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crypto, crypto/ecies, crypto/secp256k1: libsecp256k1 scalar mult

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thanks to Felix Lange (fjl) for help with design & impl
This commit is contained in:
Gustav Simonsson
2015-09-29 19:37:44 +02:00
parent 27a50c8f4b
commit c8ad64f33c
16 changed files with 321 additions and 171 deletions
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28
crypto/secp256k1/secp256.go
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@ -20,6 +20,7 @@ package secp256k1
/*
#cgo CFLAGS: -I./libsecp256k1
#cgo CFLAGS: -I./libsecp256k1/src/
#cgo darwin CFLAGS: -I/usr/local/include
#cgo freebsd CFLAGS: -I/usr/local/include
#cgo linux,arm CFLAGS: -I/usr/local/arm/include
@ -35,6 +36,7 @@ package secp256k1
#define NDEBUG
#include "./libsecp256k1/src/secp256k1.c"
#include "./libsecp256k1/src/modules/recovery/main_impl.h"
#include "pubkey_scalar_mul.h"
typedef void (*callbackFunc) (const char* msg, void* data);
extern void secp256k1GoPanicIllegal(const char* msg, void* data);
@ -44,6 +46,7 @@ import "C"
import (
"errors"
"math/big"
"unsafe"
"github.com/ethereum/go-ethereum/crypto/randentropy"
@ -56,13 +59,16 @@ import (
> store private keys in buffer and shuffle (deters persistance on swap disc)
> byte permutation (changing)
> xor with chaning random block (to deter scanning memory for 0x63) (stream cipher?)
> on disk: store keys in wallets
*/
// holds ptr to secp256k1_context_struct (see secp256k1/include/secp256k1.h)
var context *C.secp256k1_context
var (
context *C.secp256k1_context
N *big.Int
)
func init() {
N, _ = new(big.Int).SetString("fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141", 16)
// around 20 ms on a modern CPU.
context = C.secp256k1_context_create(3) // SECP256K1_START_SIGN | SECP256K1_START_VERIFY
C.secp256k1_context_set_illegal_callback(context, C.callbackFunc(C.secp256k1GoPanicIllegal), nil)
@ -78,7 +84,6 @@ var (
func GenerateKeyPair() ([]byte, []byte) {
var seckey []byte = randentropy.GetEntropyCSPRNG(32)
var seckey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&seckey[0]))
var pubkey64 []byte = make([]byte, 64) // secp256k1_pubkey
var pubkey65 []byte = make([]byte, 65) // 65 byte uncompressed pubkey
pubkey64_ptr := (*C.secp256k1_pubkey)(unsafe.Pointer(&pubkey64[0]))
@ -96,7 +101,7 @@ func GenerateKeyPair() ([]byte, []byte) {
var output_len C.size_t
_ = C.secp256k1_ec_pubkey_serialize( // always returns 1
C.secp256k1_ec_pubkey_serialize( // always returns 1
context,
pubkey65_ptr,
&output_len,
@ -163,7 +168,7 @@ func Sign(msg []byte, seckey []byte) ([]byte, error) {
sig_serialized_ptr := (*C.uchar)(unsafe.Pointer(&sig_serialized[0]))
var recid C.int
_ = C.secp256k1_ecdsa_recoverable_signature_serialize_compact(
C.secp256k1_ecdsa_recoverable_signature_serialize_compact(
context,
sig_serialized_ptr, // 64 byte compact signature
&recid,
@ -254,3 +259,16 @@ func checkSignature(sig []byte) error {
}
return nil
}
// reads num into buf as big-endian bytes.
func readBits(buf []byte, num *big.Int) {
const wordLen = int(unsafe.Sizeof(big.Word(0)))
i := len(buf)
for _, d := range num.Bits() {
for j := 0; j < wordLen && i > 0; j++ {
i--
buf[i] = byte(d)
d >>= 8
}
}
}