forked from TrueCloudLab/neoneo-go
59 lines
1.3 KiB
Go
Executable file
59 lines
1.3 KiB
Go
Executable file
package rfc6979
|
|
|
|
import (
|
|
"hash"
|
|
"math/big"
|
|
|
|
"github.com/CityOfZion/neo-go/pkg/crypto/elliptic"
|
|
)
|
|
|
|
// SignECDSA signs an arbitrary length hash (which should be the result of
|
|
// hashing a larger message) using the private key, priv. It returns the
|
|
// signature as a pair of integers.
|
|
//
|
|
// Note that FIPS 186-3 section 4.6 specifies that the hash should be truncated
|
|
// to the byte-length of the subgroup. This function does not perform that
|
|
// truncation itself.
|
|
func SignECDSA(curve elliptic.Curve, priv []byte, hash []byte, alg func() hash.Hash) (r, s *big.Int, err error) {
|
|
c := curve
|
|
N := c.N
|
|
D := new(big.Int)
|
|
D.SetBytes(priv)
|
|
generateSecret(N, D, alg, hash, func(k *big.Int) bool {
|
|
|
|
inv := new(big.Int).ModInverse(k, N)
|
|
|
|
r, _ = curve.ScalarBaseMult(k.Bytes())
|
|
r.Mod(r, N)
|
|
|
|
if r.Sign() == 0 {
|
|
return false
|
|
}
|
|
|
|
e := hashToInt(hash, c)
|
|
s = new(big.Int).Mul(D, r)
|
|
s.Add(s, e)
|
|
s.Mul(s, inv)
|
|
s.Mod(s, N)
|
|
|
|
return s.Sign() != 0
|
|
})
|
|
|
|
return
|
|
}
|
|
|
|
// copied from crypto/ecdsa
|
|
func hashToInt(hash []byte, c elliptic.Curve) *big.Int {
|
|
orderBits := c.N.BitLen()
|
|
orderBytes := (orderBits + 7) / 8
|
|
if len(hash) > orderBytes {
|
|
hash = hash[:orderBytes]
|
|
}
|
|
|
|
ret := new(big.Int).SetBytes(hash)
|
|
excess := len(hash)*8 - orderBits
|
|
if excess > 0 {
|
|
ret.Rsh(ret, uint(excess))
|
|
}
|
|
return ret
|
|
}
|