47 lines
810 B
Go
47 lines
810 B
Go
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package main
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import (
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"crypto/sha1"
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"encoding/hex"
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"fmt"
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"strings"
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)
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func digest(secret, publicKey []byte) (string, error) {
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hash, err := func() (hash []byte, err error) {
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h := sha1.New()
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_, err = h.Write(secret)
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if err != nil {
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return nil, err
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}
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_, err = h.Write(publicKey)
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if err != nil {
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return nil, err
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}
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return h.Sum(nil), nil
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}()
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if err != nil {
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return "", fmt.Errorf("error writing sha1: %v", err)
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}
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var s strings.Builder
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if (hash[0] & 0x80) == 0x80 {
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hash = twosComplement(hash)
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s.WriteRune('-')
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}
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s.WriteString(strings.TrimLeft(hex.EncodeToString(hash), "0"))
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return s.String(), nil
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}
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func twosComplement(p []byte) []byte {
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carry := true
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for i := len(p) - 1; i >= 0; i-- {
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p[i] = ^p[i]
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if carry {
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carry = p[i] == 0xff
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p[i]++
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}
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}
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return p
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}
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