From 2e7fb078722decb07ab8da7fb59c8ec46fb32fd1 Mon Sep 17 00:00:00 2001
From: David Stainton <dstainton415@gmail.com>
Date: Mon, 17 Oct 2022 23:30:36 -0400
Subject: [PATCH] Add GenerateKeyPairWithRNG
---
binding.go | 57 +++++++++++++++++++++++++++++++++++++++++++++++--
binding_test.go | 11 ++++++++++
2 files changed, 66 insertions(+), 2 deletions(-)
diff --git a/binding.go b/binding.go
index 986174d..df19c0e 100644
--- a/binding.go
+++ b/binding.go
@@ -1,14 +1,31 @@
package ctidh
-// #include "binding.h"
-// #include <csidh.h>
+/*
+#include "binding.h"
+#include <csidh.h>
+
+void custom_gen_private(private_key *priv) {
+ csidh_private_withrng(priv, fillrandom_custom);
+}
+
+void fillrandom_custom(
+ void *const outptr,
+ const size_t outsz,
+ const uintptr_t context)
+{
+ (void) context;
+ go_fillrandom(outptr, outsz);
+}
+*/
import "C"
import (
"bytes"
"crypto/hmac"
"encoding/pem"
"fmt"
+ "io"
"io/ioutil"
+ "sync"
"unsafe"
)
@@ -33,6 +50,9 @@ var (
// ErrCTIDH indicates a group action failure.
ErrCTIDH error = fmt.Errorf("%s: group action failure", Name())
+
+ privateKeyRNGLock sync.Mutex
+ privateKeyRNG io.Reader = nil
)
// ErrPEMKeyTypeMismatch returns an error indicating that we tried
@@ -300,6 +320,39 @@ func GenerateKeyPair() (*PrivateKey, *PublicKey) {
return privKey, DerivePublicKey(privKey)
}
+//export go_fillrandom
+func go_fillrandom(outptr unsafe.Pointer, outsz C.size_t) {
+ buf := make([]byte, outsz)
+ privateKeyRNGLock.Lock()
+ rng := privateKeyRNG
+ privateKeyRNGLock.Unlock()
+ count, err := rng.Read(buf)
+ if err != nil {
+ panic(err)
+ }
+ if count != int(outsz) {
+ panic("rng fail")
+ }
+ p := uintptr(outptr)
+ for i := 0; i < int(outsz); i++ {
+ (*(*uint8)(unsafe.Pointer(p))) = uint8(buf[i])
+ p += 1
+ }
+}
+
+// GenerateKeyPairWithRNG uses the given RNG to derive a new keypair.
+// HOWEVER, if GenerateKeyPairWithRNG is called by multiple threads
+// then the rng is overwritten with each call which can unintentionally
+// cause multiple RNGs to be used to generate the keypair.
+func GenerateKeyPairWithRNG(rng io.Reader) (*PrivateKey, *PublicKey) {
+ privKey := new(PrivateKey)
+ privateKeyRNGLock.Lock()
+ privateKeyRNG = rng
+ privateKeyRNGLock.Unlock()
+ C.custom_gen_private(&privKey.privateKey)
+ return privKey, DerivePublicKey(privKey)
+}
+
func groupAction(privateKey *PrivateKey, publicKey *PublicKey) *PublicKey {
sharedKey := new(PublicKey)
ok := C.csidh(&sharedKey.publicKey, &publicKey.publicKey, &privateKey.privateKey)
diff --git a/binding_test.go b/binding_test.go
index e18bba6..2efbfac 100644
--- a/binding_test.go
+++ b/binding_test.go
@@ -1,6 +1,7 @@
package ctidh
import (
+ "crypto/rand"
"os"
"path/filepath"
"testing"
@@ -8,6 +9,16 @@ import (
"github.com/stretchr/testify/require"
)
+func TestGenerateKeyPairWithRNG(t *testing.T) {
+ privateKey, publicKey := GenerateKeyPairWithRNG(rand.Reader)
+
+ zeros := make([]byte, PublicKeySize)
+ require.NotEqual(t, privateKey.Bytes(), zeros)
+ require.NotEqual(t, publicKey.Bytes(), zeros)
+
+ t.Logf("privateKey.Bytes() %x", privateKey.Bytes())
+}
+
func TestPrivateKeyPEMSerialization(t *testing.T) {
privateKey, _ := GenerateKeyPair()
--
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