well-goknown/vendor/github.com/nbd-wtf/go-nostr/signature_libsecp256k1.go

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2024-10-12 20:48:05 +00:00
//go:build libsecp256k1
package nostr
/*
#cgo LDFLAGS: -lsecp256k1
#include <secp256k1.h>
#include <secp256k1_schnorrsig.h>
#include <secp256k1_extrakeys.h>
*/
import "C"
import (
"crypto/rand"
"crypto/sha256"
"encoding/hex"
"errors"
"fmt"
"unsafe"
"github.com/btcsuite/btcd/btcec/v2/schnorr"
)
// CheckSignature checks if the signature is valid for the id
// (which is a hash of the serialized event content).
// returns an error if the signature itself is invalid.
func (evt Event) CheckSignature() (bool, error) {
var pk [32]byte
_, err := hex.Decode(pk[:], []byte(evt.PubKey))
if err != nil {
return false, fmt.Errorf("event pubkey '%s' is invalid hex: %w", evt.PubKey, err)
}
var sig [64]byte
_, err = hex.Decode(sig[:], []byte(evt.Sig))
if err != nil {
return false, fmt.Errorf("event signature '%s' is invalid hex: %w", evt.Sig, err)
}
msg := sha256.Sum256(evt.Serialize())
var xonly C.secp256k1_xonly_pubkey
if C.secp256k1_xonly_pubkey_parse(globalSecp256k1Context, &xonly, (*C.uchar)(unsafe.Pointer(&pk[0]))) != 1 {
return false, fmt.Errorf("failed to parse xonly pubkey")
}
res := C.secp256k1_schnorrsig_verify(globalSecp256k1Context, (*C.uchar)(unsafe.Pointer(&sig[0])), (*C.uchar)(unsafe.Pointer(&msg[0])), 32, &xonly)
return res == 1, nil
}
// Sign signs an event with a given privateKey.
func (evt *Event) Sign(secretKey string, signOpts ...schnorr.SignOption) error {
sk, err := hex.DecodeString(secretKey)
if err != nil {
return fmt.Errorf("Sign called with invalid secret key '%s': %w", secretKey, err)
}
if evt.Tags == nil {
evt.Tags = make(Tags, 0)
}
var keypair C.secp256k1_keypair
if C.secp256k1_keypair_create(globalSecp256k1Context, &keypair, (*C.uchar)(unsafe.Pointer(&sk[0]))) != 1 {
return errors.New("failed to parse private key")
}
var xonly C.secp256k1_xonly_pubkey
var pk [32]byte
C.secp256k1_keypair_xonly_pub(globalSecp256k1Context, &xonly, nil, &keypair)
C.secp256k1_xonly_pubkey_serialize(globalSecp256k1Context, (*C.uchar)(unsafe.Pointer(&pk[0])), &xonly)
evt.PubKey = hex.EncodeToString(pk[:])
h := sha256.Sum256(evt.Serialize())
var sig [64]byte
var random [32]byte
rand.Read(random[:])
if C.secp256k1_schnorrsig_sign32(globalSecp256k1Context, (*C.uchar)(unsafe.Pointer(&sig[0])), (*C.uchar)(unsafe.Pointer(&h[0])), &keypair, (*C.uchar)(unsafe.Pointer(&random[0]))) != 1 {
return errors.New("failed to sign message")
}
evt.ID = hex.EncodeToString(h[:])
evt.Sig = hex.EncodeToString(sig[:])
return nil
}
var globalSecp256k1Context *C.secp256k1_context
func init() {
globalSecp256k1Context = C.secp256k1_context_create(C.SECP256K1_CONTEXT_SIGN | C.SECP256K1_CONTEXT_VERIFY)
if globalSecp256k1Context == nil {
panic("failed to create secp256k1 context")
}
}