OpenSSL：EC_POINT_set_compressed_coordinates_GFp 段错误

Question

使用 gdb 尝试查明段错误（并没有真正帮助），但我可能传递了错误的参数。这是代码和回溯：

echd.cc

#include <node.h>
#include <nan.h>
#include <openssl/evp.h>
#include <openssl/ec.h>

using v8::Handle;
using v8::FunctionTemplate;
using v8::Object;
using v8::String;

static const size_t PRIVKEY_SIZE = 32;
static const size_t PUBKEY_SIZE = 65;
static const size_t COMPRESSED_PUBKEY_SIZE = 33;

#define CHECK(cond) do { if (!(cond)) goto error; } while (0)

int derive(const uint8_t* privkey_a, const uint8_t* pubkey_b, uint8_t* shared) {
  int rc = -1;
  int res;
  BIGNUM* pkey_bn = NULL;
  EC_KEY* pkey = NULL;
  bool compressed = false;
  EC_KEY* peerkey = NULL;
  int compressed_y_bit = 0;
  EC_POINT* peerkey_p = NULL;
  const EC_GROUP* peerkey_group = NULL;
  BN_CTX* peerkey_ctx = NULL;
  BIGNUM* peerkey_bn = NULL;
  BIGNUM* peerkey_bn_x = NULL;
  BIGNUM* peerkey_bn_y = NULL;
  EVP_PKEY* evp_pkey = NULL;
  EVP_PKEY* evp_peerkey = NULL;
  EVP_PKEY_CTX* ctx = NULL;
  size_t shared_len = PRIVKEY_SIZE;

  // Private key A.
  CHECK((pkey_bn = BN_bin2bn(privkey_a, PRIVKEY_SIZE, NULL)) != NULL);
  CHECK((pkey = EC_KEY_new_by_curve_name(NID_secp256k1)) != NULL);
  CHECK(EC_KEY_set_private_key(pkey, pkey_bn) == 1);
  CHECK((evp_pkey = EVP_PKEY_new()) != NULL);
  CHECK(EVP_PKEY_set1_EC_KEY(evp_pkey, pkey) == 1);

  // Public key B.
  CHECK((peerkey = EC_KEY_new_by_curve_name(NID_secp256k1)) != NULL);
  (pubkey_b[0] == 2 || pubkey_b[0] == 3) ? compressed = true : compressed = false;
  if (compressed) {
    (pubkey_b[0] == 2) ? compressed_y_bit = 0 : compressed_y_bit = 1;
    CHECK((peerkey_group = EC_KEY_get0_group(peerkey)) != NULL);
    CHECK((peerkey_ctx = BN_CTX_new()) != NULL);
    CHECK((peerkey_bn = BN_bin2bn(pubkey_b+1, COMPRESSED_PUBKEY_SIZE, NULL)) != NULL);
    CHECK((EC_POINT_set_compressed_coordinates_GFp(peerkey_group,
                                                 peerkey_p,
                                                 peerkey_bn,
                                                 compressed_y_bit,
                                                 NULL)) != NULL);
    ...

回溯

(gdb) bt
#0  0x00000000012097a3 in EC_POINT_set_compressed_coordinates_GFp ()
#1  0x00007ffff4648446 in derive (privkey_a=0x2214af0 '[=12=]4' <repeats 32 times>, " 2+[=12=]2", pubkey_b=0x2214ec0 "[=12=]3345V{2d@1]>ժ2[=12=]5e7604`H17475155\a72+[=12=]2", shared=0x222d5d0 " c,[=12=]2") at ../ecdh.cc:51
#2  0x00007ffff4648817 in Derive (info=...) at ../ecdh.cc:117
#3  0x00007ffff4647756 in Nan::imp::FunctionCallbackWrapper (info=...) at ../node_modules/nan/nan_callbacks_12_inl.h:176
#4  0x0000000000a94a43 in v8::internal::FunctionCallbackArguments::Call(void (*)(v8::FunctionCallbackInfo<v8::Value> const&)) ()
#5  0x0000000000b0bbec in v8::internal::MaybeHandle<v8::internal::Object> v8::internal::(anonymous namespace)::HandleApiCallHelper<false>(v8::internal::Isolate*, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::FunctionTemplateInfo>, v8::internal::Handle<v8::internal::Object>, v8::internal::BuiltinArguments) ()
#6  0x0000000000b0c83f in v8::internal::Builtin_HandleApiCall(int, v8::internal::Object**, v8::internal::Isolate*) ()
#7  0x00002b6f5fe042fd in ?? ()
#8  0x00002b6f5fe04241 in ?? ()
#9  0x00007fffffffc610 in ?? ()
#10 0x0000000000000006 in ?? ()
---Type <return> to continue, or q <return> to quit---q
Quit

Answer 1

您对 EC_POINT_set_compressed_coordinates_GFp() 的调用中的 peerkey_p 参数是 NULL，而它应该是已初始化的 EC_POINT *。在调用该函数之前添加类似这样的内容（为清楚起见省略检查）：

peerkey_p = EC_POINT_new(peerkey_group);

这将消除段错误。

您使用 COMPRESSED_PUBKEY_SIZE 等于 33 时似乎还有另一个错误。是的，public 键的总大小是 33 字节。但是在将指针 pubkey_b 前进 1 字节后，只有 32 字节与 BN_bin2bn() 函数相关。

此外，EC_POINT_set_compressed_coordinates_GFp()的return值是一个int，不是指针。因此，与其将其与 NULL 进行比较，不如将其与 1.

的成功值进行比较

OpenSSL：EC_POINT_set_compressed_coordinates_GFp 段错误

OpenSSL: EC_POINT_set_compressed_coordinates_GFp segfault

c++

node.js

openssl

node-gyp