func newPublicKeyCoords(x, y *big.Int) *PublicKey {
// Serialize coordinates
pk := new(PublicKey)
util.PaddedCopy(pk[:CoordinateSize], x.Bytes(), CoordinateSize)
util.PaddedCopy(pk[CoordinateSize:], y.Bytes(), CoordinateSize)
return pk
}
// Sign creates a signature on the hash under the given secret key.
func Sign(sk *eckey.SecretKey, hash []byte) (*Signature, error) {
// Generate random nonce
nonce:
k, kG, err := eckey.GenerateKeyPair()
if err != nil {
return nil, err
}
// Try again if kG is nil (point at infinity)
if kG == nil {
goto nonce
}
// Clear nonce after completion
defer k.Zero()
// Compute non-interactive challenge
e := util.Hash256d(append([]byte(hash), kG[:]...))
kInt := new(big.Int).SetBytes(k[:])
eInt := new(big.Int).SetBytes(e[:])
rInt := new(big.Int).SetBytes(sk[:])
// Compute s = k - er
s := new(big.Int)
s.Mul(eInt, rInt)
s.Sub(kInt, s)
s.Mod(s, eckey.S256.N)
// Serialize signature
sig := new(Signature)
copy(sig[:SignatureSize/2], e[:])
util.PaddedCopy(sig[SignatureSize/2:], s.Bytes(), SignatureSize/2)
return sig, nil
}
// computeChildSecret helper method that derives a child secret key from the
// intermediary state.
func (k *HDKey) computeChildSecret(ilInt *big.Int) *eckey.SecretKey {
keyInt := new(big.Int).SetBytes(k[childKeyOffset+1:])
defer keyInt.SetUint64(0)
ilInt.Add(ilInt, keyInt)
ilInt.Mod(ilInt, eckey.S256.N)
sk := new(eckey.SecretKey)
util.PaddedCopy(sk[:], ilInt.Bytes(), eckey.SecretSize)
return sk
}
func TestGenerateKeyPairDeterministic(t *testing.T) {
for _, test := range ecTestCases {
sk, pk := keyPairFromTestCase(test)
// Copy sk as entropy source
entropy := new(Entropy)
util.PaddedCopy(entropy[:], sk[:], EntropySize)
sk2, pk2 := GenerateKeyPairDeterministic(entropy)
// Secret keys should be the same
if bytes.Compare(sk[:], sk2[:]) != 0 {
t.Error("Failed to generate deterministic secret key")
continue
}
// Public keys should be the same
if bytes.Compare(pk[:], pk2[:]) != 0 {
t.Error("Failed to generate deterministic public key")
continue
}
}
}
func newSecretKeyInt(s *big.Int) *SecretKey {
sk := new(SecretKey)
util.PaddedCopy(sk[:], s.Bytes(), SecretSize)
return sk
}