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package crypto
import (
"fmt"
secp256k1 "github.com/btcsuite/btcd/btcec"
ledger "github.com/zondax/ledger-goclient"
)
func pubkeyLedgerSecp256k1(device *ledger.Ledger, path DerivationPath) (pub PubKey, err error) {
key, err := device.GetPublicKeySECP256K1(path)
if err != nil {
return nil, fmt.Errorf("error fetching public key: %v", err)
}
var p PubKeySecp256k1
// Reserialize in the 33-byte compressed format
cmp, err := secp256k1.ParsePubKey(key[:], secp256k1.S256())
copy(p[:], cmp.SerializeCompressed())
pub = p
return
}
func signLedgerSecp256k1(device *ledger.Ledger, path DerivationPath, msg []byte) (sig Signature, err error) {
bsig, err := device.SignSECP256K1(path, msg)
if err != nil {
return sig, err
}
sig = SignatureSecp256k1FromBytes(bsig)
return
}
// PrivKeyLedgerSecp256k1 implements PrivKey, calling the ledger nano
// we cache the PubKey from the first call to use it later
type PrivKeyLedgerSecp256k1 struct {
// PubKey should be private, but we want to encode it via go-amino
// so we can view the address later, even without having the ledger
// attached
CachedPubKey PubKey
Path DerivationPath
}
// NewPrivKeyLedgerSecp256k1 will generate a new key and store the
// public key for later use.
func NewPrivKeyLedgerSecp256k1(path DerivationPath) (PrivKey, error) {
var pk PrivKeyLedgerSecp256k1
pk.Path = path
// getPubKey will cache the pubkey for later use,
// this allows us to return an error early if the ledger
// is not plugged in
_, err := pk.getPubKey()
return &pk, err
}
// ValidateKey allows us to verify the sanity of a key
// after loading it from disk
func (pk PrivKeyLedgerSecp256k1) ValidateKey() error {
// getPubKey will return an error if the ledger is not
// properly set up...
pub, err := pk.forceGetPubKey()
if err != nil {
return err
}
// verify this matches cached address
if !pub.Equals(pk.CachedPubKey) {
return fmt.Errorf("cached key does not match retrieved key")
}
return nil
}
// AssertIsPrivKeyInner fulfils PrivKey Interface
func (pk *PrivKeyLedgerSecp256k1) AssertIsPrivKeyInner() {}
// Bytes fulfils PrivKey Interface - but it stores the cached pubkey so we can verify
// the same key when we reconnect to a ledger
func (pk PrivKeyLedgerSecp256k1) Bytes() []byte {
return cdc.MustMarshalBinaryBare(pk)
}
// Sign calls the ledger and stores the PubKey for future use
//
// Communication is checked on NewPrivKeyLedger and PrivKeyFromBytes,
// returning an error, so this should only trigger if the privkey is held
// in memory for a while before use.
func (pk PrivKeyLedgerSecp256k1) Sign(msg []byte) (Signature, error) {
dev, err := getLedger()
if err != nil {
return nil, err
}
sig, err := signLedgerSecp256k1(dev, pk.Path, msg)
if err != nil {
return nil, err
}
pub, err := pubkeyLedgerSecp256k1(dev, pk.Path)
if err != nil {
return nil, err
}
// if we have no pubkey yet, store it for future queries
if pk.CachedPubKey == nil {
pk.CachedPubKey = pub
} else if !pk.CachedPubKey.Equals(pub) {
return nil, fmt.Errorf("stored key does not match signing key")
}
return sig, nil
}
// PubKey returns the stored PubKey
func (pk PrivKeyLedgerSecp256k1) PubKey() (PubKey, error) {
return pk.getPubKey()
}
// getPubKey reads the pubkey from cache or from the ledger itself
// since this involves IO, it may return an error, which is not exposed
// in the PubKey interface, so this function allows better error handling
func (pk PrivKeyLedgerSecp256k1) getPubKey() (key PubKey, err error) {
// if we have no pubkey, set it
if pk.CachedPubKey == nil {
pk.CachedPubKey, err = pk.forceGetPubKey()
}
return pk.CachedPubKey, err
}
// forceGetPubKey is like getPubKey but ignores any cached key
// and ensures we get it from the ledger itself.
func (pk PrivKeyLedgerSecp256k1) forceGetPubKey() (key PubKey, err error) {
dev, err := getLedger()
if err != nil {
return key, fmt.Errorf("cannot connect to Ledger device - error: %v", err)
}
key, err = pubkeyLedgerSecp256k1(dev, pk.Path)
if err != nil {
return key, fmt.Errorf("please open Cosmos app on the Ledger device - error: %v", err)
}
return key, err
}
// Equals fulfils PrivKey Interface - makes sure both keys refer to the
// same
func (pk PrivKeyLedgerSecp256k1) Equals(other PrivKey) bool {
if ledger, ok := other.(*PrivKeyLedgerSecp256k1); ok {
return pk.CachedPubKey.Equals(ledger.CachedPubKey)
}
return false
}