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package sr25519
import (
"encoding/json"
"fmt"
"io"
"github.com/oasisprotocol/curve25519-voi/primitives/sr25519"
"github.com/tendermint/tendermint/crypto"
)
var (
_ crypto.PrivKey = PrivKey{}
signingCtx = sr25519.NewSigningContext([]byte{})
)
const (
// PrivKeySize is the size of a sr25519 signature in bytes.
PrivKeySize = sr25519.MiniSecretKeySize
KeyType = "sr25519"
)
// PrivKey implements crypto.PrivKey.
type PrivKey struct {
msk sr25519.MiniSecretKey
kp *sr25519.KeyPair
}
// TypeTag satisfies the jsontypes.Tagged interface.
func (PrivKey) TypeTag() string { return PrivKeyName }
// Bytes returns the byte-encoded PrivKey.
func (privKey PrivKey) Bytes() []byte {
if privKey.kp == nil {
return nil
}
return privKey.msk[:]
}
// Sign produces a signature on the provided message.
func (privKey PrivKey) Sign(msg []byte) ([]byte, error) {
if privKey.kp == nil {
return nil, fmt.Errorf("sr25519: uninitialized private key")
}
st := signingCtx.NewTranscriptBytes(msg)
sig, err := privKey.kp.Sign(crypto.CReader(), st)
if err != nil {
return nil, fmt.Errorf("sr25519: failed to sign message: %w", err)
}
sigBytes, err := sig.MarshalBinary()
if err != nil {
return nil, fmt.Errorf("sr25519: failed to serialize signature: %w", err)
}
return sigBytes, nil
}
// PubKey gets the corresponding public key from the private key.
//
// Panics if the private key is not initialized.
func (privKey PrivKey) PubKey() crypto.PubKey {
if privKey.kp == nil {
panic("sr25519: uninitialized private key")
}
b, err := privKey.kp.PublicKey().MarshalBinary()
if err != nil {
panic("sr25519: failed to serialize public key: " + err.Error())
}
return PubKey(b)
}
// Equals - you probably don't need to use this.
// Runs in constant time based on length of the keys.
func (privKey PrivKey) Equals(other crypto.PrivKey) bool {
if otherSr, ok := other.(PrivKey); ok {
return privKey.msk.Equal(&otherSr.msk)
}
return false
}
func (privKey PrivKey) Type() string {
return KeyType
}
func (privKey PrivKey) MarshalJSON() ([]byte, error) {
var b []byte
// Handle uninitialized private keys gracefully.
if privKey.kp != nil {
b = privKey.Bytes()
}
return json.Marshal(b)
}
func (privKey *PrivKey) UnmarshalJSON(data []byte) error {
for i := range privKey.msk {
privKey.msk[i] = 0
}
privKey.kp = nil
var b []byte
if err := json.Unmarshal(data, &b); err != nil {
return fmt.Errorf("sr25519: failed to deserialize JSON: %w", err)
}
if len(b) == 0 {
return nil
}
msk, err := sr25519.NewMiniSecretKeyFromBytes(b)
if err != nil {
return err
}
sk := msk.ExpandEd25519()
privKey.msk = *msk
privKey.kp = sk.KeyPair()
return nil
}
// GenPrivKey generates a new sr25519 private key.
// It uses OS randomness in conjunction with the current global random seed
// in tendermint/libs/common to generate the private key.
func GenPrivKey() PrivKey {
return genPrivKey(crypto.CReader())
}
func genPrivKey(rng io.Reader) PrivKey {
msk, err := sr25519.GenerateMiniSecretKey(rng)
if err != nil {
panic("sr25519: failed to generate MiniSecretKey: " + err.Error())
}
sk := msk.ExpandEd25519()
return PrivKey{
msk: *msk,
kp: sk.KeyPair(),
}
}
// GenPrivKeyFromSecret hashes the secret with SHA2, and uses
// that 32 byte output to create the private key.
// NOTE: secret should be the output of a KDF like bcrypt,
// if it's derived from user input.
func GenPrivKeyFromSecret(secret []byte) PrivKey {
seed := crypto.Sha256(secret) // Not Ripemd160 because we want 32 bytes.
var privKey PrivKey
if err := privKey.msk.UnmarshalBinary(seed); err != nil {
panic("sr25519: failed to deserialize MiniSecretKey: " + err.Error())
}
sk := privKey.msk.ExpandEd25519()
privKey.kp = sk.KeyPair()
return privKey
}