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306 lines
8.1 KiB
306 lines
8.1 KiB
package secp256k1
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/*
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#cgo CFLAGS: -std=gnu99 -Wno-error
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#cgo darwin CFLAGS: -I/usr/local/include
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#cgo LDFLAGS: -lgmp
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#cgo darwin LDFLAGS: -L/usr/local/lib
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#define USE_FIELD_10X26
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#define USE_NUM_GMP
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#define USE_FIELD_INV_BUILTIN
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#include "./secp256k1/src/secp256k1.c"
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*/
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import "C"
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import (
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"bytes"
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"errors"
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"unsafe"
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"github.com/ethereum/go-ethereum/crypto/randentropy"
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)
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//#define USE_FIELD_5X64
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/*
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Todo:
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> Centralize key management in module
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> add pubkey/private key struct
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> Dont let keys leave module; address keys as ints
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> store private keys in buffer and shuffle (deters persistance on swap disc)
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> Byte permutation (changing)
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> xor with chaning random block (to deter scanning memory for 0x63) (stream cipher?)
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On Disk
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> Store keys in wallets
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> use slow key derivation function for wallet encryption key (2 seconds)
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*/
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func init() {
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C.secp256k1_start() //takes 10ms to 100ms
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}
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func Stop() {
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C.secp256k1_stop()
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}
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/*
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int secp256k1_ecdsa_pubkey_create(
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unsigned char *pubkey, int *pubkeylen,
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const unsigned char *seckey, int compressed);
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*/
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/** Compute the public key for a secret key.
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* In: compressed: whether the computed public key should be compressed
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* seckey: pointer to a 32-byte private key.
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* Out: pubkey: pointer to a 33-byte (if compressed) or 65-byte (if uncompressed)
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* area to store the public key.
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* pubkeylen: pointer to int that will be updated to contains the pubkey's
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* length.
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* Returns: 1: secret was valid, public key stores
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* 0: secret was invalid, try again.
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*/
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//pubkey, seckey
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func GenerateKeyPair() ([]byte, []byte) {
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pubkey_len := C.int(65)
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const seckey_len = 32
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var pubkey []byte = make([]byte, pubkey_len)
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var seckey []byte = randentropy.GetEntropyMixed(seckey_len)
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var pubkey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&pubkey[0]))
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var seckey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&seckey[0]))
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ret := C.secp256k1_ecdsa_pubkey_create(
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pubkey_ptr, &pubkey_len,
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seckey_ptr, 0)
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if ret != C.int(1) {
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return GenerateKeyPair() //invalid secret, try again
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}
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return pubkey, seckey
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}
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func GeneratePubKey(seckey []byte) ([]byte, error) {
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if err := VerifySeckeyValidity(seckey); err != nil {
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return nil, err
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}
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pubkey_len := C.int(65)
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const seckey_len = 32
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var pubkey []byte = make([]byte, pubkey_len)
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var pubkey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&pubkey[0]))
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var seckey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&seckey[0]))
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ret := C.secp256k1_ecdsa_pubkey_create(
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pubkey_ptr, &pubkey_len,
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seckey_ptr, 0)
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if ret != C.int(1) {
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return nil, errors.New("Unable to generate pubkey from seckey")
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}
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return pubkey, nil
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}
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/*
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* Create a compact ECDSA signature (64 byte + recovery id).
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* Returns: 1: signature created
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* 0: nonce invalid, try another one
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* In: msg: the message being signed
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* msglen: the length of the message being signed
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* seckey: pointer to a 32-byte secret key (assumed to be valid)
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* nonce: pointer to a 32-byte nonce (generated with a cryptographic PRNG)
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* Out: sig: pointer to a 64-byte array where the signature will be placed.
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* recid: pointer to an int, which will be updated to contain the recovery id.
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*/
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/*
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int secp256k1_ecdsa_sign_compact(const unsigned char *msg, int msglen,
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unsigned char *sig64,
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const unsigned char *seckey,
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const unsigned char *nonce,
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int *recid);
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*/
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func Sign(msg []byte, seckey []byte) ([]byte, error) {
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nonce := randentropy.GetEntropyMixed(32)
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var sig []byte = make([]byte, 65)
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var recid C.int
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var msg_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&msg[0]))
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var seckey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&seckey[0]))
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var nonce_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&nonce[0]))
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var sig_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&sig[0]))
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if C.secp256k1_ecdsa_seckey_verify(seckey_ptr) != C.int(1) {
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return nil, errors.New("Invalid secret key")
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}
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ret := C.secp256k1_ecdsa_sign_compact(
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msg_ptr, C.int(len(msg)),
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sig_ptr,
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seckey_ptr,
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nonce_ptr,
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&recid)
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sig[64] = byte(int(recid))
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if ret != C.int(1) {
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// nonce invalid, retry
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return Sign(msg, seckey)
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}
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return sig, nil
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}
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/*
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* Verify an ECDSA secret key.
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* Returns: 1: secret key is valid
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* 0: secret key is invalid
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* In: seckey: pointer to a 32-byte secret key
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*/
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func VerifySeckeyValidity(seckey []byte) error {
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if len(seckey) != 32 {
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return errors.New("priv key is not 32 bytes")
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}
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var seckey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&seckey[0]))
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ret := C.secp256k1_ecdsa_seckey_verify(seckey_ptr)
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if int(ret) != 1 {
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return errors.New("invalid seckey")
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}
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return nil
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}
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/*
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* Validate a public key.
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* Returns: 1: valid public key
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* 0: invalid public key
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*/
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func VerifyPubkeyValidity(pubkey []byte) error {
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if len(pubkey) != 65 {
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return errors.New("pub key is not 65 bytes")
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}
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var pubkey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&pubkey[0]))
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ret := C.secp256k1_ecdsa_pubkey_verify(pubkey_ptr, 65)
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if int(ret) != 1 {
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return errors.New("invalid pubkey")
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}
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return nil
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}
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func VerifySignatureValidity(sig []byte) bool {
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//64+1
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if len(sig) != 65 {
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return false
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}
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//malleability check, highest bit must be 1
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if (sig[32] & 0x80) == 0x80 {
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return false
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}
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//recovery id check
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if sig[64] >= 4 {
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return false
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}
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return true
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}
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//for compressed signatures, does not need pubkey
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func VerifySignature(msg []byte, sig []byte, pubkey1 []byte) error {
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if msg == nil || sig == nil || pubkey1 == nil {
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return errors.New("inputs must be non-nil")
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}
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if len(sig) != 65 {
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return errors.New("invalid signature length")
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}
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if len(pubkey1) != 65 {
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return errors.New("Invalid public key length")
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}
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//to enforce malleability, highest bit of S must be 0
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//S starts at 32nd byte
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if (sig[32] & 0x80) == 0x80 { //highest bit must be 1
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return errors.New("Signature not malleable")
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}
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if sig[64] >= 4 {
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return errors.New("Recover byte invalid")
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}
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// if pubkey recovered, signature valid
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pubkey2, err := RecoverPubkey(msg, sig)
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if err != nil {
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return err
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}
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if len(pubkey2) != 65 {
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return errors.New("Invalid recovered public key length")
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}
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if !bytes.Equal(pubkey1, pubkey2) {
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return errors.New("Public key does not match recovered public key")
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}
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return nil
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}
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/*
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int secp256k1_ecdsa_recover_compact(const unsigned char *msg, int msglen,
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const unsigned char *sig64,
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unsigned char *pubkey, int *pubkeylen,
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int compressed, int recid);
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*/
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/*
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* Recover an ECDSA public key from a compact signature.
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* Returns: 1: public key succesfully recovered (which guarantees a correct signature).
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* 0: otherwise.
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* In: msg: the message assumed to be signed
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* msglen: the length of the message
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* compressed: whether to recover a compressed or uncompressed pubkey
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* recid: the recovery id (as returned by ecdsa_sign_compact)
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* Out: pubkey: pointer to a 33 or 65 byte array to put the pubkey.
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* pubkeylen: pointer to an int that will contain the pubkey length.
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*/
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//recovers the public key from the signature
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//recovery of pubkey means correct signature
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func RecoverPubkey(msg []byte, sig []byte) ([]byte, error) {
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if len(sig) != 65 {
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return nil, errors.New("Invalid signature length")
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}
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var pubkey []byte = make([]byte, 65)
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var msg_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&msg[0]))
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var sig_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&sig[0]))
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var pubkey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&pubkey[0]))
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var pubkeylen C.int
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ret := C.secp256k1_ecdsa_recover_compact(
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msg_ptr, C.int(len(msg)),
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sig_ptr,
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pubkey_ptr, &pubkeylen,
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C.int(0), C.int(sig[64]),
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)
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if ret == C.int(0) {
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return nil, errors.New("Failed to recover public key")
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} else if pubkeylen != C.int(65) {
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return nil, errors.New("Impossible Error: Invalid recovered public key length")
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} else {
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return pubkey, nil
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}
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return nil, errors.New("Impossible Error: func RecoverPubkey has reached an unreachable state")
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}
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