83 lines
1.3 KiB
Go
83 lines
1.3 KiB
Go
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package types
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import (
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"bytes"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/status-im/keycard-go/apdu"
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)
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var (
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TagSignatureTemplate = uint8(0xA0)
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)
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type Signature struct {
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pubKey []byte
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r []byte
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s []byte
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v byte
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}
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func ParseSignature(message, resp []byte) (*Signature, error) {
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pubKey, err := apdu.FindTag(resp, TagSignatureTemplate, uint8(0x80))
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if err != nil {
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return nil, err
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}
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r, err := apdu.FindTagN(resp, 0, TagSignatureTemplate, uint8(0x30), uint8(0x02))
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if err != nil {
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return nil, err
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}
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if len(r) > 32 {
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r = r[len(r)-32:]
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}
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s, err := apdu.FindTagN(resp, 1, TagSignatureTemplate, uint8(0x30), uint8(0x02))
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if err != nil {
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return nil, err
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}
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v, err := calculateV(message, pubKey, r, s)
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if err != nil {
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return nil, err
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}
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return &Signature{
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pubKey: pubKey,
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r: r,
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s: s,
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v: v,
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}, nil
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}
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func (s *Signature) R() []byte {
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return s.r
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}
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func (s *Signature) S() []byte {
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return s.s
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}
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func (s *Signature) V() byte {
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return s.v
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}
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func calculateV(message, pubKey, r, s []byte) (v byte, err error) {
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rs := append(r, s...)
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for i := 0; i < 2; i++ {
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v = byte(i)
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sig := append(rs, v)
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rec, err := crypto.Ecrecover(message, sig)
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if err != nil {
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return v, err
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}
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if bytes.Equal(pubKey, rec) {
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return v, nil
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}
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}
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return v, err
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}
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