlphabet [][]int
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func GenerateFor(pubkey string) (hash multiaccounts.ColorHash, err error) {
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if len(colorHashAlphabet) == 0 {
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colorHashAlphabet = makeColorHashAlphabet(colorHashSegmentMaxLen, colorHashColorsCount)
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}
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compressedKey, err := identity.ToCompressedKey(pubkey)
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if err != nil {
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return nil, err
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}
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slices, err := identity.Slices(compressedKey)
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if err != nil {
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return nil, err
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}
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return toColorHash(new(big.Int).SetBytes(slices[2]), &colorHashAlphabet, colorHashColorsCount), nil
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}
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// [[1 0] [1 1] [1 2] ... [units, colors-1]]
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// [3 12] => 3 units length, 12 color index
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func makeColorHashAlphabet(units, colors int) (res [][]int) {
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res = make([][]int, units*colors)
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idx := 0
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for i := 0; i < units; i++ {
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for j := 0; j < colors; j++ {
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res[idx] = make([]int, 2)
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res[idx][0] = i + 1
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res[idx][1] = j
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idx++
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}
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}
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return
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}
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func toColorHash(value *big.Int, alphabet *[][]int, colorsCount int) (hash multiaccounts.ColorHash) {
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alphabetLen := len(*alphabet)
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indexes := identity.ToBigBase(value, uint64(alphabetLen))
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hash = make(multiaccounts.ColorHash, len(indexes))
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for i, v := range indexes {
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hash[i] = [2]int{}
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hash[i][0] = (*alphabet)[v][0]
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hash[i][1] = (*alphabet)[v][1]
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}
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// colors can't repeat themselves
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// this makes color hash not fully collision resistant
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prevColorIdx := hash[0][1]
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hashLen := len(hash)
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for i := 1; i < hashLen; i++ {
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colorIdx := hash[i][1]
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if colorIdx == prevColorIdx {
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hash[i][1] = (colorIdx + 1) % colorsCount
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}
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prevColorIdx = hash[i][1]
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}
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return
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}
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