如何用C++中的OpenSSL从DER文件中读取椭圆曲线公钥

BIO* bio = BIO_new_file("public_key.der", "rb");
if (bio == nullptr) {
    // 处理文件打开失败的情况
}

EVP_PKEY* evpKey = d2i_PUBKEY_bio(bio, nullptr);
if (evpKey == nullptr) {
    // 处理公钥读取失败的情况
}

int keyType = EVP_PKEY_base_id(evpKey);
int keyLength = EVP_PKEY_bits(evpKey);

// 使用公钥进行加密
unsigned char* plaintext = (unsigned char*)"Hello, World!";
int plaintextLength = strlen((const char*)plaintext);
unsigned char* ciphertext = new unsigned char[EVP_PKEY_size(evpKey)];
int ciphertextLength = EVP_PKEY_encrypt_old(ciphertext, plaintext, plaintextLength, evpKey);

// 使用公钥进行验证
unsigned char* signature = ...; // 待验证的签名数据
int signatureLength = ...; // 签名数据的长度
int verifyResult = EVP_PKEY_verify(evpKey, signature, signatureLength, plaintext, plaintextLength);