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Merge pull request #11 from nspcc-dev/fix/31-bytes-r-s

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Add leading zeros if `r` or `s` has less than 32 bytes
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Alex Vanin 2020-03-02 13:46:38 +03:00 committed by GitHub
commit ea3b6d784b
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 33 additions and 1 deletions
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13
rfc6979.go
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@ -38,7 +38,18 @@ func SignRFC6979(key *ecdsa.PrivateKey, msg []byte) ([]byte, error) {
return nil, ErrEmptyPrivateKey
}
r, s := rfc6979.SignECDSA(key, hashBytesRFC6979(msg), sha256.New)
return append(r.Bytes(), s.Bytes()...), nil
rBytes, sBytes := r.Bytes(), s.Bytes()
signature := make([]byte, RFC6979SignatureSize)
// if `r` has less than 32 bytes, add leading zeros
ind := RFC6979SignatureSize/2 - len(rBytes)
copy(signature[ind:], rBytes)
// if `s` has less than 32 bytes, add leading zeros
ind = RFC6979SignatureSize - len(sBytes)
copy(signature[ind:], sBytes)
return signature, nil
}
func decodeSignature(sig []byte) (*big.Int, *big.Int, error) {

21
rfc6979_test.go
View file

@ -4,6 +4,7 @@ import (
"encoding/hex"
"testing"
"github.com/nspcc-dev/neofs-crypto/test"
"github.com/stretchr/testify/require"
)
@ -83,3 +84,23 @@ func TestRFC6979(t *testing.T) {
}
}
}
func TestRFC6979_ShortDecodePoints(t *testing.T) {
key := test.DecodeKey(1)
msgs := []string{
"6341922933e156ea5a53b8ea3fa4a80c", // this msg has 31 byte `s` point
"61b863d81f72e0e0d0353b1cb90d62ce", // this msg has 31 byte 'r' point
}
for i := range msgs {
msg, err := hex.DecodeString(msgs[i])
require.NoError(t, err)
signature, err := SignRFC6979(key, msg)
require.NoError(t, err, msgs[i])
err = VerifyRFC6979(&key.PublicKey, msg, signature)
require.NoError(t, err, msgs[i])
}
}